Vomiting from norovirus typically lasts 1 to 3 days, with the most intense episodes concentrated in the first 12 to 24 hours. The overall illness, including diarrhea and fatigue, usually resolves within 1 to 3 days as well, though some people feel wiped out for a few days beyond that. Symptoms appear 12 to 48 hours after exposure, and the vomiting often hits suddenly and forcefully.
What the First 24 Hours Look Like
Norovirus vomiting tends to come on fast. Many people go from feeling fine to vomiting within just a few hours. The first 12 to 24 hours are usually the worst, with repeated episodes that can feel relentless. Diarrhea, stomach cramps, and sometimes a low-grade fever often accompany the vomiting during this window.
By the second day, vomiting usually slows significantly or stops entirely. Diarrhea may linger a bit longer than the vomiting does, sometimes persisting for another day or two. Most healthy adults and older children are through the worst of it within 48 hours of the first symptom, though feeling drained and having a reduced appetite can hang on for several more days.
Why Norovirus Triggers Such Intense Vomiting
Norovirus infects the lining of your gut and activates specialized sensory cells called enterochromaffin cells. These cells flood the area with serotonin, which in this context acts as an alarm signal rather than a mood chemical. That serotonin stimulates the vagus nerve, which runs from your gut to your brainstem. Your brainstem then fires off signals that trigger the physical act of vomiting: a coordinated reflex involving your stomach muscles, diaphragm, and abdominal wall.
This is why norovirus vomiting feels so forceful and involuntary. It’s a hardwired nerve reflex, not just your stomach being irritated. The virus essentially hijacks a signaling pathway designed to expel threats from your digestive tract.
Staying Hydrated While You Can’t Keep Anything Down
Dehydration is the main risk with norovirus, especially for young children and older adults. The challenge is that drinking a full glass of water during active vomiting often just comes right back up. The most effective approach is to take very small sips: about a teaspoon (5 mL) of fluid every 5 minutes, gradually increasing the amount as your stomach tolerates it.
Oral rehydration solutions (available at any pharmacy) work better than plain water because they replace the salts and sugars your body loses. For children under about 22 pounds, aim for 2 to 4 ounces after each vomiting episode or bout of diarrhea. For larger children and adults, 4 to 8 ounces per episode is a reasonable target. If you don’t have a rehydration solution on hand, diluted juice or broth can bridge the gap.
Signs that dehydration has become serious include producing little or no urine, a rapid heartbeat, confusion, fainting, or rapid breathing. These warrant immediate medical attention.
How Long You Stay Contagious
Even after vomiting stops, you remain contagious. People with norovirus shed the virus in their stool for days and sometimes weeks after they feel better. The highest risk of spreading it to others is during the illness itself and for at least 48 hours after symptoms resolve. Thorough handwashing with soap and water (not just hand sanitizer, which doesn’t kill norovirus effectively) is critical during this window. Contaminated surfaces should be cleaned with a bleach-based solution.
When Symptoms Last Longer Than Expected
If vomiting continues beyond 3 days, something else may be going on, or dehydration may be compounding the problem. Young children, elderly adults, and people with weakened immune systems sometimes experience a longer and more severe course. In immunocompromised individuals, norovirus can persist for weeks or even months.
For most healthy people, though, the pattern is predictable: a miserable 1 to 2 days of vomiting, possibly another day of diarrhea, and then a gradual return to normal eating over the next few days. You don’t need to force full meals right away. Bland, easy-to-digest foods like crackers, rice, and bananas are easier on a recovering stomach.
Can You Get Norovirus Again?
Yes, but not immediately. After an infection, your body builds some immunity that lasts an estimated 4 to 9 years, according to modeling research from the CDC. However, there are many different strains of norovirus, and immunity to one strain doesn’t necessarily protect you from all others. This is why some people seem to catch “stomach bugs” repeatedly over their lifetime. Each time, the vomiting phase follows the same general pattern: sudden onset, intense for 12 to 24 hours, and largely over within a couple of days.