Acute Diarrhea: Causes, Treatments, and What to Do When It Strikes

When you suddenly have watery stools that won’t stop, you’re dealing with acute diarrhea, a short-term digestive issue lasting less than two weeks, often caused by infection or food intolerance. It’s not just uncomfortable—it can be dangerous if you lose too much fluid too fast. This isn’t a minor inconvenience. Millions of people in the U.S. get it every year from contaminated food, viruses like norovirus, or even new antibiotics that upset their gut bacteria.

Dehydration, the body losing more water than it takes in, often from frequent bowel movements and vomiting is the real threat. Signs? Dry mouth, dizziness, dark urine, or not peeing for 8 hours. Kids and older adults are at highest risk. The fix isn’t fancy: oral rehydration, a simple mix of water, salt, and sugar that replaces lost fluids and electrolytes works better than soda, juice, or plain water. You can buy it premade at any pharmacy, or make your own with a pinch of salt and a teaspoon of sugar in a liter of clean water.

Many reach for loperamide, an over-the-counter anti-diarrheal that slows bowel movements right away. It can help you feel better fast, but it’s not always the right move. If your diarrhea is caused by bacteria or parasites—like from undercooked meat or travel to a high-risk area—slowing things down might trap the bad bugs inside. Let your body flush them out unless you’re severely uncomfortable or need to travel. Always check with a pharmacist if you’re on other meds—loperamide can interact with heart drugs or antidepressants.

Most cases of acute diarrhea clear up on their own in a day or two. But if it lasts longer than 48 hours, you have blood in your stool, a fever over 102°F, or you’re dizzy and can’t keep fluids down, you need to see someone. Antibiotics? Rarely needed. They’re only for confirmed bacterial infections, and even then, only if you’re at risk for complications.

You’ll find posts here that cover the hidden causes—like how a new antibiotic can wipe out your good gut bacteria, or why lactose intolerance can suddenly show up after an infection. There’s also advice on what to eat (bananas, rice, toast—not greasy food), how to keep kids hydrated without IVs, and when to skip the anti-diarrheal pills entirely. You’ll see real cases: someone who got sick after a road trip, a parent who thought their toddler had a virus but actually had a food allergy, and how to tell if it’s just a bad stomach bug or something more serious.

This isn’t about panic. It’s about knowing what to do before it gets worse. Acute diarrhea is common, but it doesn’t have to be scary—if you know the signs, the safe fixes, and when to call for help.