| Historical clues | Implications |
| Pattern of initial onset |
| Abrupt | Suggests infectious/postinfectious or drug- or dietary-induced diarrhea. |
| Gradual | Can be seen in many disorders, including IBD and functional diarrhea. |
| Potential triggers |
| Dietary changes |
| Initial onset after a change from breast milk to formula or from formula to unmodified cow's milk | Possible food protein-induced allergic proctocolitis or enterocolitis (usually related to cow's milk). |
| Initial onset after an increase in dietary fructose, sucrose, or lactose or poorly absorbed carbohydrates (eg, sorbitol, xylitol) | Multiple possible mechanisms: - High intake may cause osmotic diarrhea (dose-related) or exacerbate functional diarrhea.
- Temporary disaccharidase deficiency (eg, postinfectious).
- Permanent disaccharidase deficiency. Physiologic lactase nonpersistence (hypolactasia) is common; other disaccharidase deficiencies are rare.
|
| Onset coincided with introduction of gluten (eg, in wheat, rye, or barley) | Possible celiac disease. In severe cases, onset of symptoms may occur within weeks to months after gluten is introduced (or increased) but may occur at any time thereafter. |
| Infectious exposures |
| Onset after acute diarrheal illness (in index patient or close contacts) | Infectious or postinfectious diarrhea. Postinfectious diarrhea often varies with diet (eg, exacerbated by lactose). |
| Recent travel, particularly to equatorial/tropical countries with endemic enteric pathogens | Potential prolonged enteric infection or postinfectious diarrhea. |
| Recent visit to campgrounds; water supply from well | Consideration of parasitic exposure (eg, G. lamblia). |
| Drugs |
| Onset associated with the use of certain drugs (eg, antibiotics, SSRIs) | Possible drug-related side-effect*. |
| Physical symptoms |
| Bloating symptoms | Suggests abnormality of carbohydrate assimilation or small intestine bacterial overgrowth. |
| Nausea/vomiting | Suggests intestinal inflammation (including FPIES) or impaired motility. |
| Diarrhea pattern |
| Postprandial episodes | Suggests food intolerance or functional diarrhea (eg, IBS-D). |
| Nocturnal episodes | Suggests an organic disorder with a component of abnormal electrolyte absorption/secretion. One exception is that young children with functional diarrhea sometimes have very low-volume nocturnal episodes of diarrhea. |
| Stool appearance |
| Blood and/or mucus | Food protein-induced proctocolitis (eg, due to cow's milk), IBD, prolonged enteric infection (eg, C. difficile). |
| Light tan or white | Absence of bile, suggesting biliary obstruction. Occasionally found in celiac disease. |
| Family history |
| Family history of autoimmunity, IBD, or other significant systemic or gastrointestinal disorders | Increases the likelihood of heritable diseases, including celiac disease and IBD (both relatively common) or any other polygenic and monogenic disorders (rare). |
| Signs/symptoms suggesting underlying medical illnesses |
| History of recurrent, persistent, or opportunistic infections or immunodeficiency diagnosis | Possible immunodeficiency, immune-mediated diarrhea, or graft-versus-host disease. |
| Growth faltering or weight loss | Malabsorption, pancreatic exocrine insufficiency, anorexia nervosa. |
| Intravenous drug use or other risk factors | HIV disease. |
| History of chronic constipation and/or fecal incontinence | Possible retentive (constipation-associated) fecal incontinence (misinterpreted as diarrhea by the patient/family). |
