Most stomach bugs last 1 to 3 days. The vomiting typically stops within a day or two, while diarrhea can linger a bit longer. The total timeline depends on which virus you caught, your age, and your overall health, but the vast majority of people feel significantly better within 72 hours.
Timeline by Type of Virus
Norovirus is the most common stomach bug in adults and older children. Symptoms, mainly vomiting, diarrhea, and stomach cramps, begin 12 to 48 hours after exposure and typically resolve within 1 to 3 days. It hits fast and hard, but it also passes quickly. Most people feel the worst during the first 24 hours.
Rotavirus is the leading cause of stomach bugs in infants and young children. It tends to last longer than norovirus, with symptoms running 3 to 8 days. Young children are more vulnerable to dehydration during this stretch, which is why rotavirus vaccination is part of the standard infant immunization schedule.
Astrovirus, a less common cause, produces milder symptoms that last 1 to 4 days. It’s most frequent in young children and older adults but rarely causes severe illness.
What the First Few Days Look Like
The pattern is fairly predictable. After the incubation period of 12 to 48 hours (when you’ve been exposed but don’t feel sick yet), symptoms hit suddenly. Vomiting usually comes first, sometimes within hours of the first wave of nausea. Diarrhea, stomach pain, and low-grade fever follow. Some people also get body aches and chills that feel flu-like, though stomach bugs have nothing to do with influenza.
Day one is almost always the worst. Vomiting tends to taper off by day two for most adults. Diarrhea often hangs around a day or two longer than the vomiting does. By day three or four, most people are eating light meals again, though your appetite may take another day or two to fully return. Feeling tired and a little washed out for several days after the worst symptoms pass is completely normal.
How Long You Stay Contagious
This is where people get caught off guard. You remain contagious well after you feel better. With norovirus, you can still spread the virus for 2 weeks or more after your symptoms stop. The CDC recommends staying home for at least 48 hours after your last episode of vomiting or diarrhea. That means if your vomiting stops on a Tuesday morning, Wednesday morning is not yet safe. Thursday morning is the earliest you should return to work or school.
For children, the CDC’s school guidelines are slightly more specific: 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 the child isn’t having accidents and is having no more than two extra bowel movements above their normal in a 24-hour period.
Stomach Bug vs. Food Poisoning
People often use “stomach bug” and “food poisoning” interchangeably, but the timeline differs. A viral stomach bug follows the pattern above: 12 to 48 hours of incubation, then 1 to 3 days of symptoms. Bacterial food poisoning from contaminated food can start faster (sometimes within 6 hours) and, depending on the bacteria involved, may last longer or shorter.
One practical distinction: antibiotics do not help with a stomach bug. Stomach bugs are caused by viruses, and antibiotics only work against bacteria. Taking them won’t shorten your illness and may actually irritate your gut further.
Signs Your Stomach Bug Needs Medical Attention
Dehydration is the main risk with any stomach bug, especially for young children and older adults. If you can’t keep liquids down for 24 hours, or if vomiting and diarrhea have continued for more than two days without improvement, it’s time to call a doctor. Other red flags include bloody diarrhea, a fever above 104°F, and signs of severe dehydration like dizziness when standing, very dark urine, or no urination for many hours.
In infants, watch for fewer wet diapers than usual, crying without tears, and unusual sleepiness or irritability. Young children can dehydrate faster than adults because of their smaller body size.
When Your Gut Still Feels Off Weeks Later
Some people notice that their digestion doesn’t bounce back to normal even after the virus is long gone. Loose stools, bloating, cramping after meals, and sensitivity to foods you used to tolerate fine (especially dairy and fatty foods) can persist for weeks. This is usually temporary and happens because the infection disrupted the lining of your intestines, which needs time to heal.
In a smaller number of people, a stomach bug can trigger a longer-lasting condition called post-infectious irritable bowel syndrome. This involves ongoing cramping, irregular bowel habits, and digestive discomfort that can last for months or even years. About half of these cases resolve on their own within six to eight years, though many improve much sooner. If your symptoms are still disrupting your daily life a month after the original illness, it’s worth bringing up with your doctor rather than assuming it will sort itself out.