Diarrhea means loose, watery stools three or more times a day. A short bout is usually caused by a stomach bug or something you ate, and it passes with rest and fluids. Diarrhea that lasts for weeks is different: it almost always has a specific cause, and finding it is the key to feeling better. Dr. Pimienta evaluates and treats diarrhea for adults across Los Angeles County.
Call 911 or go to the nearest emergency room if you have signs of severe dehydration, such as confusion, fainting, a racing heart or making very little urine; black or bloody stools with dizziness; vomiting blood; severe or worsening belly pain; or a high fever with belly pain.
Is my diarrhea short-term or chronic?
How long diarrhea lasts helps point to the cause:
- Acute
- Lasts a day or two. Usually an infection or something you ate.
- Persistent
- Lasts 2 to 4 weeks. Worth calling your doctor.
- Chronic
- Lasts 4 weeks or more, or keeps coming back. Needs an evaluation.
What causes diarrhea?
Short-term causes
- Infections from viruses (such as norovirus), bacteria (food poisoning) or, less often, parasites.
- Medicines, especially antibiotics. Diarrhea during or after antibiotics can sometimes be caused by an infection called C. difficile (C. diff), which needs testing and treatment.
Causes of chronic diarrhea
- Medicines and supplements: magnesium, metformin, some blood pressure and diabetes medicines, and sugar-free products with sorbitol or similar sweeteners. GLP-1 medicines for diabetes and weight loss can also affect the bowels (see our article on GLP-1 medicines and your digestion).
- Lactose intolerance: trouble digesting the sugar in milk, causing gas, bloating and diarrhea after dairy.
- Celiac disease: an immune reaction to gluten, a protein in wheat, barley and rye, that damages the small intestine.
- Inflammatory bowel disease: Crohn's disease and ulcerative colitis, often with blood, urgency or weight loss. See inflammatory bowel disease.
- Microscopic colitis: inflammation that can only be seen under a microscope. It causes watery diarrhea, is more common in older adults, and the colon usually looks normal during colonoscopy, so biopsies are needed to find it.
- IBS with diarrhea (IBS-D): diarrhea with belly pain linked to bowel movements. See irritable bowel syndrome.
- Bile acid diarrhea: extra bile acids reach the colon and pull water in. It is more common after gallbladder removal or bowel surgery.
- Less common causes, such as an overactive thyroid, pancreas problems or long-lasting infections.
What are the signs of dehydration?
Diarrhea drains water and salts from the body. Older adults, people with heart or kidney problems, and people who are also vomiting can become dehydrated quickly. Watch for:
- Strong thirst and a dry mouth
- Dark yellow urine, or urinating much less than usual
- Feeling tired, weak or dizzy, especially when you stand up
- Headache or muscle cramps
Drink fluids that contain salts and sugar, such as an oral rehydration solution from the pharmacy, broth, or diluted juice. Plain water alone does not replace lost salts. If you cannot keep fluids down, or you have the severe signs in the box at the top of this page, get care right away.
When should I see a GI doctor for diarrhea?
See a doctor if diarrhea lasts more than two days, and make an appointment with a GI doctor if:
- It has lasted four weeks or more, or keeps coming back
- It wakes you up at night
- You see blood or mucus, or stools are black
- You have lost weight without trying
- It started during or after antibiotics, a hospital stay or travel
- You have a family history of celiac disease, IBD or colon cancer
How does Dr. Pimienta find the cause?
Your history gives the biggest clues: when it started, what your stools look like (watery, greasy, bloody), whether it happens at night, what you eat and drink, recent travel or antibiotics, and every medicine and supplement you take. After an exam, Dr. Pimienta chooses tests that fit your story:
- Blood tests, such as a blood count, a celiac disease test, thyroid tests and markers of inflammation.
- Stool tests for infections, including C. diff and parasites, and for inflammation in the bowel.
- Other tests that may be arranged, such as a breath test for lactose intolerance.
- Colonoscopy with biopsies to look for inflammation, microscopic colitis and other causes in the colon.
- Upper endoscopy (EGD) with biopsies of the small intestine when celiac disease or another small-bowel problem is suspected.
Keep eating gluten until you are tested. If celiac disease is possible, do not start a gluten-free diet before your blood test or endoscopy. Going gluten-free first can make the tests look normal when they are not.
How is diarrhea treated?
Short-term diarrhea is usually treated with fluids, rest and simple foods. For adults without fever or blood in the stool, over-the-counter loperamide can ease symptoms. Bismuth subsalicylate can help too; it can turn stools black, which is harmless, and it should be avoided if you are allergic to aspirin. Ask a doctor before using either if you have bloody stools or a fever.
Chronic diarrhea is treated by treating its cause. Examples include cutting back on lactose, a strict gluten-free diet for celiac disease, medicines that calm inflammation in IBD or microscopic colitis, medicines that bind bile acids, targeted IBS treatments, changing a medicine that is causing the problem, and antibiotics for certain infections. Your plan depends on your health. You and Dr. Pimienta decide together what fits you, and follow-up visits confirm that it is working.
A note on travel
If diarrhea starts during or after a trip, tell Dr. Pimienta where you went. Travelers' diarrhea usually clears in a few days. Diarrhea that lasts for weeks after a trip can point to a parasite such as Giardia, and stool tests can find it.
Questions patients ask
How long is too long for diarrhea?
For adults, see a doctor if diarrhea lasts more than two days. Diarrhea lasting four weeks or more is called chronic and should be evaluated, ideally by a GI doctor.
Should I take loperamide?
It can help with mild diarrhea in adults. Do not take it if you have a fever or blood in your stool unless a doctor tells you to, because it can keep an infection in the bowel longer.
Can diarrhea come from my medicines?
Yes, often. Antibiotics, magnesium, metformin, GLP-1 medicines and sugar-free sweeteners are common examples. Bring a full list of your medicines and supplements to your visit, and do not stop a prescribed medicine without talking to your doctor.
Why take biopsies if my colon looks normal?
Some causes of chronic diarrhea, such as microscopic colitis, can only be seen under a microscope. That is why a colonoscopy done for chronic diarrhea usually includes biopsies even when the colon looks normal.
Could it be lactose intolerance?
It may be, especially if symptoms follow dairy. Trying lactose-free milk for two weeks is a simple first test. If symptoms continue, there is likely another cause to look for.
References
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Diarrhea.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Microscopic Colitis.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Celiac Disease.
- American College of Gastroenterology. Diarrheal Diseases: Acute and Chronic (patient information).