INTRODUCTION — Chronic opioid therapy, defined as daily use of medically-prescribed opioids for at least 90 days, has increased substantially in developed countries since 1980 [1,2]. In the United States, in 2019 it was estimated that approximately 4.5 percent of patients were receiving opioids for chronic pain [3].
Patients receiving chronic opioid therapy for pain commonly experience episodes of acute pain, sometimes due to new injuries or illnesses and sometimes related to the cause of their chronic pain, eg, postoperatively following knee replacement for advanced osteoarthritis.
This topic presents a stepwise approach to patients receiving chronic opioids who experience acute pain, including postoperative pain. Management of acute pain in patients with treated and untreated opioid use disorder, and management of patients with cancer-related pain (including breakthrough pain) are discussed separately.
●(See "Medication for opioid use disorder".)
●(See "Management of acute pain in adults with opioid use disorder".)
Management of acute pain in patients with sickle cell disease, many of whom take opioids chronically, is also discussed separately. (See "Acute vaso-occlusive pain management in sickle cell disease".)
The overarching principles of acute pain management are discussed separately. (See "Management of acute perioperative pain in adults".)
TREATMENT GOALS — In patients chronically using opioids, goals include providing adequate analgesia, preventing withdrawal and abstinence syndrome, and avoiding development or relapse of OUD. The imperatives to adequately treat pain but to avoid iatrogenic opioid use disorder and opioid overdose make medical decisions particularly complex. Patients receiving opioid therapy for pain even in the absence of OUD are at risk for opioid dose escalation during each episode of pain, and also at risk for remaining on higher doses of opioids even when an episode of pain subsides.
The guiding principles for acute pain management in these patients are similar to those that apply to patients who do not use opioids chronically. They are shown in a table (table 1) and are discussed separately. (See "Management of acute perioperative pain in adults" and 'Creating a plan for treatment' below.) A basic principle of acute pain management for all patients should be to employ multimodal analgesia including nonpharmacologic methods to minimize or eliminate the use of opioids whenever possible. Opioids should be avoided because of their side effects (ie, nausea, vomiting, slowed bowel recovery, sedation, urinary retention and, especially, respiratory depression), and also because of the contribution of prescription opioids to the ongoing opioid epidemic [4-7].
CHALLENGES — There are both psychosocial and biological reasons why treating acute pain in patients on long-term opioids can be difficult.
Psychosocial factors — Evaluation and treatment of acute pain in patients who take opioids often occurs in an atmosphere of mutual distrust and, for patients, stigmatization and inadequate access to pain control. It can be difficult to decide upon the cause of acute pain in some patients who are on long-term opioid therapy, eg, whether the episode represents a flare-up of the pre-existing problem or a new diagnosis.
●Clinicians may have concerns about malingering or opioid use disorder (OUD) that make it difficult to interpret or trust the patient-reported history [8].
●Many clinicians are not adequately trained to recognize and manage OUD. Based upon their clinical intuition, they may assume that a patient who uses opioids chronically has OUD. However, clinical assessment of the likelihood of misuse of prescribed opioids is often inaccurate and racially biased [9].
●Patients with a high requirement for opioids may be labeled as "drug seekers" or "addicts," and clinicians, out of appropriate concerns about overdose and addiction, may undertreat such patients' pain.
It is therefore critical that clinicians use objective methods to determine which patients are likely to have OUD and, when possible, make a specific diagnosis for the cause of pain. (See 'Assessment for opioid use disorder' below and "Management of acute pain in adults with opioid use disorder", section on 'Screening for OUD'.)
Biological factors — In daily practice it may be unclear whether acute pain represents exacerbation of a chronic condition or a new process. In addition, patients may have altered pain perception or pain-related behavior, further complicating the diagnosis of acute pain. Central sensitization, tolerance, and opioid-induced hyperalgesia (OIH) may contribute to difficulty managing pain in patients on chronic opioids.
Central sensitization is caused by amplified synaptic transfer of nociceptive impulses from the nociceptor terminal to dorsal horn neurons; the glutamate-activated N-methyl-D-aspartate (NMDA) receptor is integral to sensitization (see "Overview of chronic widespread (centralized) pain in the rheumatic diseases", section on 'Neurophysiologic and neuroimaging changes in chronic widespread pain'). Central sensitization is implicated both in opioid tolerance (ie, the requirement for increasing doses of opioids over time to maintain the same level of analgesia) as well as OIH, in which patients with chronic opioid exposure become more likely to experience pain with less intense noxious stimuli.
Animal and human studies have clearly established the existence of OIH but the relevance of such studies to everyday acute pain management is not clear. (See "Prevention and management of side effects in patients receiving opioids for chronic pain", section on 'Opioid-induced hyperalgesia'.)
EVALUATION — A careful history, physical examination, and appropriate diagnostic studies should be performed to attempt to determine the cause of acute pain.
Differential diagnosis of acute pain — A differential diagnosis taking into account the site and nature of pain should be developed. Acute pain may result from exacerbation of a chronically painful condition (eg, sickle cell crisis or arthritis flare), acute pain with an identifiable cause (eg, surgery, trauma), or an acutely painful medical condition (eg, diverticulitis, nephrolithiasis), cancer-related pain exacerbation (hemorrhage into a tumor, pathologic fracture, epidural metastasis with spinal cord compression, or obstruction/perforation of a hollow viscus), or in some cases, without an identifiable cause. Patients with opioid use disorder (OUD) are at risk of infectious causes of pain, including HIV-related infection, abscess, osteomyelitis, endocarditis, and septic arthritis. Psychosocial issues and spiritual distress can also evoke complaints of acute pain.
●Assessment of baseline pain intensity – The clinician should explore the patient's preexisting chronic pain and how the acute pain compares with the chronic pain in location, intensity, pattern, exacerbating and relieving factors, and quality. The patient should be asked about baseline chronic pain intensity at rest and during activity on an average day, using a numeric scale (figure 1).
●Exacerbation of chronic pain – A waxing and waning course is typical of many chronically painful conditions such as ulcerative colitis, rheumatic conditions (eg, rheumatoid arthritis, osteoarthritis), phantom limb pain, complex regional pain syndrome, sickle cell disease, fibromyalgia, and functional abdominal pain. It is common for patients to experience intermittent, unpredictable, and inexplicable flare-ups of their preexisting pain. Nonetheless, a specific cause for exacerbation should always be sought. As examples, exacerbations can be caused by medication interactions that decrease the effectiveness of an existing regimen, or the development of tolerance to the current analgesic regimen. Injury or localized infection of a chronically painful body part, diffuse inflammation as a result of infectious illness, or other physical stressors can exacerbate pain. Acute exacerbation of chronic pain is discussed in multiple other topics on specific disorders that cause chronic pain.
●Psychosocial causes for acute pain – Psychological stressors, including abuse, violence in the home, financial issues, family discord, or work-related stress can all lead to worsening chronic pain or new acute pain, particularly unexplained abdominal and pelvic pain [10]. We screen for trauma, domestic violence, sexual assault/abuse, and psychiatric disorders for patients on chronic opioid therapy who present with acute pain including an exacerbation of chronic pain. Depression, anxiety, and posttraumatic stress disorder (PTSD) are more common in patients with chronic pain than in the general population, and a worsening of psychiatric disorders may exacerbate patients' experience of pain [11,12]. Unprecedentedly high levels of anxiety and depression among the general population were observed during the COVID-19 pandemic [13]. These issues may themselves cause painful symptoms and sequelae. (See "COVID-19: Evaluation and management of adults with persistent symptoms following acute illness ("Long COVID")".)
Specific somatization disorders, such as conversion disorder or somatoform disorder can present as acute pain superimposed on chronic pain. Coordination with an outpatient provider who knows the patient well can help avoid unnecessary testing and medication trials in patients who suffer from these disorders. Though there are few data on the role of psychiatric disorders in acute pain, treatment of comorbid psychiatric disorders has been found to improve chronic pain [14]. (See "Somatic symptom disorder: Epidemiology and clinical presentation" and "Conversion disorder in adults: Terminology, diagnosis, and differential diagnosis".)
Baseline opioid dose — For patients who take opioids for chronic pain, the quantity of opioids used daily prior to the acute event should be ascertained as accurately as possible, including individual doses, intervals, and total daily dose. The patient-reported history should be confirmed using the prescription drug monitoring program (PDMP) or, if necessary, by contacting the dispensing pharmacy.
Assessment for opioid use disorder — As OUD becomes increasingly prevalent, it is important to distinguish between acute pain and drug seeking related to OUD. Patients with OUD who request opioids for acute pain present a diagnostic dilemma but should not be dismissed out of hand; they may have acute pain that requires adequate analgesia (see "Management of acute pain in adults with opioid use disorder", section on 'Patients receiving pharmacotherapy for opioid use disorder' and "Management of acute pain in adults with opioid use disorder", section on 'Patients with untreated opioid use disorder'). In addition, because OUD is a life-threatening illness that responds to treatment, it is incumbent on medical providers to make this alternative diagnosis and initiate treatment when possible [15,16].
CREATING A PLAN FOR TREATMENT — The plan for treatment of acute pain in all patients should be firmly based on the consideration of all relevant options that are judged by their potential benefits and risks. Treatment should start with nonopioid strategies, with opioids added only when anticipated or proven to be necessary, and the anticipated benefits outweigh potential risks [17]. The pain management strategy should be multimodal and include nonpharmacologic methods of pain control (ie, ice or heat, elevation, immobilization, rest, physical therapy, acupuncture, hypnosis, relaxation techniques, meditation, and other options), nonopioid analgesics, and regional anesthetic techniques as feasible. Opioids should be prescribed only when necessary and should be tapered and discontinued as quickly as possible.
The plan for pain control should be based on the degree of existing or expected pain (eg, after elective surgery). However, the plan must be flexible because pain intensity and the requirement for additional opioids may be unpredictable in patients who chronically use opioids, and often increases with activity. Practitioners should be prepared to titrate opioid doses upwards rapidly if pain relief is not achieved despite use of a multimodal regimen selected to correspond to the likely pain severity, and to taper opioids and other medications as pain intensity and opioid requirement subside.
In the patient who chronically uses opioids, it is helpful to discuss the plan with the patient and agree that acute opioid therapy (if warranted) should be temporary, with the goal to return to baseline opioid doses within the expected time for resolution or healing. If the expected outcome is not met, the acute pain should be reevaluated, particularly before increasing or extending opioid prescribing.
Preoperative opioid taper — Despite increasing calls to routinely taper or discontinue opioids prior to surgery, it is not clear that tapering itself improves outcomes after surgery. Multiple observational studies have found an association between preoperative chronic opioid use and worse outcomes after orthopedic surgery [18-22]. However, literature comparing patients who do wean opioids preoperatively with those who do not is scant, and there are no randomized trials. A single center retrospective cohort study of 120 patients who underwent knee or hip arthroplasty found that patients who weaned their chronic opioids preoperatively had improved postoperative outcomes compared with patients who did not wean [23]. In contrast, in an insurance claim database study of over 57,000 patients who chronically used opioids and underwent various common surgical procedures, preoperative changes in opioid doses were not associated with clinically significant differences in long term opioid utilization [24]. In retrospective studies like these, it is not clear whether patients' ability and willingness to wean opioids were surrogate markers for other factors that may affect outcome (eg, positive attitude, adherence to postoperative instructions, less severe pain, patient education in behavioral pain relief methods, an enthusiastic transitional pain service, or having unscheduled emergency operations).
All patients who chronically use opioids should have pain management optimized with nonopioid strategies, and in collaboration with the patient, opioids should be weaned or eliminated if benefits do not exceed risks (see "Approach to the management of chronic non-cancer pain in adults" and "Opioid tapering for patients with chronic pain"). Further study is required before recommending the routine practice of weaning opioids preoperatively with the primary purpose of improving surgical outcomes.
Continue the patient's baseline opioid regimen — The patient's baseline opioid regimen should be continued in order to prevent withdrawal and to maintain the existing level of chronic pain control, but should not be expected to be sufficient to treat the acute pain. If the patient is unable to take the baseline opioid in the usual formulation (eg, unable to take oral medication), the equivalent dose of an intravenous (IV) preparation should be administered. (See 'Parenteral opioids' below.)
Continuation of chronic opioids should be considered carefully and may not be appropriate for patients who are hemodynamically unstable due to comorbidities (eg, cardiac disease, sepsis) or trauma (eg, gunshot wounds, multitrauma). (See "Perioperative uses of intravenous opioids in adults: General considerations" and "Perioperative uses of intravenous opioids in adults: General considerations", section on 'Prevention and management of adverse opioid effects'.)
Patients commonly consume less than the full dose of opioids prescribed chronically, and instead hoard or divert pills. Therefore, patients should be monitored for respiratory depression when baseline doses as prescribed are administered in the hospital. If there is a specific concern for medication saving or diversion, or if the daily prescribed dose is particularly high (eg >100 morphine milligram equivalents [MME]), providers can consider giving a half-dose, monitoring for respiratory depression for one to three hours and providing the second half of the patient's dose if the first was well tolerated.
Potentially mild pain, anticipated duration one to two days — Mild pain can be expected after sprains, nonspecific low back pain, dental extraction, limited sunburn, or headaches. Nonopioid analgesics (eg, acetaminophen and nonsteroidal antiinflammatory drugs [NSAIDs]), including those administered topically, usually provide adequate analgesia; additional opioids, beyond the patient's baseline opioids, should not be required to adequately treat minor pain [25]. (See 'Nonopioid strategies for pain control' below.)
Potentially moderate pain, anticipated duration three to five days — Most laparoscopic and minimally invasive surgery, most soft tissue surgeries, limited second-degree burns, and noncompound and noncomminuted fractures are expected to result in moderate pain that lasts for several days. Moderate pain usually requires short-acting opioids, in addition to the patient's baseline opioid and nonopioid multimodal pain control strategies.
Because patients on chronic opioid therapy may have hyperalgesia, it can be difficult to predict accurately how severe and how prolonged their experience of pain will be and how much opioid will be required. Treatment of moderate pain in patients who chronically take opioids must be individualized. Patients on chronic opioids may require hospitalization for parenteral opioids or regional anesthesia for injuries and surgeries that could be managed on an outpatient basis in other populations.
In the emergency department, postoperative, or urgent care setting, it may be appropriate to trial a test dose of both nonopioid and oral opioid pain medication prior to discharge. If pain control is inadequate, we either admit the patient to the hospital for pain control or titrate oral opioids. (See 'Oral opioids' below.)
Factors that should prompt consideration of admission for pain control include:
●Inability to control the patient's pain with a test dose of nonopioid and oral opioid pharmacotherapy.
●Patient repeatedly presenting to the emergency department or clinic for inadequate pain control.
●Significant fear or concern on the part of the patient that pain will not be adequately controlled in the outpatient setting.
●Past history of difficulty with outpatient pain control in similar situations. (See 'Oral opioids' below and "Prescription of opioids for acute pain in opioid naïve patients", section on 'Moderate pain'.)
Potentially severe pain, anticipated duration five to seven days — Severe pain can be expected after major nonlaparoscopic abdominal or thoracic surgery, maxillofacial surgery, total knee replacement, compound fractures, and long bone fracture prior to definitive stabilization. Severe pain can sometimes be managed primarily with regional anesthesia techniques (eg, epidural analgesia, continuous plexus or peripheral nerve blocks) in addition to multimodal nonopioid analgesics, with reduced need for additional opioids beyond baseline while the regional block is in effect. (See "Management of acute perioperative pain in adults", section on 'Regional analgesia'.)
Patients who are opioid tolerant may require more extensive or denser regional block than opioid naïve patients. (See "Anesthesia for total knee arthroplasty", section on 'Choice of peripheral nerve block'.)
For patients in whom regional anesthesia is contraindicated or not feasible, treatment of severe pain usually requires parenteral opioids in the hospital until pain subsides to the point at which oral opioids can be prescribed. (See 'Parenteral opioids' below.)
OPTIONS FOR PAIN MANAGEMENT
Nonopioid strategies for pain control — Nonopioid (including nonpharmacologic) strategies are often sufficient for treating mild or moderate acute pain and can prevent overuse of opioids (table 2). If nonopioid strategies are effective but not fully adequate, they should be continued while opioids are initiated, thereby reducing the total opioid requirement for pain control.
The use of nonopioid analgesics and regional anesthesia techniques for pain are discussed in detail in multiple other topic reviews, including those that discuss specific painful disorders.
●(See "Management of acute perioperative pain in adults", section on 'Therapeutic options'.)
●(See "Nonopioid pharmacotherapy for acute pain in adults".)
●(See "Cancer pain management: Role of adjuvant analgesics (coanalgesics)".)
●Nonsteroidal antiinflammatory drugs (NSAIDS) – Both oral and intravenous (IV) formulations are available. (See "Nonopioid pharmacotherapy for acute pain in adults", section on 'Nonsteroidal anti-inflammatory drugs'.)
NSAIDs increase the risk of cardiac events, even when used for a short duration, and can cause gastritis, bleeding gastric ulcer, or renal impairment, so should be used with caution in patients at risk for these disorders. Nonselective NSAID-induced failure of surgical anastomoses [26] and potentially, risk of acute pain chronification have been described [27]. (See "Nonselective NSAIDs: Overview of adverse effects" and "NSAIDs: Adverse cardiovascular effects" and "Nonopioid pharmacotherapy for acute pain in adults", section on 'Nonsteroidal anti-inflammatory drugs'.)
●Acetaminophen – Both oral and IV formulations are available. Doses are shown in a table (table 2). Even at maximum doses, the intrinsic analgesic strength and opioid sparing of acetaminophen are weaker than most NSAIDs. Acetaminophen is contraindicated in patients with severe hepatic insufficiency or severe progressive liver disease. (See "Nonopioid pharmacotherapy for acute pain in adults", section on 'Acetaminophen'.)
Some oral opioid formulations and many over-the-counter pain and cold medications include acetaminophen. Patients are often unaware of the amount or even presence of acetaminophen in their medications; all of the patient's medications should be reviewed before prescribing additional acetaminophen.
●Ketamine – Low-dose IV ketamine can be used to manage acute pain and has been found to be effective in emergency department settings [28]. It is well-tolerated hemodynamically and has little effect upon respiratory drive, making it a useful agent in trauma patients. Some small studies suggest that the administration of perioperative ketamine may reduce long-term postoperative opioid use in patients who are on chronic opioids [29,30]. (See "Nonopioid pharmacotherapy for acute pain in adults", section on 'Ketamine'.)
●Lidocaine – IV intraoperative and postoperative lidocaine infusion can be used as part of multimodal pain management strategies, though the literature on the beneficial effects of lidocaine for pain management is inconclusive and the potential for toxicity is significant. The optimal dose and duration of therapy have not been defined. (See "Nonopioid pharmacotherapy for acute pain in adults", section on 'Intravenous lidocaine'.)
●Glucocorticoids – The use of systemic glucocorticoids for pain management should be individualized. Glucocorticoids are not usually first-line agents for acute non-cancer pain because of side effects (eg, impaired wound healing, infection, hyperglycemia, immunocompromise, hypertension), though these medications may be used as second-line analgesic and therapeutic agents in some inflammatory disorders once infection has been ruled out.
Dexamethasone is widely used for prevention of postoperative nausea and vomiting and may be administered as part of multimodal pain control for a specific surgical procedure (eg, tonsillectomy), or as an adjunct to prolong the duration of peripheral nerve blocks. (See "Anesthesia for tonsillectomy with or without adenoidectomy in children", section on 'Dexamethasone' and "Overview of peripheral nerve blocks", section on 'Adjuvants' and "Nonopioid pharmacotherapy for acute pain in adults", section on 'Glucocorticoids'.)
Intraarticular, soft tissue, and epidural glucocorticoid injections are discussed separately. (See "Intraarticular and soft tissue injections: What agent(s) to inject and how frequently?" and "Subacute and chronic low back pain: Nonsurgical interventional treatment", section on 'Glucocorticoid and other injections'.)
●Gabapentinoids – Gabapentin and pregabalin are increasingly used as part of multimodal analgesic regimens, particularly for perioperative pain control, though the literature on their effectiveness is inconclusive. (See "Nonopioid pharmacotherapy for acute pain in adults", section on 'Gabapentinoids'.)
These medications should be used cautiously in patients who chronically use opioids. Both gabapentin and pregabalin are associated with sedation and dizziness and have been associated with respiratory depression and increased mortality in patients who are also receiving opioids [31,32]. Gabapentin and pregabalin also have abuse potential. (See "Pharmacologic management of chronic non-cancer pain in adults", section on 'Gabapentin and pregabalin'.)
●Antidepressants – Serotonin-norepinephrine reuptake inhibitors and tricyclic antidepressants have been found effective for several types of chronic pain, including neuropathic pain and fibromyalgia, and may be considered for treatment of exacerbations of chronic pain. However, these drugs are rarely used for acute pain because they are not available in parenteral form and can cause cardiac conduction abnormalities if given acutely at high doses.
●Regional anesthesia – Regional anesthesia techniques are useful modalities for postoperative pain and can often be used for traumatic injuries and other localized pain. Neuraxial analgesia and/or single shot or continuous peripheral nerve blocks are discussed separately. (See "Management of acute perioperative pain in adults", section on 'Regional analgesia'.).
●Integrative therapies – Integrative therapies such as transcutaneous electrical nerve stimulation (TENS) [33], acupuncture [34-36], massage [37], hypnosis [38], a brief standardized course of cognitive-behavioral therapy, and music therapy [39] may also be useful adjuncts to medications and procedural interventions in reducing acute pain, though they have not been specifically studied in patients receiving chronic opioid therapy. (See "Rehabilitative and integrative therapies for pain in patients with cancer".)
●Psychosocial management strategies – Addressing psychosocial stressors, addressing pain-related anxiety, and providing patients with tools such as guided imagery and hypnosis [40] may be key to managing patients' acute pain. Patients who catastrophize their pain are more likely to have inadequate pain control and to develop chronic pain after an injury or surgery [41]. Clinicians can reduce catastrophizing and improve the pain experience by counseling patients about the normal pain experience, helping them feel safe despite their pain, ensuring that their concerns are addressed, and avoiding frightening language or disturbing imagery when describing the cause of pain [42]. For example, a patient with an ankle sprain can be told that they have a common injury that typically heals well, or can be told that there are microtears in muscles and ligaments. Both statements are true, but the latter is more likely to lead to pain catastrophizing, which increases distress and the risk of developing chronic pain. Preoperative education and psychologist-led interventions have been found to reduce pain catastrophizing postoperatively and may improve acute postoperative pain control [43].
Treatment of spiritual and/or existential distress, which may contribute to increased severity of pain, is discussed separately. (See "Overview of spirituality in palliative care", section on 'Approaching spiritual distress'.)
Opioids for acute pain — If pain control is inadequate with nonopioid methods of analgesia in addition to the patient's baseline opioid, and it is determined that benefits outweigh the risks, a short-acting opioid should be prescribed to supplement the patient's baseline opioid. In this context, the term "short-acting" refers to oral tablets such as hydrocodone, morphine, or oxycodone that are quickly absorbed and excreted, or any parenteral opioid agonist. Short-acting opioids such as these are better able to meet fluctuating demands for analgesia during episodes of acute pain than are extended-release or long-acting formulations of opioids.
In the context of intraoperative opioid therapy, "short-acting" typically refers to opioids such as fentanyl or alfentanil that have rapid onset and offset when infused intravenously. Remifentanil is an ultrashort-acting opioid that is rarely used outside of the operating room or on the labor floor. (See "Perioperative uses of intravenous opioids in adults: General considerations".)
Patients who chronically use opioids may be expected to have some degree of analgesic tolerance, and thus to require higher doses of opioids than opioid naïve patients, but the degree of tolerance is unpredictable. Doses of opioids should be titrated rapidly as necessary. (See 'Potentially moderate pain, anticipated duration three to five days' above and 'Potentially severe pain, anticipated duration five to seven days' above.)
Most healthy opioid-tolerant patients will not experience sedation or respiratory depression as a result of an incremental increase in opioid dose. However, some may, and this is not possible to predict accurately. Particular caution is warranted in patients who are more vulnerable to respiratory depression, including older adults, patients with sleep apnea, and pulmonary, hepatic, or renal dysfunction. (See "Prevention and management of side effects in patients receiving opioids for chronic pain", section on 'Respiratory depression'.)
The following recommendations for acute pain management apply to patients who have been maintained on opioids for chronic pain prior to the episode of acute pain. Opioid doses for patients who take methadone or buprenorphine for treatment of opioid use disorder, buprenorphine for chronic pain, and for patients who use illicit opioids are discussed separately. (See "Management of acute pain in adults with opioid use disorder".)
Oral opioids — For moderately painful events or procedures or ones that do not disrupt gastrointestinal function (eg, peripheral orthopedic procedures), the oral route often suffices for temporary augmentation of analgesia. The following is our strategy for managing acute pain with oral opioids in patients on chronic opioids for pain:
●Continue the patient's baseline opioid regimen.
●Add supplemental doses of short-acting opioids such as morphine, hydrocodone, or oxycodone as single-entity tablets or combined with a nonopioid such as acetaminophen or an NSAID. Mixed agonist and antagonist opioid analgesics, such as pentazocine, nalbuphine, and butorphanol should not be administered to patients on chronic opioid therapy, as they may displace the opioids from the mu receptor and precipitate acute withdrawal.
Opioid-tolerant patients generally require higher doses of oral opioids perioperatively than other patients. The degree of tolerance is unpredictable and is dependent on the patient's baseline opioid dose and on patient-specific metabolism and opioid receptor populations.
•If the patient is on short-acting oral opioids, we increase each dose to 150 percent of the baseline dose. As an example, a patient taking oxycodone 10 mg orally every four hours as needed chronically would be prescribed oxycodone 15 mg every four hours as needed for acute pain.
•If the patient is only on long-acting oral opioids, in addition to the baseline opioid, we start short-acting supplemental opioids, with each dose equivalent to approximately 10 percent of the total baseline daily opioid dose. As an example, for a patient who takes a total of 60 mg extended-release morphine orally per day (eg, 30 mg extended-release morphine twice daily), supplemental doses would start at approximately 10 mg (anywhere between 6 to 12 mg would be appropriate) immediate-release morphine (or the equivalent) orally every four hours.
•Titrate the dose as needed to achieve analgesia. Because these recommendations are conservative, patients may require higher doses than listed here.
•Inpatients and patients in the emergency department should be reassessed and have opioid doses adjusted frequently. After the initial dose, a second dose can be given in one hour if there is inadequate pain control and no sedation or respiratory depression. If an hour later pain control has still not been achieved, this is an indication to transition to IV pain control. For patients who will be discharged home from the emergency department, postoperative setting, or urgent care, we administer a test dose of oral opioids and monitor the response before discharge. Patients who are managed on an outpatient basis must be capable of returning or communicating with a provider by phone or email for dose adjustments within several days. Frequent dose adjustments should be expected in opioid-tolerant patients.
●Promptly initiate communication with the chronic opioid prescriber. The clinician who manages the patient's chronic pain can be instrumental in guiding acute pain treatment, predicting patient response to medications, and establishing a workable treatment plan. This clinician will also have to manage the tapering or discontinuation of supplemental opioids as acute pain subsides, and should be included in discussions about duration and setting of treatment.
●Determine a treatment duration and a taper plan, based on the expected duration of pain requiring supplemental opioids (see 'Creating a plan for treatment' above). There are little data to guide decisions about the duration of treatment for patients who chronically take opioids. We expect that patients on chronic opioids may require a longer duration of therapy and a slower taper compared with patients who are not opioid tolerant, anticipating several days of additional opioids depending upon the etiology of their acute pain and whether their current medical or surgical treatment is expected to diminish or eliminate their chronic pain. Coordination with the patient's chronic opioid prescriber can be invaluable at this stage of treatment.
•For outpatients, the duration of treatment and rate of taper, if one is needed, should be discussed with the patient at the outset of treatment. For treatment lasting less than five days, a taper is not typically required.
•For patients who have been taking opioids during hospitalization, a taper plan should be discussed with the patient prior to discharge and (following discussion if possible) communicated to the outpatient opioid prescriber. Patients with mild to moderate pain should not require more than several days of opioids for acute pain after discharge. After severely painful events, a longer duration of treatment may be required, though patients should be re-evaluated at least every two weeks if they continue to receive opioids for acute pain. In our experience, and supported by a still-evolving literature, within 14 days most acutely painful events will have resolved and patients should have returned to their baseline opioid regimen. (See 'Duration and taper of treatment with opioids' below.)
Parenteral opioids — Parenteral opioids are usually required for treatment of severe pain and may also be required for some patients with moderate pain. Opioids should be administered along with multimodal nonopioid pain control management strategies. (See 'Nonopioid strategies for pain control' above.)
Choice of opioid
●Baseline opioid – The patient's baseline long-acting oral or transdermal opioid preparation and dose should be continued if possible during the hospital stay. For patients who are unable to swallow or absorb oral medication, the oral dose can be converted to a parenteral equivalent (table 3), with a 25 percent reduction in dose to account for incomplete cross-tolerance if a different opioid is used (eg, oral oxycodone to parenteral morphine). For patients taking oral morphine or hydromorphone who are being switched to the same opioid parenterally, no dose reduction is generally needed after equianalgesic conversion (see 'Baseline opioid dose' above). If the patient is taking a long-acting oral opioid, an equivalent parenteral infusion can be administered. For example, a patient taking 30 mg of oral morphine twice a day should be started on an infusion of 0.8 mg/hour of IV morphine (60 mg/day oral morphine = 20 mg/day IV morphine = 0.8 mg/hour of IV morphine), along with as-needed opioid for the pain exacerbation.
●Additional opioid for acute pain – We suggest prescribing the IV preparation of the same opioid the patient currently takes for chronic pain (eg, IV morphine if the patient currently takes oral morphine), as this may reduce the likelihood of side effects and adverse events from a new agent.
If the patient's baseline opioid cannot be used in IV form, either because of dose-limiting side effects, formulary issues, or lack of an equivalent short-term option, another short-acting medication can be used.
●Problems with opioid conversion – There are no universally accepted standard methods for opioid conversion, and available online calculators and published conversion tables provide variable and inconsistent conversion ratios. Substantial interindividual variability in analgesic responses to the same opioid is also well-described [44]. Morphine equivalent calculations should thus only be used cautiously and conservatively as a general guide for starting doses, with modification based on patient factors such as analgesic response; age; prior opioid history; renal, hepatic, and pulmonary function; and concomitant drug therapy. Equianalgesic opioid dose conversion is discussed separately. (See "Cancer pain management with opioids: Optimizing analgesia", section on 'Equianalgesic opioid dose conversion'.)
Initial pain control — For patients with severe pain, rapid pain control should initially be sought using bolus IV administration titrated to analgesic requirements, with vigilance for respiratory depression and maintenance of hemodynamic stability, in a closely monitored setting (table 4) (see "Management of acute perioperative pain in adults", section on 'Parenteral opioids'). Patients on chronic opioid therapy may require incremental opioid doses several-fold higher than other patients; opioid doses should be titrated based upon each patient's analgesic response [45,46]. Some types of pain, eg, from an unstable fracture or abscess under pressure, are difficult to control using an opioid alone and require definitive treatment (eg, mechanical stabilization or decompression).
There is no accepted optimal protocol for opioid dose titration for acute pain in patients who chronically take opioids. Our strategy for initial pain control is as follows:
●Continue the patient's baseline home opioids (or their equivalent) as described above.
●Convert the patient's basal morphine mg equivalents to IV form. If the patient's home medications are not available in IV form, reduce the overall dose by 25 percent to account for incomplete cross tolerance. Prescribe 10 percent of that dose as a single dose for short-acting pain relief.
●Reassess in 20 to 30 minutes and if the pain score remains >3, provide a second dose 1.5 times higher than the last.
●Continue this titration until pain control has been achieved.
Ongoing pain control — Once pain is initially controlled, parenteral opioids can be administered with intermittent bolus dosing by a health care provider or via patient-controlled analgesia (PCA), with a basal rate for patients chronically receiving long-acting oral opioids. Although intermittent opioid dosing regimens administered by a clinician give the clinical staff more control over when to administer a bolus than PCA, they may lead to delay between the patient's request for analgesia and the delivery of the medication. For this reason, PCA is often the preferred strategy for ongoing management of severe pain. Intermittent clinician-administered bolus dosing is the best choice for acute pain control in patients who are unable to manage PCA, who may require rapid and closely monitored dose titration, and who have sufficient nurse staffing to provide such close attention. Multimodal nonopioid analgesic strategies should be continued along with opioid administration. (See 'Nonopioid strategies for pain control' above.)
Intermittent intravenous opioid — The following is a reasonable strategy for intermittent dosing with short-acting IV opioids (eg, morphine or hydromorphone) for acute pain in a hospital and/or emergency department, based on expert opinion and clinical experience with the management of acute pain in cancer patients [47-49]. This strategy can also be applied to patients with exacerbations of chronic non-cancer pain.
When pain control has been achieved, administer IV opioids at the dose that was found to control pain during the initial titration period every three to four hours as needed, while continuing the long-acting opioid at the patient's baseline dose or at an equivalent parenteral dose, for those unable to take oral medications.
Patient-controlled analgesia — PCA may be the best choice for acute pain control in patients who are alert and who have the capacity to press a button repeatedly to titrate analgesic drug dosing appropriately. Patients should be started on PCA only after an initial dose titration, as described above, to achieve rapid pain control before transitioning to the more metered dose administration of PCA.
PCA includes intermittent patient administered boluses at a set lockout interval, up to a maximal total dose limit per unit time. A background infusion may also be provided by PCA but basal infusion is not recommended, unless it is required to maintain baseline opioid dosing during intervals when oral or transdermal administration is not possible. If a background infusion is necessary, the hourly dose should be calculated to deliver the patient's baseline opioid consumption. For a patient who takes 60 mg oral morphine per day, the baseline IV morphine equivalent would be 20 mg per day, or approximately 0.8 mg IV per hour baseline infusion. (See "Management of acute perioperative pain in adults", section on 'Patient-controlled analgesia'.)
The initial patient-controlled bolus dose should be one-half of the patient's baseline hourly opioid requirement, with a lockout interval of 10 minutes. As an example, for a patient who usually takes 60 mg oral morphine daily, equivalent to 20 mg per day (ie, 0.8 mg/hr) IV morphine, the demand dose would be 0.4 mg morphine IV, with a lockout interval of 10 minutes. Incremental PCA bolus doses can be adjusted to accommodate the temporarily increased opioid requirement.
The importance of constant vigilance for oversedation and respiratory depression during PCA cannot be overemphasized. Cautions about concomitant use of other nonopioid drugs with the potential to depress ventilation (eg, benzodiazepines) apply equally in settings of acute as well as chronic pain. As pain intensity subsides, stimulation of respiratory drive may also decrease, so patients who are receiving basal opioids (either orally or via basal IV infusion) in combination with PCA boluses must be closely monitored for opioid sedation and respiratory depression. For example, if a surgical procedure is likely to resolve the source of round-the-clock preoperative pain such as a compressed or inflamed lumbar nerve root, it may be reasonable to discontinue the PCA and rely upon opioid-sparing multimodal analgesia supplemented by as-needed opioid boluses. Transition to an oral regimen for the (potentially decreased) basal portion of pain control should be initiated as early as tolerated by the patient.
Most patients whose pain is not refractory to opioids achieve adequate pain control with PCA bolus doses until they are able to transition to an oral regimen. In the postoperative setting, PCA represents a standard approach to pain control for patients who receive opioids. (See "Management of acute perioperative pain in adults", section on 'Patient-controlled analgesia'.)
Transition to oral opioids — Once a patient's pain is well controlled on intermittent IV or PCA opioids and the patient is able to tolerate oral medication, we transition to short-acting oral opioids. It is rarely appropriate to increase the patient's baseline dose of long-acting opioids to treat acute pain. Because most acute pain improves over the course of days to weeks, the incremental increase of a patient's opioid needs during the acute pain episode should likewise subside. Treating acute pain with short-acting opioids, with quicker onset and offset compared with long-acting opioids, facilitates appropriate dose reduction as pain improves.
The first step in transitioning from intermittent IV opioids or PCA to oral opioids is to calculate the total daily opioid consumption during the prior 24 hours, over and above the baseline maintenance opioid dose. Next, 70 percent of that 24-hour requirement should be provided through short-acting oral opioids, administered in divided doses every three to six hours depending on the opioid. In this setting, we order standing short-acting opioids that are offered to the patient at regular intervals, with the option for the patient to refuse the dose, or the clinician to withhold the dose due to sedation or respiratory depression.
Alternatively, an order may be written for short-acting opioids at regular intervals, to be given only at the request of the patient. This may lead to delays and gaps in analgesia but can also provide the patient with an increased sense of control and allow the patient to self-taper more rapidly.
Orders for PCA (bolus opioid doses only, without continuous infusion) or as-needed IV opioid may remain in place for the first day of the transition to oral opioids, to provide rescue dosing, then discontinued.
For example, a patient who is on 30 mg of morphine extended-release twice daily at baseline for chronic pain has received 46 mg of IV bolus morphine over a 24-hour period; 46 mg of IV morphine is equivalent to approximately 130 mg of oral morphine, so this patient can be transitioned to 90 mg per day of short-acting morphine (70 percent of the 24-hour bolus needs) divided every four hours. This translates to 15 mg per dose every four hours. In addition, the patient should continue to receive their baseline 30 mg of morphine twice daily for chronic pain.
Duration and taper of treatment with opioids — The duration of opioid therapy required for acute pain varies with the etiology of the pain and how it is managed. Clinicians are now revisiting discharge orders for opioids to avoid unnecessarily large or prolonged prescriptions [50,51]. Consequently, the doses and durations of opioid therapy required for acutely painful events in opioid naïve patients are being increasingly well characterized, particularly for common surgical procedures. This evidence-guided approach to postoperative opioid prescribing is discussed separately. (See "Prescription of opioids for acute pain in opioid naïve patients", section on 'Level of pain'.)
Data regarding expected opioid doses and duration in opioid naïve patients can be used as a starting point for opioid-tolerant patients, recognizing that such patients often require higher doses of opioids and longer durations of opioid therapy after procedures. Such doses and durations are often reported as medians or means and, therefore, would be expected to be inadequate if ordered for the 50 percent of patients with durations of need greater than the median. Short-acting opioids should only be prescribed for the expected duration of acute pain. If a patient's long-acting medications were increased during the acute pain episode, those should be tapered down to pre-acute pain doses or below as the cause of acute pain resolves. In patients who undergo surgery for their chronically painful condition, it may be possible to taper opioids completely off postoperatively.
Excessive discharge opioid prescribing for acute pain has led to quantities of unused opioids in home medicine cabinets, whose diversion and misuse contribute to the opioid overuse and overdose crisis. (See "Prescription of opioids for acute pain in opioid naïve patients", section on 'Excessive prescription'.) In addition, increased opioid doses postoperatively compared with baseline may be associated with increased health care costs in the following year [52].
Communication with the patient's chronic opioid prescriber is critical in determining the duration of treatment and setting a taper plan.
Naloxone prescription — For patients who chronically use opioids and are discharged from the hospital or outpatient clinic with additional short- or long-term opioids, we suggest providing a prescription for naloxone for use in case of overdose. Family or cohabitating individuals can be taught the signs of overdose and how to administer intranasal naloxone for overdose [53]. In some states, providing a prescription for naloxone, or ensuring that the patient has access to it, is legally required with opioid prescribing. The use of naloxone for prevention of opioid overdose is discussed separately. (See "Prevention of lethal opioid overdose in the community".)
MANAGEMENT OF PAIN FLARES — Many conditions have a natural history characterized by repeated flares of acute pain superimposed upon periods of stable pain. A chronic pain exacerbation may be an opportunity to introduce nonopioid treatments into a patient's pre-existing regimen, rather than increasing the baseline opioid dose. Clinicians can help identify and personalize nonopioid strategies that have not been employed or optimized for such patients. In addition to pharmacotherapy, cognitive behavioral therapy, support groups, interventional pain management, complementary therapies, and physical, occupational, and aquatic therapy can all be explored in the setting of chronic pain flares. (See "Approach to the management of chronic non-cancer pain in adults", section on 'Nonpharmacologic therapies'.)
Patients with chronic pain can benefit from developing a "flare plan" that guides their actions at the onset of a pain flare. Patients can be coached to identify their first sign of a pain flare and to develop a specific self-management plan for addressing pain flare-ups quickly and effectively. This may include taking extra as-needed opioid or nonopioid (eg, NSAID or muscle relaxant) medication, but it may also include reducing or introducing physical activity (eg, back exercises) temporarily, applying heat, ice, or topical therapies, engaging in specific self-care strategies, or connecting with support systems.
Management of pain flares is discussed in multiple topics on disorders that cause chronic pain.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Acute pain management".)
SUMMARY AND RECOMMENDATIONS
●Goals for treatment – The goals for treatment of acute pain in patients chronically using opioids are to provide adequate analgesia, to prevent withdrawal syndrome, and to avoid inducing opioid use disorder (OUD). (See 'Treatment goals' above.)
●Evaluation – Evaluation of patients with acute pain should include assessment of the cause of pain, the patient's baseline opioid dose, and the possibility of opioid use disorder. (See 'Evaluation' above.)
●General principles
•The plan for acute pain management should be based on the degree of expected pain, realizing that pain intensity and the need for opioids may be unpredictable in patients who chronically use opioids. (See 'Creating a plan for treatment' above.)
•We suggest continuing the patient's baseline opioid regimen in order to prevent withdrawal and to maintain the existing level of chronic pain control (Grade 2C). However, the baseline opioid should not be expected to be sufficient to control the present episode of acute pain. (See 'Continue the patient's baseline opioid regimen' above.)
•The plan for treatment of acute pain should start with nonpharmacologic and nonopioid strategies and add additional opioids only when anticipated or found to be necessary. Nonopioid options for acute pain control include regional anesthesia techniques, nonopioid analgesics, ketamine, lidocaine, gabapentinoids, glucocorticoids, antidepressants, and integrative or psychosocial management strategies. (See 'Nonopioid strategies for pain control' above.)
•For patients who require oral opioids in addition to their baseline chronic opioid, a short-acting opioid (eg, morphine, hydrocodone, or oxycodone) should be prescribed. Mixed agonist and antagonist opioids (eg, pentazocine, nalbuphine, or butorphanol) should not be used in known or suspected opioid-tolerant patients as these agents may precipitate acute withdrawal. (See 'Oral opioids' above.)
●Mild pain – For mild acute pain expected to last one to two days, nondrug therapies (eg, heat, cold, or splinting) and nonopioid analgesics (eg, acetaminophen, nonsteroidal antiinflammatory drugs [NSAIDs]) in addition to the patient's baseline chronic opioid usually provide adequate analgesia. (See 'Potentially mild pain, anticipated duration one to two days' above.)
●Moderate pain – Moderate pain that usually lasts three to five days often requires a few days of short-acting opioids in addition to the patient's baseline chronic opioid and nonopioid analgesic strategies. (See 'Potentially moderate pain, anticipated duration three to five days' above.)
●Severe pain
•Severe pain should be controlled rapidly by titrating IV opioids. After initial control of severe pain, ongoing pain control can be accomplished with intermittent clinician-administered IV opioid boluses, or patient-controlled analgesia (PCA). (See 'Initial pain control' above and 'Ongoing pain control' above.)
•Severe pain expected to last five to seven days can sometimes be managed primarily with continuous regional anesthesia techniques. For patients in whom regional anesthesia is not possible, multimodal analgesia including parenteral opioids in the hospital are usually required until the pain subsides to the point at which oral opioids can be used. For patients who require parenteral opioids, we suggest prescribing the intravenous (IV) preparation of the same opioid the patient currently takes for chronic pain (eg, IV morphine if the patient currently takes oral morphine) (Grade 2C), to reduce the likelihood of side effects and adverse events from a new agent. (See 'Potentially severe pain, anticipated duration five to seven days' above.)
●Post discharge care – Opioid therapy should be coordinated with the patient's chronic opioid prescriber. For patients who chronically use opioids and are discharged from the hospital or outpatient clinic with additional short- or long-term opioids, we suggest providing a prescription for naloxone for use in case of overdose (Grade 2C). (See 'Naloxone prescription' above.)
ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Diana Coffa, MD, who contributed to earlier versions of this topic review.
