Most stomach bugs last 1 to 3 days. The majority of cases are caused by norovirus, which typically brings on vomiting and diarrhea within 12 to 48 hours of exposure and clears up within 72 hours. Some viruses can stretch symptoms out longer, but the worst of it almost always passes within a week.
Timeline by Virus Type
Norovirus is the most common culprit behind what people call the “stomach bug” or “stomach flu.” Symptoms hit fast, usually starting 12 to 48 hours after you pick up the virus. The acute phase, with its intense vomiting and diarrhea, lasts 1 to 3 days for most healthy adults. By day three, the worst is typically over, though you may feel drained for another day or two.
Rotavirus tends to last longer, especially in young children. Vomiting and watery diarrhea can persist for 3 to 8 days. In adults with healthy immune systems, rotavirus is usually milder and resolves in a few days, partly because most adults have some immunity from childhood exposure.
Adenovirus is a less common cause of stomach illness but has the longest timeline. Symptoms can take 3 to 10 days to appear after exposure and then linger for 1 to 2 weeks. If your stomach bug seems to drag on well past a week without getting worse, adenovirus is one possible explanation.
What the First 72 Hours Look Like
The pattern for most stomach bugs follows a predictable arc. The first 12 to 24 hours are usually the roughest. Vomiting often comes first, sometimes hitting suddenly and intensely. Diarrhea follows within hours. You may also have stomach cramps, a low fever, muscle aches, and headache. Many people describe a deep, full-body fatigue that makes it hard to get off the couch.
By day two, vomiting usually starts tapering off. Diarrhea may continue a bit longer but becomes less frequent. Day three often feels like a turning point: you can keep fluids down, your appetite starts returning (even if food doesn’t sound great yet), and your energy slowly comes back. Some lingering loose stools or mild nausea can stick around for a day or two beyond that, which is normal.
How Long You Stay Contagious
This is where the timeline gets tricky, because you stay contagious well beyond when you feel better. With norovirus, you’re most contagious while you have symptoms, especially while vomiting. But you remain infectious for the first few days after symptoms resolve, and studies show you can continue shedding the virus for two weeks or more after you feel fine.
This is why workplace and institutional guidelines call for staying home at least 48 hours after your last symptoms. That window is especially important if you handle food or work with vulnerable populations like young children or elderly adults. Hand sanitizer won’t cut it either. Alcohol-based sanitizers don’t kill norovirus. Washing your hands with soap and warm water for at least 20 seconds is the only reliable way to remove the virus from your skin.
Stomach Bug vs. Food Poisoning
If your symptoms came on very quickly (within a few hours of eating something suspicious), you may be dealing with bacterial food poisoning rather than a viral stomach bug. Some types of bacterial food poisoning resolve much faster. Illness from certain bacteria that produce toxins in food, for instance, can cause intense cramps and diarrhea that clear up in less than 24 hours. Other bacterial infections, like salmonella, can last several days to a week and produce symptoms that overlap heavily with a viral stomach bug.
The key differences: bacterial food poisoning often hits faster (sometimes within 1 to 6 hours), may cause more severe cramping, and sometimes involves bloody diarrhea, which is uncommon with viral stomach bugs. If multiple people who ate the same meal get sick around the same time, food poisoning is the more likely explanation. If family members get sick one after another over several days, a virus is spreading through the household.
Staying Hydrated Is the Main Treatment
There’s no medication that shortens a viral stomach bug. Your immune system clears the infection on its own. The real risk during those 1 to 3 days is dehydration, especially for young children, older adults, and anyone who can’t keep fluids down. Small, frequent sips of water, clear broth, or an oral rehydration solution work better than trying to gulp down a full glass at once. If you can manage only a tablespoon every few minutes, that still counts.
Once vomiting settles, plain foods like crackers, rice, bananas, and toast are easy starting points. There’s no need to follow a strict diet, though. Eat what you can tolerate and build back up gradually. Avoid dairy, caffeine, alcohol, and fatty or heavily spiced foods until your stomach feels fully settled.
Signs That Something More Serious Is Happening
Most stomach bugs resolve without any medical care. But certain symptoms signal that your body isn’t coping well, particularly if dehydration sets in. For adults, the red flags include being unable to keep any liquids down for 24 hours, vomiting or diarrhea lasting more than two days, vomiting blood, blood in your stool, severe stomach pain, or a fever above 104°F. Signs of dehydration to watch for include very dark urine, producing little or no urine, extreme thirst, dry mouth, and dizziness or lightheadedness.
Children and infants dehydrate faster than adults, so the threshold for concern is lower. In infants, watch for no wet diaper in six hours, a sunken soft spot on the head, crying without tears, or frequent vomiting. In older children, a fever of 102°F or higher, bloody diarrhea, unusual tiredness or irritability, or signs of dehydration all warrant a call to their doctor. The younger the child, the faster dehydration can become dangerous.
Preventing It From Spreading at Home
If one person in your household has a stomach bug, the virus is almost certainly on surfaces already. Norovirus is remarkably hardy. It survives on countertops, door handles, and bathroom fixtures for days. Clean any surface that may have been contaminated with a bleach solution: one cup of regular bleach per gallon of water. Let the surface stay wet for at least one minute before wiping it dry. Standard household cleaners and disinfecting wipes aren’t reliably effective against norovirus.
Wash contaminated clothing and bedding on the hottest setting your machine offers. Keep the sick person’s towels, cups, and utensils separate. And keep washing your hands, especially after any contact with the sick person, their bathroom, or their laundry. The virus spreads through microscopic amounts of stool and vomit, so even surfaces that look clean can carry enough virus to infect someone.