Most cases of viral gastroenteritis last one to three days, though symptoms can occasionally persist for up to 14 days depending on which virus is responsible. The specific timeline varies quite a bit by pathogen, age, and overall health, so a “stomach bug” that clears in 48 hours for one person may drag on for a week or more in another.
Typical Duration by Virus Type
Norovirus is the most common cause of viral gastroenteritis in adults. Symptoms like vomiting, diarrhea, and stomach cramps begin 12 to 48 hours after exposure and typically resolve within one to three days. Most people feel significantly better by day two or three, though fatigue and mild stomach sensitivity can linger a bit longer.
Rotavirus tends to affect young children more than adults. It causes watery diarrhea and vomiting lasting three to eight days. Adults with healthy immune systems who catch rotavirus generally recover in a few days, but young children often have a rougher, longer course.
Adenovirus (specifically types 40 and 41, which target the gut) is the outlier. These strains cause a noticeably longer illness. Adenovirus type 41 produces diarrhea lasting an average of 12 days, while type 40 tends to hit harder at the start but resolves a bit sooner, around 9 days. If your stomach bug has been going on for over a week and you’re otherwise healthy, an enteric adenovirus is a possible explanation.
Day-by-Day: What to Expect
Symptoms generally appear one to three days after you’re infected. The first 12 to 24 hours are usually the worst, with frequent vomiting, watery diarrhea, and cramping. Many people also develop a low-grade fever and body aches during this window.
By day two or three, vomiting usually tapers off first. Diarrhea tends to be the last symptom to resolve, sometimes continuing a day or two after everything else has improved. You may also notice your appetite is slow to return and your energy level stays low for several days after the active illness ends. This post-illness fatigue is normal and doesn’t mean you’re still contagious or getting worse.
Why Some People Stay Sick Longer
Young children and older adults tend to have longer, more intense episodes. Their bodies are more vulnerable to fluid loss, and their immune systems may take longer to clear the virus. People with weakened immune systems from chronic illness or medication can experience symptoms that stretch well beyond the typical range.
Dehydration itself can also make you feel worse for longer. When vomiting and diarrhea are frequent, the resulting fluid and electrolyte loss causes dizziness, headaches, and deep fatigue that compound the illness. Staying on top of fluid replacement can make a real difference in how quickly you feel like yourself again.
Staying Hydrated During Recovery
The single most important thing you can do during a stomach bug is replace lost fluids. For adults and older children, take frequent small sips of water or an oral rehydration solution rather than gulping large amounts at once. If you vomit, wait about 10 minutes, then start sipping again more slowly. For younger children, offer 50 to 100 milliliters (a few tablespoons to half a cup) of fluid after each loose stool for kids under two, and 100 to 200 milliliters for children over two.
Signs that dehydration is becoming a problem include very dark urine, dry mouth, no tears when crying (in children), dizziness when standing, and significantly reduced urination. In infants, a sunken soft spot on the head is a red flag. Severe dehydration requires medical attention and sometimes IV fluids, particularly in very young children and older adults.
When You Can Go Back to Work or School
The CDC recommends staying home for a minimum of 48 hours after your last episode of vomiting or diarrhea. This isn’t just about feeling better. You continue shedding virus in your stool for days after symptoms stop, and the 48-hour window reduces the chance of spreading it to others. For food handlers, this 48-hour rule is especially strict, and some local regulations require an even longer exclusion period.
Even after that 48-hour mark, thorough handwashing remains critical. Norovirus in particular is highly contagious and can survive on surfaces for days. Alcohol-based hand sanitizers are less effective against it than soap and water.
Lingering Gut Symptoms After Recovery
About 1 in 10 people who recover from a gut infection go on to develop post-infectious irritable bowel syndrome, or PI-IBS. This means that even after the virus is completely gone, you may experience bloating, cramping, loose stools, or alternating constipation and diarrhea for weeks or months. The infection triggers changes in gut sensitivity and the balance of bacteria in your intestines that can take time to settle.
PI-IBS is not a new infection and doesn’t mean something was missed. It’s a recognized pattern that gradually improves for most people, though it can take several months. If your digestion still feels off a few weeks after a stomach bug, this is a likely explanation.