Most cases of stomach flu (viral gastroenteritis) last 1 to 3 days. Norovirus, the most common cause in adults, typically clears within one to two days after symptoms start. Rotavirus, which hits young children hardest, tends to last longer at 3 to 8 days. In unusual cases, symptoms can linger for up to 14 days.
Timeline From Exposure to Recovery
Stomach flu doesn’t hit the moment you’re exposed. There’s a gap between picking up the virus and feeling sick. For norovirus, that incubation period is 12 to 48 hours. Rotavirus takes slightly longer, with symptoms appearing 1 to 3 days after contact.
Once symptoms begin, most people follow a rough pattern. Nausea and vomiting usually come first and are most intense in the first 12 to 24 hours. Diarrhea often overlaps with or follows the vomiting phase and can continue for a day or two after the vomiting stops. Muscle aches, headache, and low-grade fever may come and go throughout. By day two or three, most adults are through the worst of it, though fatigue and a weak appetite can hang around a bit longer.
What Symptoms to Expect
The hallmark symptoms of stomach flu are watery diarrhea, nausea, vomiting, and stomach cramps. The diarrhea is almost always nonbloody. If you notice blood in your stool, that typically points to a different and more serious infection worth getting checked out.
Other common symptoms include low-grade fever, muscle aches, and headache. These tend to be milder than the gut symptoms and resolve around the same time. Unlike the respiratory flu (influenza), stomach flu centers on the intestines, not the lungs or sinuses, so coughing and congestion aren’t part of the picture.
How Long You’re Contagious
Here’s the part most people don’t expect: you can spread norovirus for two weeks or more after you feel completely better. The virus continues to shed in stool long after your symptoms resolve. This is why stomach flu tears through households, daycare centers, and cruise ships so effectively.
Thorough handwashing with soap and water is the most reliable way to limit spread during this window. Alcohol-based hand sanitizers are less effective against norovirus specifically. Cleaning contaminated surfaces matters too, since the virus can survive on countertops and doorknobs for days.
Dehydration Is the Real Danger
The stomach flu itself is rarely dangerous for otherwise healthy adults. The real risk is dehydration from losing fluids through vomiting and diarrhea faster than you can replace them. Young children, older adults, and people with weakened immune systems are most vulnerable.
In adults, signs of dehydration include extreme thirst, dark-colored urine, urinating less than usual, dry mouth, sunken eyes, feeling lightheaded or faint, and unusual fatigue. A simple skin check can also help: if you pinch the skin on the back of your hand and it doesn’t flatten back right away, you may be significantly dehydrated.
In infants and young children, watch for no wet diapers for three hours or more, no tears when crying, a dry mouth, sunken eyes, and unusual sleepiness or fussiness. These signs in a small child warrant prompt medical attention because children dehydrate faster than adults.
Staying Hydrated During Recovery
Small, frequent sips work better than gulping large amounts of fluid, which can trigger more vomiting. Water, broth, and oral rehydration solutions are all good options. You can make a simple rehydration drink at home: mix 4 cups of water with half a teaspoon of table salt and 2 tablespoons of sugar. The salt and sugar help your intestines absorb the water more efficiently, which plain water alone doesn’t do as well.
Skip caffeinated drinks, alcohol, and anything highly sugary like undiluted fruit juice or soda. These can worsen diarrhea or pull more water into the intestines.
What to Eat (and What You Can Skip)
You may have heard of the BRAT diet (bananas, rice, applesauce, toast) as the go-to for stomach flu recovery. Current medical guidance doesn’t support restricting your diet this way. Research shows that following a limited diet doesn’t help treat viral gastroenteritis, and most experts no longer recommend it.
The better approach: once your appetite returns, go back to eating your normal diet, even if you still have some diarrhea. For children, parents should offer whatever the child usually eats as soon as they’re willing to eat again. Forcing yourself to fast or eat only bland foods can actually slow your recovery by depriving your body of the calories and nutrients it needs to heal.
Stomach Flu vs. Food Poisoning
People often confuse the two because the symptoms overlap heavily. The key differences are timing and duration. Food poisoning from bacterial contamination tends to come on faster (sometimes within hours of eating the culprit) and resolves more quickly, often within a day. Viral gastroenteritis generally lingers for about two days, sometimes longer, and spreads from person to person rather than from a specific food source.
If multiple people who ate the same meal all get sick around the same time, food poisoning is more likely. If symptoms appear a day or two after contact with a sick person, you’re probably dealing with a stomach virus.