Most cases of stomach flu (viral gastroenteritis) last 1 to 3 days. The exact duration depends on which bug caused it, your age, and your overall health. Some infections stretch closer to a week, and lingering digestive symptoms can stick around even longer after the worst is over.
Duration by Cause
Norovirus is the most common cause of stomach flu in adults. Symptoms typically hit 12 to 48 hours after exposure and resolve within 1 to 3 days. During that window, vomiting and watery diarrhea can be intense, sometimes occurring many times a day, but the illness burns through quickly.
Rotavirus, the leading cause in young children, tends to last longer: 3 to 8 days of vomiting and watery diarrhea. Adults who catch rotavirus usually have milder symptoms and recover faster than kids do. Vaccination has made severe rotavirus much less common in countries with routine childhood immunization.
Bacterial infections that mimic the stomach flu can also fall in this range. Campylobacter, one of the more frequent bacterial culprits, causes symptoms that start 2 to 5 days after exposure and typically clear within 7 days. Salmonella follows a similar pattern, usually resolving in 4 to 7 days without treatment. If your symptoms last beyond a week or include bloody diarrhea, a bacterial cause is more likely than a straightforward virus.
What the Timeline Actually Feels Like
The first 12 to 24 hours are usually the worst. Nausea, vomiting, and diarrhea hit hard and often come with chills, body aches, and a low-grade fever. Many people can barely keep sips of water down during this phase.
By day 2 or 3, vomiting usually tapers off first. Diarrhea often lingers a bit longer, sometimes persisting for a day or two after vomiting stops. Your appetite may stay suppressed, and you’ll likely feel wiped out even after the vomiting and diarrhea end. This is normal. Your body just burned through a lot of energy and fluids fighting off the infection.
Most people feel noticeably better by day 4 or 5, though full energy levels can take another few days to bounce back. If you’re still dealing with frequent vomiting or diarrhea past day 3 for norovirus, or past day 8 for rotavirus, that’s outside the typical range.
Why Some People Take Longer to Recover
Infants, older adults, and people with weakened immune systems tend to have more prolonged and severe illness. Their bodies are slower to clear the virus and more vulnerable to dehydration, which can itself delay recovery. Hospitalization for IV fluids is sometimes necessary in these groups.
Even in otherwise healthy adults, the recovery phase can feel surprisingly drawn out. Fatigue, reduced appetite, and mild nausea may linger for a week or more after the acute symptoms resolve. Some people describe a foggy, run-down feeling that doesn’t match how “over it” they expected to be. This post-viral fatigue is a real phenomenon. Most people recover fully, but it can occasionally take several weeks before energy levels return to normal.
Lingering Gut Symptoms After Recovery
Here’s something that catches many people off guard: a bout of stomach flu can temporarily change how your digestive system works, even after the infection is completely gone. Loose stools, bloating, cramping, and food sensitivities can persist for weeks as your gut lining heals and your intestinal bacteria rebalance.
In a smaller but significant group, these symptoms become more persistent. Roughly 14.5% of people who go through a bout of gastroenteritis develop post-infectious irritable bowel syndrome (IBS). A BMJ analysis found that among those who developed IBS after a stomach infection, about half still had symptoms 6 to 11 months later, and around 40% still experienced symptoms beyond 5 years. This doesn’t mean the stomach flu itself lasts that long. It means the infection can trigger a lasting shift in gut function for some people. If you’re still having irregular bowel habits months after your illness, it’s worth mentioning to your doctor rather than assuming something is still “going around.”
How Long You Stay Contagious
You’re most contagious while you have symptoms and for at least 48 hours after they stop. With norovirus specifically, viral shedding can continue for two weeks or more after recovery, though the risk of spreading it drops significantly once vomiting and diarrhea end. The practical takeaway: stay home for at least two full days after your last episode of vomiting or diarrhea, wash your hands thoroughly (hand sanitizer is less effective against norovirus), and avoid preparing food for others during that window.
Signs That Something More Serious Is Happening
Most stomach flu resolves on its own. But dehydration can turn a routine illness into a dangerous one, especially at the extremes of age. In adults, warning signs include being unable to keep any liquids down for 24 hours, vomiting or diarrhea lasting more than two days, blood in your vomit or stool, severe abdominal pain, dark yellow urine or very little urine output, dizziness, and fever above 104°F.
In children, the signals are slightly different. Watch for:
- No tears when crying or a dry mouth
- No wet diaper in six hours for infants
- Unusual drowsiness or irritability beyond what you’d expect from feeling sick
- Sunken eyes or, in infants, a sunken soft spot on the head
- Bloody diarrhea or frequent vomiting that won’t let up
A reassuring sign in kids: if they’re still drinking normally, urinating at their usual rate, and not vomiting, dehydration is very unlikely to be a concern. The combination of all three of those markers essentially rules out significant fluid loss.