How Long Does a Stomach Bug Last?

Most stomach bugs are over within a few days, but the exact number depends on which virus you caught. The NIDDK publishes a different course for each of the four common ones — norovirus is the shortest at 1 to 3 days, adenovirus the longest at 1 to 2 weeks. Symptoms should improve day over day; that direction matters more than the total.

Duration by virus

Virus	Symptoms start after exposure	Symptoms last
Norovirus	12 to 48 hours	1 to 3 days
Rotavirus	about 2 days	3 to 8 days
Adenovirus	3 to 10 days	1 to 2 weeks
Astrovirus	4 to 5 days	1 to 4 days

These are the figures the NIDDK publishes. MedlinePlus, which does not split by virus, gives a broader “symptoms most often appear within 4 to 48 hours after contact” and says the illness goes away in a few days for most people without treatment.

You usually won’t know which virus you have, because testing isn’t routine for an otherwise healthy person. The practical read: if you’re past a week and still going, you’re outside the common pattern for the two most likely culprits.

Vomiting stops first, diarrhea lingers

The two halves of a stomach bug don’t end together. Vomiting is typically the most violent part and the shortest, often settling within a day. Loose stools continue after that, sometimes for several more days, and the last of them can trail past the point where you feel basically well.

That gap is normal and does not mean the infection has come back. What it does mean is that fluid losses are still happening — the reason rehydration continues after you feel better. See stomach bug symptoms for what to drink.

Kids, toddlers and older adults run longer

Rotavirus, the classic virus of early childhood, is already the second-longest of the four at 3 to 8 days, and young children tend to sit at the upper end of any range. Add that appetite and normal stools take extra days to return, and a toddler’s illness can feel like it lasted two weeks even when the infection itself was ordinary.

The NIDDK’s advice is not to stretch it out with a restricted diet: give children what they usually eat as soon as their appetite returns, and infants breast milk or formula as usual. For the infant picture specifically, see stomach bug in babies.

How long you stay contagious

Longer than you’re sick. Virus continues to shed in stool after symptoms end, for days in most people and longer in some. That is the real reason a household passes it around for two weeks: it isn’t reinfection, it’s the tail of the last person’s illness. Soap and water beat hand sanitizer here, and it’s worth keeping up well after the last symptom.

When the calendar itself is the warning sign

Seek care if diarrhea lasts more than several days, if there’s blood in the stool, if a fever returns after breaking, if you go 8 hours or more without urinating, or if symptoms worsen instead of easing. A prolonged course can mean a bacterial or parasitic infection rather than a virus, and that changes the treatment. See also diarrhea and vomiting causes and viral infection symptoms.

This content is informational and does not replace medical evaluation, diagnosis, or treatment.