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Diarrhea: what it is, the causes, staying hydrated, what to eat, the tests, treatment, and when to get help
For anyone with diarrhea, a day of it or weeks of it, for anyone caring for a baby, a child or an older adult who has it, and for the people who help them. It passes on, by name, what the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK, part of the NIH) says about diarrhea: what it is, the kinds and the signs; the causes, from infections and travel to food intolerances and other conditions; how doctors find the cause; what to drink and eat, over-the-counter medicine for adults, and what doctors do; and the signs of dehydration and when to get help right away. It builds the questions to ask and prints a card. Nothing is saved.
A word with a dotted line under it, like this, opens its official definition, quoted from a U.S. government glossary.
Right now
- Confused, very sleepy or hard to wake, fainting, or cannot keep any liquid down and barely urinating? Call 911 (ours).
- Black or bloody stool, severe belly or rectal pain, a lot of vomiting, or signs of dehydration? A baby younger than 12 months with diarrhea? NIDDK says to talk with a doctor right away. Get care today (ours).
- At the end of your rope, or having thoughts of suicide? Call or text 988, any hour, free (ours).
More help
- For children: Vomiting and diarrhea in a baby or child · Chronic diarrhea in children.
- The causes on this site: Food poisoning · Lactose intolerance · IBS · Celiac disease · Crohn’s disease · Colonoscopy · Belly and stomach: find the right page.
- For you: My medicines · Caring for someone · Low-cost health care · Get ready for your appointment. In an emergency: Help right now (988, 911). All our free tools.
An upset stomach, and not sure this is the right page? The pages on this site for throwing up, diarrhea, heartburn and constipation, on one list.
This page and its wording were written with AI (Claude) for Scarlet Beast (our AI policy). No doctor or nurse has reviewed it. The facts were read on October 22, 2026 on NIDDK’s (NIH) page Diarrhea, every section, last reviewed in September 2024. Ours: the 911 and 988 lines; going to urgent care or an emergency room when the doctor cannot be reached the same day; reading the label and asking the pharmacist; writing down what happened before the visit; the questions to ask; the card; the links to our other pages; and the order of the steps. What we left out: its clinical trials section, its references, its acknowledgment, the homemade oral rehydration recipe it links to, and the other pages it links to, which we did not read. Nothing you tick or type here is saved or sent.