Recurring diarrhea that won’t go away usually points to something your body is reacting to on a regular basis, whether that’s a food, a medication, an underlying digestive condition, or lingering effects from a past infection. If your diarrhea has lasted less than a week, it’s considered acute and will likely resolve on its own. Diarrhea lasting two to four weeks is classified as persistent, and anything beyond four weeks is chronic, which means something specific is driving it.
Foods That Quietly Cause Ongoing Diarrhea
Diet is one of the most common and most overlooked reasons for recurring loose stools. The culprit isn’t always obvious, because the foods involved are ones many people eat every day without problems.
Sugar alcohols are a frequent trigger. These are sweeteners found in sugar-free gum, protein bars, diet drinks, and many “keto” or “low-sugar” packaged foods. Common ones include sorbitol, xylitol, and erythritol. Your gut absorbs these very slowly, and when too much sits in the intestine, it pulls water in from surrounding tissue, creating watery stools. This isn’t a disease or allergy. It’s a straightforward physical response to unabsorbed sugar sitting in your gut. Sorbitol can cause problems at doses as low as 10 to 20 grams per day, which is easy to hit if you’re chewing several pieces of sugar-free gum or eating multiple protein bars. Erythritol is better tolerated and rarely causes issues at normal amounts.
Fructose malabsorption is another common cause. Some people can’t fully absorb the natural sugar in fruit, honey, agave, and high-fructose corn syrup. In one study of patients with unexplained gut symptoms, 64% turned out to be fructose malabsorbers. A hydrogen breath test can confirm it, and people with confirmed malabsorption often see significant improvement on a fructose-reduced diet. Lactose intolerance works through the same mechanism: unabsorbed lactose draws water into the intestine and ferments, producing gas, bloating, and diarrhea.
If your diarrhea follows meals but you can’t pin down a specific food, a low-FODMAP elimination diet (which temporarily removes fermentable sugars including fructose, lactose, and sugar alcohols) can help identify what your gut is reacting to.
Medications That Cause Diarrhea as a Side Effect
If your diarrhea started or worsened after beginning a new medication, that’s a strong clue. Metformin, one of the most widely prescribed diabetes drugs, is notorious for causing loose stools, especially in the first weeks of use. NSAIDs like ibuprofen and naproxen can irritate the gut lining and trigger diarrhea with regular use. Proton pump inhibitors (the heartburn drugs like omeprazole and pantoprazole) can also cause it, though less commonly. Antibiotics are another well-known trigger because they disrupt the balance of bacteria in your gut, sometimes leading to diarrhea that persists for weeks after you finish the course.
If you suspect a medication, don’t stop it without talking to your prescriber, but do bring it up. Switching to a different formulation or an alternative drug often resolves the problem entirely.
Post-Infection Diarrhea That Lingers
A bout of food poisoning or stomach flu can leave lasting changes in your gut. About 1 in 9 people who get infectious gastroenteritis go on to develop a condition called post-infectious IBS, where diarrhea, cramping, and urgency continue long after the original infection clears. At 12 months after the initial illness, roughly 10% of people still meet the criteria for IBS, and that number actually rises slightly beyond the one-year mark.
The infection appears to change gut motility, sensitivity, and the composition of gut bacteria in ways that persist. If your recurring diarrhea started after a clear episode of food poisoning or traveler’s diarrhea, this is a likely explanation. Post-infectious IBS tends to improve gradually over time, and dietary changes (particularly reducing fermentable carbohydrates) can help manage symptoms in the meantime.
Bile Acid Diarrhea
Your liver produces bile acids to help digest fat. Normally, your intestine reabsorbs most of them at the end of the small bowel. When that recycling system doesn’t work properly, excess bile acids flood the colon and trigger watery, urgent diarrhea. This condition, called bile acid diarrhea, causes frequent bowel movements, urgency that can wake you at night, excessive gas, and abdominal pain. Up to 30% of people diagnosed with diarrhea-predominant IBS actually have bile acid diarrhea as the underlying cause.
It’s worth knowing about because it’s significantly underdiagnosed, and it responds well to specific treatment. If your diarrhea is especially urgent, worsens after fatty meals, and tends to be yellow or lighter in color, bring this possibility up with your doctor.
Conditions That Need Investigation
Several chronic conditions cause persistent diarrhea as a primary symptom. Irritable bowel syndrome (diarrhea-predominant type) is the most common functional cause, meaning the gut works abnormally without visible damage. Inflammatory bowel diseases like Crohn’s disease and ulcerative colitis involve actual inflammation and ulceration of the intestinal lining. Celiac disease, an immune reaction to gluten, damages the small intestine and impairs nutrient absorption.
Microscopic colitis is a particularly sneaky diagnosis. Your colon looks completely normal during a standard colonoscopy, but biopsies reveal inflammation that’s only visible under a microscope. It’s most common in people over 50, especially women, and often appears alongside autoimmune conditions or after starting a new medication. The hallmark symptom is persistent, watery diarrhea without blood.
Hyperthyroidism (an overactive thyroid) can also speed up your digestive system and cause chronic loose stools, along with weight loss, anxiety, and a rapid heart rate.
Signs That Need Prompt Attention
Most cases of recurring diarrhea have a manageable, non-dangerous cause. But certain features signal something more serious:
- Blood or pus in your stool
- Fever accompanying the diarrhea
- Unintentional weight loss
- Diarrhea that wakes you from sleep
- Signs of dehydration (dark urine, dizziness, dry mouth)
Nighttime diarrhea is particularly significant because functional conditions like IBS almost never wake you up. Diarrhea that disrupts sleep tends to point toward an inflammatory or structural cause that warrants testing.
Staying Hydrated While You Figure It Out
Chronic diarrhea doesn’t just cause discomfort. It depletes water, sodium, and potassium faster than most people realize. Drinking plain water helps but doesn’t replace electrolytes. The WHO’s oral rehydration recipe, which you can make at home, is more effective: combine 3/8 teaspoon of salt, 1/4 teaspoon of potassium-based salt substitute, 1/2 teaspoon of baking soda, and about 2.5 tablespoons of sugar in one liter of water. The sugar isn’t for flavor. It activates a transport mechanism in your intestine that pulls sodium and water into your bloodstream far more efficiently than water alone.
Narrowing Down Your Cause
Start by looking at patterns. Does the diarrhea follow meals, or is it random? Does it happen after specific foods, or after eating anything at all? Did it start after an infection, a new medication, or a period of high stress? Is it worse in the morning, or does it wake you at night?
A two-week food and symptom diary is one of the most useful tools you can bring to a medical appointment. Track what you eat, when symptoms hit, and what your stools look like. Stools that are mushy with ragged edges (type 6 on the Bristol Stool Scale) or entirely liquid with no solid pieces (type 7) both count as diarrhea. Noting the pattern and consistency gives your doctor far more to work with than simply saying “I keep having diarrhea.”
Basic blood work, stool tests for inflammation and infection, and sometimes a breath test for sugar malabsorption can rule out many causes quickly. If those come back normal and symptoms persist, a colonoscopy with biopsies (to check for microscopic colitis and inflammatory bowel disease) is typically the next step.