Most stomach bugs last one to three days, though symptoms can stretch to seven days or, in some cases, up to 14 days depending on the virus or bacteria involved. The wide range comes down to what’s causing the illness, your age, and your overall health.
Duration by Type of Infection
Norovirus, the most common cause of the stomach bug in adults, tends to be intense but short. Most people feel better within one to two days of symptoms starting. Rotavirus, which more commonly hits young children, lasts longer: vomiting and watery diarrhea typically continue for three to eight days. Symptoms for both viruses usually appear one to three days after exposure.
Bacterial infections generally stick around longer than viral ones. Shigella infections, for example, cause symptoms that last about seven days, though many people improve within five days without antibiotics. Salmonella and campylobacter follow a similar pattern, often running four to seven days before clearing on their own.
Viral gastroenteritis symptoms can range from mild to severe and, in unusual cases, persist up to 14 days. If you’re past the two-week mark and still feeling sick, something else may be going on.
What the Timeline Actually Looks Like
The first 12 to 24 hours are usually the worst. Vomiting tends to come on suddenly and may hit in waves, often tapering off within a day. Diarrhea typically follows and can outlast the vomiting by several days. You might feel wiped out, achy, and have a low-grade fever during this window.
By day two or three with a norovirus infection, most people notice a real turning point. Appetite starts creeping back, nausea fades, and energy slowly returns. With rotavirus or a bacterial bug, this improvement phase may not arrive until day four or five. Even after the worst passes, lingering fatigue and loose stools can hang around for a few more days. Some people have trouble digesting dairy for up to a month after recovering, so if milk or cheese seems to bother you in the weeks after a stomach bug, that’s a recognized aftereffect.
How Long You Stay Contagious
Here’s the part most people don’t realize: you remain contagious for two to three days after your symptoms end. You can spread the virus from the moment symptoms begin through several days after you feel fine again. This is why stomach bugs tear through households and offices so effectively.
Avoid close contact with others and skip travel until at least two to three days after your last symptoms. For children returning to school, the general guideline is that vomiting should have resolved overnight and the child should be able to hold down food and liquids in the morning. Diarrhea should have improved enough that bowel movements are no more than two above the child’s normal frequency in a 24-hour period.
Eating and Drinking During Recovery
Staying hydrated matters more than eating during the worst of it. Replace lost fluids and electrolytes with water, broth, or an oral rehydration solution. For infants and young children, continue breast milk or formula as usual and start offering extra fluids at the first sign of illness, before dehydration sets in.
Once your appetite returns, you can go back to your normal diet even if diarrhea hasn’t fully stopped. Research shows that following a restricted diet doesn’t actually help you recover faster from viral gastroenteritis, and most experts don’t recommend fasting through it. That said, a few things can make diarrhea worse while your gut is still irritated: caffeinated drinks, high-fat or fried foods, very sugary beverages, and dairy products. Easing back into those over the following days is reasonable.
Dehydration Warning Signs
Dehydration is the main complication of any stomach bug, and it develops faster than most people expect, especially in young children and older adults. In adults, watch for extreme thirst, dark yellow urine or very little urine output, dizziness, confusion, and fatigue. Skin that doesn’t flatten back right away after being gently pinched is another reliable sign.
In infants and young children, the signals look different: no wet diapers for three hours (or six hours in babies), no tears when crying, a dry mouth, sunken eyes, a sunken soft spot on top of the head, and unusual crankiness or sleepiness. These signs warrant a call to a pediatrician right away.
Signs That Something More Serious Is Happening
Most stomach bugs are miserable but not dangerous. There are specific situations, though, where the illness has either lasted too long or become severe enough to need medical attention.
For adults, those red flags include vomiting or diarrhea lasting more than two days, inability to keep liquids down for 24 hours, blood in vomit or stool, severe stomach pain, and a fever above 104°F. For children, the thresholds are lower: a fever of 102°F or higher, bloody diarrhea, signs of dehydration, or unusual lethargy or irritability. For babies specifically, frequent vomiting, no wet diaper in six hours, severe diarrhea, or a sunken soft spot all call for immediate medical attention.