Most cases of gastro (viral gastroenteritis) last 1 to 3 days, though some infections can stretch to 8 days depending on the cause. The worst symptoms typically hit within the first 24 to 48 hours, then gradually ease. Here’s what to expect from start to finish.
Timeline by Type of Infection
Viral infections are the most common cause of gastro. Norovirus, the single biggest culprit in adults, usually resolves within 1 to 3 days. Rotavirus, which more commonly affects young children, tends to last longer: vomiting and watery diarrhea can persist for 3 to 8 days.
Bacterial gastro from organisms like Campylobacter or Salmonella typically lasts 3 to 6 days, though it can occasionally drag on longer. Parasitic infections are the least common cause but tend to be the most stubborn, sometimes lasting weeks without treatment.
From Exposure to First Symptoms
After you’re exposed to the virus, there’s a gap before symptoms appear. For norovirus, this incubation period is 12 to 48 hours. The illness often starts abruptly: you might feel fine in the morning and be vomiting by evening. Other viruses and bacterial causes generally take 1 to 3 days to show up.
Symptoms tend to peak in intensity during the first day or two. Vomiting usually stops before diarrhea does. Many people find the vomiting phase lasts roughly 12 to 24 hours, while loose stools can linger for several more days even as you start to feel better overall.
How Long You’re Contagious
This is the part that surprises most people. Even after you feel fine, you can still spread norovirus for 2 weeks or more. The highest risk of transmission is during the acute illness and the first few days after symptoms stop, but viral shedding continues well beyond that.
For practical purposes, the CDC’s guidance for schools says children can return once vomiting has resolved overnight and they can hold down food and liquids in the morning. Diarrhea should have improved to no more than two extra bowel movements above normal in a 24-hour period. Thorough handwashing during the weeks after recovery is important, since alcohol-based hand sanitizers are not very effective against norovirus.
Dehydration: The Main Risk
Gastro itself is rarely dangerous. Dehydration is the real concern, especially in young children, older adults, and anyone who can’t keep fluids down. In adults, watch for extreme thirst, dark urine, dizziness, confusion, or skin that stays pinched when you pull it up. In infants and toddlers, the warning signs include no wet diapers for three hours, no tears when crying, a sunken soft spot on the skull, and unusual crankiness or sleepiness.
Mild to moderate dehydration can be managed at home by sipping small amounts of fluid frequently. Water, diluted juice, broth, and oral rehydration solutions all work. Drinking too much too fast can trigger more vomiting, so small, frequent sips are better than large gulps. Seek medical care if you or your child can’t keep any fluids down, if there’s blood in the stool, or if a fever reaches 102°F (39°C) or higher.
What to Eat During Recovery
You may have heard you should stick to bland foods like toast, bananas, and rice. Research actually shows that following a restricted diet doesn’t help treat gastro. The current recommendation from the National Institute of Diabetes and Digestive and Kidney Diseases is straightforward: go back to eating your normal diet as soon as your appetite returns, even if you still have some diarrhea. For infants, continue breast milk or formula as usual.
The priority is replacing fluids and electrolytes. Solid food can wait until you feel ready for it, but there’s no medical reason to limit yourself to a special diet once hunger returns.
Lingering Gut Symptoms After Recovery
Most people bounce back completely within a week. But a subset of people develop ongoing digestive issues after the infection clears. Studies estimate that anywhere from 3% to 36% of people who have a bout of infectious gastro go on to develop what’s called post-infectious irritable bowel syndrome. Symptoms include bloating, cramping, and altered bowel habits that can persist for months.
The wide range in that estimate depends on the specific bug involved. Dual infections and certain bacterial strains carry a higher risk. If your digestion still feels “off” weeks after the acute illness has passed, it’s worth flagging with a doctor. This is a recognized condition, not something you’re imagining, and it’s treatable.