Diarrhea: Causes, Medicine, What to Eat and When to Worry

Diarrhea means loose, watery stools (loose motions) three or more times in a day. Most bouts come from a stomach bug or something you ate, and they clear up on their own in 1 to 3 days. The main danger is losing too much fluid, so drinking enough is the most important part of treatment.

Key points

Viruses such as norovirus cause most short bouts of diarrhea in adults and children.
Sip water, broth or an oral rehydration drink often. Plain water alone may not replace lost salts.
Eat bland foods as soon as you feel like it. You don’t need to stop eating.
Loperamide or bismuth subsalicylate can help adults with watery diarrhea, but avoid them with fever or bloody stools.
See a doctor for blood in the stool, high fever, signs of dehydration, or diarrhea lasting more than 2 days.

How diarrhea happens

Each day, the intestines handle several quarts of fluid from food, drinks and digestive juices. Normally they soak almost all of it back up, so stool comes out formed. Diarrhea happens when that balance fails. Germs and their toxins can make the gut lining pour out fluid. Inflammation can damage the lining so it absorbs less. Some foods, such as lactose in milk or sugar alcohols in sugar-free gum, pull water into the bowel. And when the gut moves too fast, there isn’t time to absorb the water. The result is watery stool.

What causes diarrhea

Short-term diarrhea (less than 2 weeks)

Viruses, mainly norovirus, and rotavirus in children who haven’t had the vaccine
Bacteria from undercooked meat, eggs, unwashed produce or unsafe water, such as Salmonella, Campylobacter, Shigella and some types of E. coli
Food poisoning from toxins. This can start within a few hours of eating and often brings sudden vomiting.
Parasites such as Giardia, often from lake or stream water
Travel to places with different water and food hygiene
Medicines, especially antibiotics, metformin and magnesium-based antacids
Alcohol, caffeine and sugar substitutes such as sorbitol

Antibiotics can let a germ called C. difficile take over the colon. It causes frequent, smelly diarrhea that needs specific treatment.

Long-term diarrhea (more than 4 weeks)

Lasting diarrhea needs a doctor’s check. Causes include irritable bowel syndrome (IBS), lactose intolerance, celiac disease, Crohn’s disease, ulcerative colitis, microscopic colitis, an overactive thyroid and problems with the pancreas.

What the color and type of stool can mean

Explosive diarrhea comes out suddenly and forcefully with gas. It is common with norovirus and food poisoning and usually settles within a day or two.
Yellow or green diarrhea often means stool moved through too fast for bile to turn it brown. Greasy, pale or floating stools that smell very bad can point to Giardia, celiac disease or a pancreas problem.
Sudden watery diarrhea without cramps is often from a virus, a medicine or something you ate. You still need extra fluids.
Black, tarry, or bloody stools need prompt medical care. Bismuth subsalicylate and iron pills can turn stool black without bleeding.

How to stop diarrhea at home

Drink to replace fluids

Take small, frequent sips if you feel sick to your stomach.
An oral rehydration solution, sold in drugstores as a liquid or powder, has the right mix of salt, sugar and water. It is the best choice for children and older adults.
Broth, water and diluted juice help too. Sports drinks are fine for healthy adults with mild diarrhea.
Avoid sodas, energy drinks, full-strength fruit juice, alcohol and lots of coffee. They can make diarrhea worse.

Keep breastfeeding or formula feeding babies, and give an oral rehydration solution between feeds if your doctor advises.

What to eat with diarrhea

Good choices are bland and easy to digest:

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Bananas, applesauce and canned peaches
White rice, noodles, toast, crackers and oatmeal
Boiled or baked potatoes
Soup, eggs and plain chicken or fish
Yogurt with live cultures, if dairy agrees with you

The old BRAT diet (bananas, rice, applesauce, toast) is too limited to follow for more than a day. Go back to your usual foods as you feel better.

Foods that tend to make diarrhea worse:

Fried, greasy or very fatty foods
Spicy dishes
Sugar-free candy and gum
Large glasses of milk or ice cream, if you’re sensitive to lactose
Beans, cabbage and other foods that cause a lot of gas

Medicine for diarrhea

Loperamide (Imodium) slows the gut and is the most common medicine for loose motions in adults. Don’t use it for bloody diarrhea, a high fever, or after recent antibiotics, and don’t give it to young children unless a doctor says so.
Bismuth subsalicylate (Pepto-Bismol) eases diarrhea and upset stomach. It can turn your tongue and stool black. Don’t give it to children or teens, and avoid it if you take blood thinners or are allergic to aspirin.
Antibiotics only help some bacterial and parasite infections. They don’t work on viruses. Your doctor may prescribe one for severe traveler’s diarrhea, C. difficile or a confirmed infection.
Probiotics may shorten some bouts a little or help prevent diarrhea from antibiotics. The evidence is mixed, and they aren’t advised for people with weak immune systems.

Follow the package directions, and stop if symptoms get worse.

Lowering your risk

Wash your hands with soap and water after using the toilet and before handling food. Hand sanitizer doesn’t kill norovirus well.
Cook meat and eggs fully, wash produce and keep raw meat apart from other foods.
When traveling, drink bottled or treated water and eat foods that are cooked and served hot.
Make sure babies get the rotavirus vaccine.
Stay home from work or school until 48 hours after a stomach bug ends, especially if you handle food.

When to see a doctor

Diarrhea for more than 2 days in an adult, or more than a day in a child
Fever of 102°F (38.9°C) or higher
Blood or pus in the stool, or black stools
Severe belly pain
Diarrhea after taking antibiotics, a hospital stay or travel abroad
You are pregnant, over 65, or have a weak immune system, kidney disease or heart disease

Get emergency care for signs of serious dehydration: little or no urine for 8 hours, dizziness or fainting, a racing heart, confusion or extreme sleepiness. In babies and young children, watch for no wet diaper in 3 hours or more, crying without tears, a dry mouth, sunken eyes, or being unusually sleepy or fussy.

Common questions about diarrhea

Does a heating pad or warm compress help diarrhea?

Warmth on the belly won’t stop diarrhea, but it can ease cramps and make you more comfortable. Use a heating pad on low or a warm (not hot) compress over a cloth, for 15 to 20 minutes at a time. Don’t sleep on a heating pad, and focus on drinking fluids.

How long does diarrhea last?

Most short-term diarrhea from a virus or food lasts 1 to 3 days. Some bacterial infections last up to a week, and parasites such as Giardia can last longer without treatment. Diarrhea that goes on for more than 2 days in an adult, or keeps coming back, needs a doctor’s check.

Why do I get diarrhea after drinking alcohol?

Alcohol irritates the gut lining, speeds up the bowel and reduces how much water the colon absorbs. Sugary mixers, caffeine and greasy late-night food add to the effect. Hangover diarrhea usually settles within a day. If it happens after every drink, or with belly pain, see a doctor.

Is yellow diarrhea serious?

Usually not. Yellow diarrhea most often means food moved through quickly, which is common with a stomach bug. It is more concerning if it is greasy, floats, smells very bad or lasts for weeks. That can mean Giardia, celiac disease or a liver, gallbladder or pancreas problem.