Most stomach bugs last one to three days. The worst symptoms, vomiting and watery diarrhea, typically peak within the first 24 hours and then gradually taper off. By day two or three, most people are noticeably better, though fatigue and a touchy stomach can linger a bit longer.
Typical Timeline by Cause
The term “stomach bug” covers several different infections, and the exact duration depends on what’s causing it. Norovirus, the most common culprit in adults, tends to run its course in about one to two days. You feel terrible fast, but it passes fast too. Rotavirus, which hits young children hardest, lasts longer: vomiting and watery diarrhea can persist for three to eight days after symptoms appear, which is usually about two days after exposure.
Bacterial stomach bugs from contaminated food (Salmonella, Campylobacter, certain strains of E. coli) follow a slightly different pattern. Some resolve in a day or two without treatment, while others can stretch to a week or more depending on the specific bacteria and your overall health. If you need antibiotics, you should feel better within two to three days of starting them.
Food poisoning from bacterial toxins (as opposed to a live infection) tends to be the briefest. It hits hard, sometimes within hours of eating contaminated food, but often clears in less than a day because your body is reacting to the toxin rather than fighting a replicating pathogen.
What Each Day Looks Like
Day one is usually the roughest. Vomiting, diarrhea, nausea, and cramping come on suddenly and can feel relentless. Many people also develop a low-grade fever, chills, and body aches that mimic the flu. During this phase, keeping anything down can feel impossible, and dehydration is the main risk.
By day two, vomiting usually slows or stops, though diarrhea often hangs around longer. Your appetite starts to return in small waves. This is when most people begin tolerating small sips of water, diluted juice, or broth without it coming right back up. Plain, bland foods like toast, rice, or bananas are generally the easiest to reintroduce.
Day three and beyond is recovery territory for most viral stomach bugs. Diarrhea may still be loose, and your energy levels can stay low for another day or two, but the acute misery is behind you. Some people notice their digestion doesn’t feel fully normal for a week, which is common and not a sign of a new problem.
How Long You Stay Contagious
Here’s the part most people don’t realize: you remain contagious well after you feel better. With norovirus, the virus can stay in your stool for two weeks or more after recovery, even though you feel fine. People with rotavirus are contagious before symptoms even start and can spread the virus for up to two weeks after they’ve recovered.
This is why stomach bugs tear through households, daycare centers, and cruise ships so efficiently. Thorough handwashing with soap and water (not just hand sanitizer, which is less effective against norovirus) is the single most important thing you can do to avoid passing it on. Cleaning contaminated surfaces matters too, since the virus can survive on countertops and doorknobs for days.
Dehydration Is the Real Danger
The stomach bug itself is rarely dangerous for healthy adults. What makes people end up in urgent care is dehydration from losing fluids faster than they can replace them. Young children, older adults, and people with weakened immune systems are most vulnerable.
Signs of dehydration to watch for include dark yellow urine, dizziness when standing, a dry mouth, and producing very little urine. For small children, fewer wet diapers than normal, crying without tears, or unusual drowsiness are warning signs. The goal during the worst of the illness isn’t to eat. It’s to take frequent, tiny sips of fluid, even just a teaspoon at a time, to stay ahead of what you’re losing.
When It’s Lasting Too Long
A stomach bug that drags on past the normal window deserves attention. Diarrhea lasting more than seven days, or vomiting that continues beyond two days, falls outside the expected range for a typical viral infection. Symptoms persisting beyond five days in general are considered a red flag worth investigating.
Other signs that something more than a routine stomach bug may be going on include blood in your stool or vomit, a high fever (above 101.3°F or 38.5°C), severe abdominal pain that doesn’t come and go with cramping, and signs of significant dehydration that aren’t improving with oral fluids. These can point to a bacterial infection that needs treatment, a parasitic infection like Giardia (which is notorious for lasting weeks), or another condition entirely.
For most people, though, a stomach bug is a miserable but mercifully short experience. Two or three bad days, another day or two of feeling washed out, and then it’s behind you.