Most cases of stomach flu (viral gastroenteritis) last one to three days, with the worst symptoms typically peaking within the first 24 hours. You should feel noticeably better within two to three days of your first symptoms appearing. Some cases, particularly those caused by rotavirus, can stretch to eight days, but that’s the upper end rather than the norm.
The First 48 Hours: What to Expect
After you’re exposed to a stomach virus like norovirus, the most common culprit, symptoms typically hit within 12 to 48 hours. The onset is often sudden: one moment you feel fine, and within an hour or two you’re dealing with nausea, vomiting, watery diarrhea, or all three at once.
The active vomiting phase is usually the shortest part. In experimental studies of norovirus infection, the median duration of all signs and symptoms was just 23 hours, with a range of 10 to 61 hours. That means for most people, the truly miserable stretch of vomiting and cramps is essentially a one-day event. Diarrhea often lingers a bit longer than the vomiting, sometimes continuing for a day or two after your stomach has settled.
Timeline by Cause
The specific virus matters. Norovirus, which causes the majority of stomach flu cases in adults, resolves the fastest. Most people recover within one to three days. Rotavirus, more common in young children, tends to drag on longer, with vomiting and watery diarrhea lasting three to eight days.
Bacterial infections from contaminated food (think Salmonella or E. coli) can mimic the stomach flu but sometimes last longer or require treatment. In general, though, the Cleveland Clinic notes that the most common types of gastroenteritis only last a day or two, and your body can overcome most infections on its own. A good rule of thumb: if symptoms persist beyond five days, something else may be going on and it’s worth contacting a healthcare provider.
You’re Still Contagious After You Feel Better
This is the part most people don’t realize. Even after your symptoms completely resolve, you can still spread the virus for two weeks or more. In one CDC-supported study, norovirus was detectable in stool samples for a median of four weeks after infection, and in some cases up to eight weeks. The highest concentrations of virus in stool were actually found after symptoms had already resolved, meaning you’re shedding the most virus right when you feel well enough to resume normal life.
The practical takeaway: stay home for at least 48 hours after your last episode of vomiting or diarrhea. That’s the CDC’s official recommendation, and it applies to workplaces, schools, and especially anyone who handles food. Food service workers are specifically required to stay away from duties for a minimum of 48 hours after symptoms stop. Even after returning to your routine, thorough handwashing remains important for weeks.
Eating and Drinking During Recovery
Dehydration is the main medical risk with stomach flu, not the virus itself. When you’re vomiting frequently or having watery diarrhea, you’re losing fluids and electrolytes fast. Small, frequent sips of water, broth, or an oral rehydration solution are more effective than drinking large amounts at once, which can trigger more vomiting.
There’s no need to follow an elaborate refeeding schedule. The National Institute of Diabetes and Digestive and Kidney Diseases advises that once your appetite returns, you can go back to eating your normal diet, even if you still have some diarrhea. The old advice about sticking to bananas, rice, applesauce, and toast (the BRAT diet) isn’t harmful, but it’s no longer considered necessary. For children, the same principle applies: give them what they normally eat as soon as they’re willing to eat again. Restricting their diet doesn’t speed recovery.
Signs That Something More Serious Is Happening
Most stomach flu cases resolve without any medical intervention. But certain warning signs suggest you should seek medical advice:
- Duration: Vomiting that lasts more than one to two days, or diarrhea that continues beyond three to four days
- Dehydration: Dark urine, dizziness when standing, dry mouth, or in children, no wet diapers for several hours
- Blood in vomit or diarrhea
- Severe abdominal pain or a persistent high fever
- Underlying conditions: Diabetes, kidney disease, inflammatory bowel disease, or a weakened immune system all raise the stakes
Elderly adults and very young children are at the highest risk for dangerous dehydration and should be watched more closely. For an otherwise healthy adult, though, the typical stomach flu is a short, intense illness that peaks quickly and clears within a few days.