Diarrhea: Causes, Relief, and When to See a Doctor

Common causes of diarrhea

Diarrhea is a symptom, not a disease, so the real question is what is driving it. Most short bouts trace back to an infection or something you ate, while diarrhea that keeps coming back usually has a deeper cause in the gut, liver, or pancreas.

Infections and food

• Stomach bugs: Viral and bacterial gastroenteritis is the leading cause of sudden, watery diarrhea, often with nausea and cramps.
• Contaminated food: Food poisoning from bacteria or their toxins can hit within hours of eating.
• Travelers' diarrhea: New water and food bacteria abroad commonly trigger several days of loose stools.
• Stomach lining irritation: Gastritis and infections like Helicobacter pylori can upset digestion.

Food intolerances and digestion problems

• Lactose intolerance: Lactose intolerance causes gas, bloating, and diarrhea after dairy.
• Celiac disease: Celiac disease is an immune reaction to gluten that damages the small intestine.
• Bacterial overgrowth: Small intestinal bacterial overgrowth and malabsorption syndromes keep nutrients and water from being absorbed.

Chronic gut conditions

• IBS: Irritable bowel syndrome is a top cause of recurring diarrhea, cramping, and urgency, often tied to stress or certain foods.
• Inflammatory bowel disease: Crohn's disease and ulcerative colitis cause ongoing diarrhea that may carry blood.
• Pouches in the colon: Diverticulitis and diverticulosis can shift bowel habits.
• Growths: Colon polyps sometimes change stool patterns.

Liver, gallbladder, and pancreas

When bile and digestive enzymes are off, fat is poorly absorbed and stools turn loose, greasy, or pale. Causes include gallstones, bile duct stones, pancreatitis, and liver problems such as hepatitis, hepatitis A, hepatitis B, hepatitis C, fatty liver disease, and cirrhosis.

Medications are an easy-to-miss trigger. Antibiotics, certain antacids, and some diabetes drugs all loosen stools. If diarrhea started soon after a new prescription, mention it to your doctor before stopping anything.

When to seek emergency or urgent care

Most diarrhea is not dangerous, but certain warning signs mean you should not wait it out. The biggest risks are dehydration and a serious underlying cause, and both can move quickly, especially in young children, older adults, and people with weakened immune systems.

Go to the emergency room or call 911 if you have:

• Diarrhea with severe or constant belly pain that does not let up
• Blood in your stool, black tarry stool, or stool that looks like coffee grounds
• A high fever above 102 degrees Fahrenheit
• Signs of serious dehydration: dizziness or fainting, a racing heart, very little or no urine, sunken eyes, or extreme weakness
• Confusion, trouble staying awake, or inability to keep any fluids down

Call your doctor within a day if you have:

• Diarrhea lasting more than two days in an adult, or more than 24 hours with a fever
• Six or more loose stools in 24 hours
• Signs of mild dehydration such as a very dry mouth, dark urine, or strong thirst
• Diarrhea during pregnancy that is severe, bloody, or comes with cramping

Infants and young children get dehydrated fast. Call a pediatrician right away if a child has diarrhea with no wet diaper in three hours, a dry mouth, no tears when crying, sunken eyes, a sunken soft spot on the head, or unusual sleepiness. When in doubt with a baby, do not wait.

How to get relief and self-care

For ordinary diarrhea, the goal is simple: replace what you lose and let your gut settle. The single most important step is staying hydrated, because watery stools pull fluid and salts out of your body fast.

Replace fluids and electrolytes

• Sip water, broth, or diluted juice steadily throughout the day rather than gulping large amounts at once.
• Use an oral rehydration solution or a sports drink to replace lost sodium and potassium. For children, a pediatric electrolyte solution is best.
• Avoid alcohol, very sugary drinks, and a lot of caffeine, since they can pull more water into the gut.

Eat gently as you recover

• Start with bland, easy foods such as bananas, rice, applesauce, toast, plain crackers, and boiled potatoes.
• Add foods back slowly as your stomach calms down, and skip greasy, spicy, or very high-fiber meals for a day or two.
• If dairy seems to make things worse, hold off on milk products until you feel better.

Over-the-counter medicine

Anti-diarrheal medicines like loperamide can slow things down and help you get through a long day, and bismuth subsalicylate can ease cramping and nausea. These work well for plain, watery diarrhea in adults. Do not use them if you have a high fever or bloody stools, because slowing the gut can trap a harmful infection inside. Do not give anti-diarrheal medicines to children without a doctor's guidance, and check with a pharmacist if you take other prescriptions or are pregnant.

How diarrhea is diagnosed

For a short bout, no testing is needed and you simply recover. When diarrhea is severe, bloody, or hangs on for weeks, a doctor looks for the cause with a few straightforward steps.

It usually starts with questions and an exam. Your doctor will ask how long it has lasted, how often you go, what the stool looks like, what you have eaten, where you have traveled, and what medicines you take. This history alone often points to the answer.

From there, testing is matched to your clues:

• Stool tests check for bacteria, parasites, hidden blood, or signs of inflammation.
• Blood tests look for infection, dehydration, celiac disease, thyroid problems, and how your liver and pancreas are working.
• Breath tests can identify lactose intolerance or bacterial overgrowth.
• Colonoscopy or upper endoscopy lets a gastroenterologist see the gut lining directly and take small samples when inflammatory bowel disease, celiac disease, or growths are suspected.

Keeping a simple food and symptom diary before your visit can speed this up considerably. Note what you ate, when diarrhea hit, and anything that made it better or worse. That record often saves time and points your doctor toward the right test on the first try.

When to see a doctor and which specialist

See a doctor if your diarrhea lasts more than a few days, keeps coming back, wakes you at night, or comes with weight loss, blood, or ongoing belly pain. These patterns suggest something beyond a passing bug and deserve a proper look.

Your primary care doctor is the right first stop and handles most cases, including ordering initial stool and blood tests. If diarrhea is chronic, bloody, or unexplained, you will likely be referred to a gastroenterologist, a specialist in the digestive system who can perform endoscopy and manage conditions like inflammatory bowel disease, celiac disease, and chronic infections.

This page is educational and is not a diagnosis. Only a clinician who can examine you and review your history can tell you what is truly causing your symptoms and what treatment fits you best. If anything here matches what you are feeling, use it as a starting point for that conversation, not a replacement for it.

When you are ready to find care, you can search for board-certified digestive specialists near you and compare their training, locations, and the insurance they accept.

Diarrhea in special situations

A few groups need extra care because their bodies handle diarrhea differently.

During pregnancy

Short spells of diarrhea in pregnancy are common and often tied to hormone shifts, diet changes, or prenatal vitamins. Focus on fluids and rest, and call your doctor before taking any anti-diarrheal medicine. Reach out promptly if diarrhea is severe, bloody, lasts more than a day or two, or comes with fever or strong cramping, since dehydration affects both you and the baby.

In babies and young children

Children lose fluids quickly, so dehydration is the main worry. Offer an oral rehydration solution and keep feeding as tolerated. Watch closely for dry mouth, no tears, fewer wet diapers, sunken eyes, or unusual sleepiness, and call a pediatrician if any of these appear. Bright green stool in a newborn is often normal, but if it comes alongside any of those warning signs, call right away.

After eating

If diarrhea reliably follows meals, look for a pattern. Dairy points toward lactose trouble, gluten toward celiac disease, and a mix of foods plus stress toward IBS. Pinning down the trigger with a food diary gives your doctor a strong head start.

Frequently Asked Questions

Medical disclaimer: This content is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about a medical condition. If you have a medical emergency, call 911. Our editorial standards