Patient education: Blood donation and transfusion (Beyond the Basics)

INTRODUCTION — Blood is essential for transporting oxygen, nutrients, and other substances to tissues throughout the body. Donated blood can be lifesaving for individuals who have lost blood because of accidents or surgery, as well as for people who have become severely anemic or have dangerously low platelet counts because of certain medical conditions and/or treatments, such as chemotherapy to treat cancer. Screening measures help to maximize safety of blood donation for the donor and the recipient.

For people who are considering donating blood, a local blood collection center can describe the criteria for being a blood donor. The websites at the end of this topic also include information about eligibility criteria, which may vary slightly between different blood collection centers (see 'Where to get more information' below). People who have a pre-existing medical condition may wish to consult their own health care provider.

DONATING BLOOD DURING THE COVID-19 PANDEMIC — Coronavirus disease 2019 (COVID-19) is a disease caused by a virus called SARS-CoV-2. The virus first appeared in late 2019 and has since spread throughout the world.

During the pandemic, people in many areas are being told to stay home (and avoid contact with other people) as much as possible. While this is very important to slow the spread of the virus, it also means that fewer people are donating blood. Because of this, there might not be enough blood available for people who need it. If you are healthy and able to give blood, now is a very important time to do it.

You can donate blood if you have received a COVID-19 vaccine. You can also donate if you have been sick with COVID-19, once you have recovered and two weeks have gone by since your last symptoms.

In some cases, people who previously were ineligible to donate blood may now be able to do so. This is discussed in more detail below. (See 'Screening for infections' below.)

You can find information online about where to give blood in your area. During the COVID-19 pandemic, some places where you can normally give blood might be closed, and other places might be holding blood drives. You can find out more through the following resources:

●Your community blood center

●The American Red Cross (www.redcrossblood.org or 1-800-733-2767)

●Vitalant (www.vitalant.org/ or 1-877-258-4825)

●America's Blood Centers (americasblood.org/ or 202-393-5725)

●Association for the Advancement of Blood & Biotherapies (AABB; www.aabb.org or 301-907-6977)

If you are sick with COVID-19 or have symptoms like a fever or cough, do not try to give blood. Donated blood is not tested for the virus that causes COVID-19, and you should not donate blood as a way to get tested. If you do have the infection, being around other people puts them at risk of getting sick, too.

MEASURES TO PROTECT THE DONOR — Several measures are used to ensure that blood donation is safe for the donor and is unlikely to have any negative health effects.

Medical history interview — All blood donors are asked questions about their medical history to help determine whether they can safely donate blood without experiencing any negative health effects.

●Heart, lung, and blood disease – Potential donors are asked if they have ever had heart, lung, or blood diseases. People with heart disease, heart valve conditions, irregular heartbeat, disease of the blood vessels in the brain, heart failure, and certain lung conditions may be excluded from blood donation, or they may be allowed to donate blood provided this has been cleared with their health care provider and they have had no major symptoms in the prior six months. Certain blood diseases such as iron deficiency anemia or chronic leukemia may also lead to exclusion.

●Other medical conditions – Potential donors are asked if they feel healthy and well on the day of donation. A prospective donor should mention other serious medical conditions to the donor health historian who will then evaluate eligibility to donate.

●Seizures – People with a history of seizures can donate blood, provided they have had no seizures within a certain period of time (usually one to six months).

●Recent surgery – People who have undergone recent surgery are permitted to donate blood when healing is complete and they have resumed full activity. However, if a transfusion was given at the time of surgery, donation is not allowed for one year.

●Pregnancy – Donating blood is not permitted during pregnancy and for six weeks after a pregnancy ends.

●Age requirement – The minimum age for blood donation is 16 or 17 years, depending upon the state. When allowed, 16-year-olds must bring a signed permission form from a parent. In most cases, there is no upper age limit for donation, although approval from the donor's clinician is required in some cases.

●Weight requirement – Individuals weighing less than 50 kg (110 pounds) are not permitted to donate blood. The less a donor weighs, the greater the likelihood of having a reaction such as dizziness and fainting following donation. Although reactions to blood donation are rare, individuals weighing between 50 and 54 kg (110 and 119 pounds) are most likely to experience reactions. Most blood centers perform an additional evaluation of donors aged 16 to 18 who are just over the weight limit, which takes into account the donor's estimated blood volume, calculated from the donor's height and weight. There is no upper weight limit for donating blood, although some centers have an upper weight limit based on the size/weight limit of the donor phlebotomy chair.

Questions are also asked that address the safety of the transfusion for the person receiving the blood, such as the possibility of getting an infection from the transfusion. (See 'Screening measures to protect the recipient' below.)

Medical evaluation — In addition to a medical history, donors undergo a brief physical examination before donation to check for any obvious signs of illness or conditions that would disqualify them from blood donation.

●Vital signs – The pulse, blood pressure, and temperature of a donor are checked before donation. Individuals with a fever, high blood pressure (generally higher than 180/100), very high or very low heart rate (with the exception of highly conditioned athletes and those on beta blocker medication), or an irregular heartbeat are temporarily not permitted to donate blood.

●Blood test – A small blood sample is taken from a fingerstick and tested to check for the amount of hemoglobin in the blood. This is done to ensure that the donor is not anemic or likely to become anemic after they donate. Individuals with hemoglobin levels that are too low are temporarily not permitted to donate blood. (See "Patient education: Anemia caused by low iron in adults (Beyond the Basics)".)

Donation procedure — During the donation, the donor is seated comfortably in a chair, and a needle is put in the arm to remove the blood. This is done slowly enough so that possible symptoms such as lightheadedness are minimized. One unit of blood is removed (approximately 500 mL or about a pint). The person is monitored during the donation and given some juice or other liquids or snacks afterwards.

Time interval until next donation — According to US Food and Drug Administration (FDA) regulations, donors are eligible to donate no sooner than 56 days (eight weeks) after their previous whole blood donation. However, not all donors will be able to qualify at this minimum interval, as it depends upon how rapidly the person's body is able to replenish its red blood cells. For example, people who have heavy menstrual periods will not be able to donate every 56 days because their iron stores are not sufficient to replenish the lost red blood cells.

Iron deficiency — Donating blood removes iron from the body, and this can result in iron deficiency if iron stores are already low. The risk of iron deficiency is highest in teenage donors, premenopausal females, and individuals who donate frequently (three or more times a year). Because the strategy of eating iron-rich foods is not sufficient to replenish lost iron, many blood collection organizations recommend that people at increased risk for iron deficiency take a multivitamin with iron or an iron-only supplement for approximately 60 days to replace the iron lost through each blood donation.

APHERESIS DONATION — A technology called apheresis has made it possible to collect specific components of blood. Apheresis is used to selectively collect red blood cells, platelets (blood components that play an important role in clotting), plasma, and granulocytes (a type of infection-fighting white blood cell). The procedure is done in the blood center or at a blood drive and involves inserting a needle in a vein in each arm. Blood is withdrawn through one needle, passed through an apparatus that separates plasma from specific types of blood cells (platelets or red blood cells) and retains the desired component, and then the remainder of the blood is returned to the donor through the other needle. It takes from one to two hours.

The different components of blood include:

●Plasma – This is the liquid part of blood in which the cells are suspended.

●Red blood cells – Donors can give red blood cells by apheresis once every 16 weeks. This is less frequent than whole blood donation because a greater number of red blood cells are collected during the apheresis procedure.

●Platelets – Donors can give platelets up to 24 times per year. Approximately 1 percent of people have a mild reaction to one of the substances (citrate) that is mixed with the blood during platelet donation; the reaction can include feelings of numbness and tingling, muscle cramping, and nausea. The blood collection center closely monitors for any reactions, and these can be easily treated or prevented by taking a calcium supplement before or during the donation.

●Granulocytes – Donors of granulocytes may be given granulocyte colony-stimulating factor (G-CSF) and/or a glucocorticoid medication called dexamethasone on the day before donation to increase the number of granulocytes in their blood. Glucocorticoids are usually not given to individuals who have diabetes, gastrointestinal ulcers, or glaucoma. The side effects of G-CSF and dexamethasone may include headache, joint pain, fatigue, insomnia, allergic reactions, and fever.

SCREENING MEASURES TO PROTECT THE RECIPIENT — Screening of blood donors helps to ensure that the donated blood is safe for transfusion into a recipient.

●Screening questionnaire and laboratory testing for possible infections – A variety of different measures, including a questionnaire for self-reporting of infectious exposures and other infectious disease risk factors are used for this screening. A sample of the blood is tested in the laboratory for a variety of infections. (See 'Screening for infections' below.)

●Elimination of payment for donation – Since the late 1970s, volunteer donors have been the source of all whole blood and blood components in the United States. In rare instances where donors are paid, the donated components undergo additional treatment to kill any infectious agents that might be in the product. These are referred to as "pathogen inactivation" treatments.

Screening for infections — Potential blood donors are asked a number of questions about things that may increase their risk of certain infectious diseases, such as their travel history, past drug use, and sexual behavior. In some cases, this information makes a person ineligible to donate blood, either for a specific period of time or indefinitely. In April 2020, the United States Food and Drug Administration (FDA) changed some of the criteria for donation as a response to the COVID-19 pandemic and concerns about a decrease in the national blood supply. The specific changes are discussed in more detail below. (See 'Human immunodeficiency virus (HIV)' below and 'Parasitic diseases' below and 'Prion diseases' below.)

Donated blood is tested for certain viruses and bacteria that can cause infections, but it is not tested for SARS-CoV-2 (the virus that causes COVID-19). Respiratory viruses like this are not known to be transmitted through blood transfusions. Even so, people should not try to donate blood if they have a fever or symptoms of a respiratory illness such as a cough. (See 'Donating blood during the COVID-19 pandemic' above.)

Other infections, and the related screening measures, are discussed in the following sections.

Human immunodeficiency virus (HIV) — Human immunodeficiency virus (HIV) is the virus that causes AIDS. A variety of measures are used to screen donors for HIV infection or risk factors for HIV, including questions about any signs or symptoms of HIV and behaviors that increase the risk of HIV. Such behaviors include using non-prescription intravenous (IV) drugs, having sex with a prostitute or in exchange for money or drugs, getting a tattoo in a facility that does not use fresh needles for each person, and for males, having sex with another male. Depending on your answers to these questions, you may need to wait for a period of time before you are eligible. In April 2020, the criteria in the United States changed as a result of the COVID-19 pandemic; now, the requirement is to wait at least three months after participating in behaviors that could increase the risk of HIV.

Donated blood is tested for HIV. However, people who want to be tested for HIV or other sexually transmitted infections should not donate blood for this purpose. Laboratory tests are not perfect and there is a small possibility that a person who might have been exposed to HIV could transmit the virus to a recipient if they donate blood. Free and anonymous HIV testing is available; there is a searchable database for testing sites on HIV.gov.

Hepatitis — Hepatitis is a viral infection that causes inflammation of the liver. Blood donors are routinely screened to determine whether they have been exposed to (or infected with) the hepatitis B virus or the hepatitis C virus.

●People who have had sexual contact or have lived in the same dwelling (eg, house, dormitory) with someone who has hepatitis B or hepatitis C are disqualified for 12 months after their last exposure to that person, depending upon the particulars of the exposure. A similar deferral is applied in the case of exposure to people with viral hepatitis of unknown origin.

●People who have ever had a confirmed positive test for hepatitis B surface antigen (a marker for hepatitis B virus infection) are permanently disqualified from donating blood. Hepatitis B vaccination may temporarily cause this test to become positive. To avoid being disqualified as a blood donor, a person who has recently received the hepatitis B vaccine should wait 21 days before donating blood. At that time, this test should be negative. Donors with false positive or vaccine-induced positive hepatitis B surface antigen results can be requalified to donate if the blood center follows a stringent protocol and a sufficient amount of time has elapsed.

●Donors are not asked if they have ever had viral hepatitis. However, if a person volunteers the information that they previously had hepatitis B or C, most blood centers will defer such donors, since a positive laboratory test would require the donated blood to be destroyed.

●In the event that a community is experiencing an ongoing outbreak of hepatitis A, temporary deferral procedures for exposure to this agent could be put in place.

●People who have received a blood transfusion are not permitted to donate blood for 12 months after the date of transfusion.

●In some states, people who have received a tattoo are not permitted to donate blood for 12 months. In many other states, where the tattooing industry is carefully regulated by state law to ensure that the procedures are sterile, donation may be permitted without the need for any waiting period. With regard to ear or body piercing, donation is allowed if the procedure was performed with sterile or single-use equipment.

Donated blood is tested for the hepatitis B and C viruses.

Zika virus — Zika virus causes a mild infection in most people, but if a pregnant person is infected, the virus can cause miscarriage or serious brain abnormalities in the baby. Laboratory testing of donated blood for Zika virus was started in the United States in the summer of 2017 but has been discontinued as there is no longer an active Zika epidemic in the Americas.

Parasitic diseases — Blood donors are routinely asked questions about possible exposure to several diseases caused by parasites that can be transmitted by blood transfusion.

●Malaria – Transfusion-transmitted malaria is common in some parts of the world but is extremely rare in the United States. Donors who have had malaria are not permitted to donate for three years after they become free of symptoms. People who have lived (usually defined as at least five years) in countries where malaria is common are not permitted to donate for three years after their departure from that country. Travelers who have visited regions where malaria occurs are not permitted to donate blood for three months after they leave the area, provided they have not had symptoms of malaria. This was changed from a one-year waiting period in April 2020 during the COVID-19 pandemic.

●Chagas disease and babesiosis – Transmission of Chagas disease (American trypanosomiasis) by transfusion is rare in the United States. Blood donors are asked if they have ever had Chagas disease, and donated blood from first-time donors is tested for Chagas disease.

Transmission of babesiosis (a malaria-like illness spread by ticks) by transfusion is uncommon. Blood donors are asked if they have ever had this disease. In regions of the United States where babesiosis is more common, blood may be tested for it.

Prion diseases — Creutzfeldt-Jakob disease (CJD) is a rare but fatal neurologic disease. Variant Creutzfeldt-Jakob disease (vCJD, the human form of "mad cow disease") is a related but distinct disease that first appeared in the United Kingdom (UK) in 1996. Affected individuals may have no symptoms of CJD or vCJD for many years. The infectious agent of both these diseases is an abnormally folded protein called a prion.

To date, there have been no reported cases of transfusion-related transmission of CJD and only four reports of probable transmission of vCJD in the UK. Despite the extremely small risk, donors who meet one or more of the following criteria are not allowed to donate:

●Have ever been diagnosed with vCJD, or

●Have spent ≥3 cumulative months in the UK from 1980 to 1996, or

●Have spent ≥5 cumulative years in France or Ireland from 1980 to 2001, or

●Received a blood transfusion in the UK, France, or Ireland between 1980 to present

These criteria used to be more restrictive prior to April 2020. They were revised during the COVID-19 pandemic.

Bacterial infection — Certain bacteria normally live on the skin and in the digestive tract. Bacteria can get into donated blood if a donor has a bacterial infection, if bacteria on the skin gets into the blood from the needle stick, or if there is a skin infection near the location where the blood is drawn. To reduce the likelihood of bacterial contamination of blood, the skin around the site is carefully examined and cleaned before the needle is inserted.

Donors who have a fever, who do not feel well, or who are taking oral antibiotics (except for acne) are not permitted to donate blood. These restrictions also apply to individuals who are banking blood for their own use. (See 'Autologous blood donation' below.)

Other infections — Donated blood cannot be tested for every possible infection, and new types of infections are frequently emerging around the world. The pre-donation educational material given to donors, as well as the questionnaire, includes several general questions that are designed to identify individuals who either have infection symptoms or who have travelled to locations where these infections are more common. These questions are directed at general signs of infection, and individuals who might be at risk of transmitting an infection due to travel or behaviors are asked to "self-defer" (to avoid donating blood). The decision to self-defer can be made at the time of donation or after the donation has been completed (in which case the blood collection center will not use or distribute the donated blood).

In addition, the blood center educational materials inform donors that they should call the blood center if specific medical symptoms that could indicate an active infection develop in the two weeks following donation; this is done so that the donated unit can be removed from the blood supply.

Other medical conditions — To protect the recipient against non-infectious complications, the donor is evaluated for certain medical conditions before blood donation.

●Cancer – There have been no reported cases of the transmission of cancer by blood transfusion. However, because such transmission is theoretically possible, donors are screened for a history of cancer.

Donors who have had cancer of a solid organ or tissue (such as the lung, liver, breast) are permitted to donate if they have been symptom- and cancer-free for a period of time off of treatment as defined by the blood collection facility. This time period varies but is at least one year.

Donors who have had blood cancers (such as leukemia or lymphoma) are permanently disqualified from donating.

Donors who have had a superficial cancer that has been completely removed by surgery (such as basal cell cancer of the skin or early cervical cancer) can donate blood without any waiting period.

●Hemochromatosis – Individuals with hereditary hemochromatosis (a genetic condition in which frequent removal of blood is the standard treatment) can donate their blood for transfusion if they meet other criteria for being a donor and if the blood bank has met certain regulations from the FDA. The acceptance of blood donations from these individuals has not been uniformly implemented, perhaps due to the costs of meeting regulations and removing financial incentives to blood donation.

There is no risk of transmitting hemochromatosis to the recipient. (See "Patient education: Hereditary hemochromatosis (Beyond the Basics)".)

Recent vaccinations — There are strict standards for when you can donate blood after you have received a vaccination. When you go to donate blood, you will be asked if you have had any recent vaccinations. If you have, you might have to postpone your blood donation.

For some live or attenuated (weakened) viral or bacterial vaccines (measles, mumps, oral polio, oral typhoid, yellow fever), you have to wait at least two weeks before donating your blood. For rubella or varicella zoster vaccines, you have to wait four weeks.

Medications — Most medications taken by donors do not pose a risk to recipients. However, a number of drugs are known to cause birth defects, and questions about use of these medications are part of donor screening. Donors who have taken these medications are asked to wait the indicated times after their last dose before donating:

●Etretinate (brand name: Tegison), used for psoriasis – Indefinite (do not donate)

●Acitretin (brand name: Soriatane), also used for psoriasis – Three years

●Isotretinoin (brand names: Absorica, Amnesteem, Claravis, Myorisan, Zenatane; formerly known as Accutane in the United States), used for acne – One month

●Finasteride (brand names: Propecia, Proscar), used for benign prostatic hypertrophy or hair loss – One month

●Dutasteride (brand name: Avodart), usually given for prostatic enlargement – Six months

●Vismodegib (brand name: Erivedge), used for basal cell skin cancer – Two years

Medications that affect parts of the blood clotting system also may lead to temporary inability to qualify for some types of blood donation.

●People who took aspirin or aspirin-containing medications within the previous 48 hours are allowed to donate whole blood but are not allowed to donate platelets by apheresis.

●People who took anti-platelet drugs (eg, clopidogrel [sample brand name: Plavix] or ticagrelor [sample brand name: Brilinta]) must wait a variable period ranging from 2 to 14 days to donate platelets by apheresis.

●People who took anti-clotting medications (also called "blood thinners") are generally not allowed to donate blood for a minimum of two days after the last dose. These include dabigatran (brand name: Pradaxa), rivaroxaban (brand name: Xarelto), apixaban (brand name: Eliquis), edoxaban (brand names: Savaysa, Lixiana), and low molecular weight heparin products (given by injection; sample brand name: Lovenox). People who took warfarin (sample brand name: Jantoven) are asked to wait seven days before donating.

Laboratory testing of donated blood — After a unit of blood has been donated, the blood is tested in a laboratory for infectious diseases that can be transmitted by blood transfusion. These include tests for HIV, hepatitis B virus, hepatitis C virus, human T-lymphotropic virus (HTLV), West Nile virus, and syphilis. In addition, some blood donations may be tested for babesiosis, Chagas disease, and/or Zika virus. (See "Patient education: West Nile virus infection (Beyond the Basics)".)

Registry of deferred donors — A registry of deferred donors contains names of individuals who have been disqualified from blood donation in the past, usually due to being at risk for or having specific infectious diseases, such as hepatitis B or HIV infection. Theoretically, it is possible that an individual with one of these diseases could have a positive test result at one time but negative test results at a later time.

A donor's name is usually checked against this registry before permitting the donation to take place. The reason for the deferral is not usually available to staff at the collection facility.

Telephone callbacks — After donating blood, donors are given a phone number so that they can call the donation center to report any factors that may affect the use of their blood or to report symptoms of infections in the first days to two weeks after donating (such as symptoms of upper respiratory tract infection, gastrointestinal illness, or infection with a virus transmitted by mosquitos). Such reports will be evaluated, and the unit of blood may be destroyed.

RISK OF INFECTION FROM A TRANSFUSION — Safety measures such as improved screening tests have dramatically reduced the risk of acquiring a viral infection from a blood transfusion. The likelihood of getting one of these infections from a blood transfusion is lower than the likelihood of dying in a car crash or of being killed by a firearm.

Estimates of the risks of developing certain infections after receiving a unit of blood in the United States include the following:

●1 in 1 million to 1 in 1.5 million for hepatitis B virus

●1 in 2 million to 1 in 2.6 million for hepatitis C virus

●1 in 1.6 million to 1 in 2.3 million for human immunodeficiency virus (HIV)

The ranges are provided because different blood organizations have slightly different estimates.

OTHER RISKS FROM A TRANSFUSION — In addition to the risk of infection, minor risks from transfusion include the following:

●Allergic reactions to proteins and/or cells in the transfusion

●Fever due to fever-causing proteins (cytokines) in the transfusion. These reactions are called febrile nonhemolytic transfusion reactions (FNHTRs)

There are also other risks that are much rarer but are more serious. These include:

●Shortness of breath due to immune/inflammatory reactions, known as transfusion-associated acute lung injury (TRALI)

●Shortness of breath due to the large volume of fluid, known as transfusion associated circulatory overload (TACO)

●Immune attack of the recipient by the transfused cells, called transfusion-associated graft-versus-host disease (ta-GVHD)

●Blood incompatibility, leading to destruction of the transfused cells by the recipient's immune system

These conditions occur infrequently and are well known to clinicians; measures are taken routinely to minimize them further.

AUTOLOGOUS BLOOD DONATION — Autologous blood donation is when a donor donates blood for their own use several days to six weeks ahead of a scheduled surgery, when blood might be needed. Autologous blood donation reduces the risk of most, but not all, infectious complications of blood transfusion. However, transfusions using blood donated from another person (allogenic blood transfusions) are one of the most common and safest medical procedures. Autologous blood donation is rare.

POTENTIAL COMPLICATIONS OF BLOOD DONATION — Most people who donate blood do not have any complications that require medical care. The most common complications include bruising or soreness at the needle site and fatigue.

A small percentage (2 to 5 percent) of blood donors feel faint and/or pass out before, during, or after donating blood. This is more common the first time a person donates and in people who are younger. Drinking a 16-ounce (473 mL) bottle of water before donating and/or eating a salty snack may reduce this risk.

WHERE TO GET MORE INFORMATION — Your health care provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: Blood donation (giving blood) (The Basics)
Patient education: Blood transfusion (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: West Nile virus infection (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Clinical use of plasma components
Blood donor screening: Laboratory testing
Blood donor screening: Overview of recipient and donor protections
Blood donor screening: Medical history

The following organizations also provide reliable health information:

●National Library of Medicine – medlineplus.gov/healthtopics.html

●National Heart, Lung, and Blood Institute – www.nhlbi.nih.gov/

●American Red Cross – www.redcross.org

●America's Blood Centers – www.americasblood.org

●Association for the Advancement of Blood & Biotherapies(AABB) – www.aabb.org