Most adenovirus infections last a few days to two weeks, though the exact timeline depends on which part of the body is affected. Respiratory infections tend to clear fastest, while digestive and eye infections can drag on longer. Here’s what to expect for each type, how long you’re contagious, and what a longer recovery looks like.
Incubation Period Before Symptoms Start
After exposure, adenovirus doesn’t cause symptoms right away. The gap between catching the virus and feeling sick varies by infection type: 2 to 14 days for respiratory infections, 3 to 10 days for stomach and intestinal infections, and 4 to 12 days for eye infections. During part of this window you can already spread the virus to others, even though you feel fine.
Respiratory Infections: A Few Days to Two Weeks
Adenovirus is one of many viruses that cause cold-like illness, sore throat, and cough. For most people, these symptoms resolve within a few days to two weeks. Fever typically breaks within the first five days. A lingering cough is common even after other symptoms have cleared and can stick around for an additional week or so.
A fever above 104°F (40°C), or one that persists beyond five days, is a signal that the infection may be more serious and warrants medical attention. In otherwise healthy adults and older children, though, respiratory adenovirus infections follow a predictable arc: a few rough days of fever and congestion, then a steady improvement.
Stomach and Intestinal Infections: Up to 12 Days
Certain adenovirus strains target the gut rather than the airways, causing vomiting and diarrhea. The diarrhea phase tends to outlast the vomiting and often runs 8 to 12 days, which is notably longer than many other stomach bugs like norovirus (which typically wraps up in 1 to 3 days). Most people recover completely without any specific treatment, but staying hydrated is especially important during that stretch because prolonged diarrhea increases the risk of dehydration, particularly in young children.
Eye Infections: 2 to 4 Weeks
Adenoviral conjunctivitis (pink eye) is the slowest to resolve. Expect red, watery, irritated eyes for 2 to 4 weeks. The infection clears on its own without antiviral treatment, but those weeks can be uncomfortable. Symptoms often start in one eye and spread to the other within a few days.
This form of adenovirus is also extremely contagious. You can spread it for 10 to 12 days from when redness first appears, plus there’s a contagious window of 3 to 7 days before visible symptoms even show up. Towels, pillowcases, and anything that touches the face are common transmission routes.
How Long You’re Contagious
Contagiousness outlasts symptoms by a wide margin with adenovirus, and this is one of the things that makes it spread so easily. Children with respiratory infections shed the virus in both throat secretions and stool for 3 to 6 weeks after becoming sick. That means a child who seems fully recovered can still pass the virus to others for weeks.
In rare cases, viral shedding can continue for 18 months or longer. This is uncommon but worth knowing about in settings like daycares or households with very young children or people with weakened immune systems.
The virus itself is remarkably tough outside the body. It survives on hard surfaces like countertops, doorknobs, and plastic toys for anywhere from 7 days to 3 months at room temperature. Regular cleaning of shared surfaces makes a real difference in limiting household spread.
Severe Cases and Pneumonia
Most adenovirus infections are mild, but the virus occasionally causes pneumonia, particularly in young children and people with weakened immune systems. When pneumonia develops, recovery is a different experience entirely. Surviving children recover gradually over several months, not days or weeks. Some develop lasting changes in lung function.
For people with compromised immune systems, such as organ transplant recipients or those undergoing chemotherapy, adenovirus poses a more serious threat. The virus can persist in the digestive tract and continue shedding without causing obvious gut symptoms, while still carrying the risk of spreading to the bloodstream. In one study of pediatric transplant patients, the virus appeared in the blood a median of 11 days after being detected at high levels in stool. These cases require close monitoring that goes well beyond what a typical infection demands.
Timeline Summary by Infection Type
- Respiratory (cold, sore throat, cough): A few days to 2 weeks. Fever typically under 5 days, cough may linger longer.
- Gastrointestinal (vomiting, diarrhea): Diarrhea commonly lasts 8 to 12 days.
- Conjunctivitis (pink eye): 2 to 4 weeks for full resolution.
- Pneumonia (severe cases): Months of gradual recovery.
- Contagious period: 3 to 6 weeks of viral shedding in children, potentially longer in some cases.
If you’re trying to figure out whether you or your child still has adenovirus versus something new, timing helps. A respiratory infection that stretches well past two weeks, or a fever that won’t break after five days, suggests either a complication or a different illness layered on top. Testing is most accurate when specimens are collected within the first week of symptoms.