Gastroenteritis (stomach flu): what to do right away

Stomach pain, sudden diarrhea, vomiting — that’s gastroenteritis. Most cases come on fast and are caused by viruses, not bacteria. If you or someone in your family feels wiped out by nausea and watery diarrhea, these clear steps will help you manage symptoms and avoid complications.

First, focus on fluids. Vomiting and diarrhea can dehydrate you in hours. Drink small, frequent sips of water, clear broth, or an oral rehydration solution (ORS). A simple homemade ORS mixes 6 teaspoons sugar and half a teaspoon salt into 1 liter of clean water. Sports drinks help sometimes but can be too sugary for kids. If fluids come back up, try ice chips or half-teaspoon sips every few minutes.

Next, watch food. Skip heavy, greasy meals while symptoms are active. Start with bland options: toast, plain rice, bananas, applesauce — the classic BRAT approach works for a short time. Gradually return to normal foods as appetite and stools normalize. Avoid dairy, caffeine, alcohol, and fatty foods for 48 hours after symptoms ease.

Medications: what helps and what to skip

For adults, over-the-counter loperamide (Imodium) can reduce diarrhea when needed, but avoid it if you have a high fever or bloody stools — those signs may mean a bacterial infection that needs a doctor. Antiemetics can control severe nausea; options like ondansetron or domperidone are used in some cases, but you should ask a clinician before taking them. Acid reducers such as pantoprazole (Protonix) don’t treat gastroenteritis itself and aren’t a quick fix for vomiting or diarrhea.

Antibiotics are rarely needed. Most gastroenteritis is viral and clears on its own. Your doctor may prescribe antibiotics if tests show a specific bacterial cause or if a person is very ill or immunocompromised. If you want to read more on when antibiotics are used for belly infections, check our article about antibiotics for acute cholecystitis for related ideas.

When to see a doctor

Call a clinician if you have signs of severe dehydration (very little urine, dizziness, very dry mouth), a fever over 38.5°C (101.3°F) that won’t come down, bloody diarrhea, severe belly pain, or symptoms that last more than 48–72 hours. Babies, older adults, and people with weakened immune systems need earlier evaluation.

Prevention is simple: wash hands often, disinfect shared surfaces, avoid preparing food for others while sick, and keep up-to-date with vaccines for rotavirus in infants. Traveling? Be cautious with street food and tap water in high-risk areas.

Gastroenteritis usually resolves in a few days with the right fluids and rest. If you’re unsure about medicines or dehydration, talk to a healthcare provider. If you want practical drug guides, our site has helpful articles on nausea options and acid reducers to help you decide what to ask your doctor.

Got specific symptoms or a child who’s sick? Reach out to a health professional quickly — that’s the fastest way to avoid complications.