In brief
- With adenovirus infection, a temperature above 38 °C (100.4 °F) can last up to 5–7 days [1].
- A respiratory viral infection without bacterial complications usually clears up within 10 days, but a runny nose and cough may linger for another 1–2 weeks [1].
- A sick person sheds the most virus on day 3 after infection, and smaller amounts for up to 2 weeks [1].
- If the fever lasts more than 3 days, the child should see a doctor again [1].
Incubation times are from the clinical guidelines for adults [2]; everything else is from the guidelines for children [1].
Incubation period
The incubation period of acute respiratory viral infection (ARVI) is 1 to 14 days, and 1 to 5 days for the most common viruses [2].
For the eye form, epidemic keratoconjunctivitis, symptoms usually appear within 14 days after exposure [3]. An ophthalmologist on the eye form:
“The incubation period is five to seven days on average, although it can range from three to ten days. A typical feature is that the eyes are affected one after the other, two to three days apart, which helps in the differential diagnosis.”
AiF Voronezh, sponsored content (in Russian), January 28, 2026
How long the fever lasts
In 82% of patients with a respiratory viral infection, the fever goes down by day 2–3 of illness. A high fever lasts longer, up to 5–7 days, with flu and adenovirus infection [1].
“Adenovirus infection has a particular feature: the illness can come in two waves. After two to five days of normal temperature, the child starts to feel well, but then a high fever comes back. The sick person must see a doctor to decide whether hospital care is needed, because a very high fever and intoxication of the body can cause seizures”
AiF Komi (in Russian), November 1, 2023
A persistent temperature of 38 °C (100.4 °F) or higher for more than 3 days is typical of pneumonia; in respiratory viral infections this happens in only 18% of patients, more often with flu, adenovirus and enterovirus infections [1]. That is why a fever lasting more than 3 days calls for another visit to the doctor [1].
When the runny nose and cough go away
In most cases, a respiratory viral infection clears up within 10 days [1]. Without bacterial complications the illness is usually short, but nasal discharge and cough may linger for another 1–2 weeks [1].
In adults, the acute illness lasts 5–10 days; 11–30 days is called subacute, and more than 30 days, prolonged [2].
How long a person is contagious
Virus shedding peaks on day 3 after infection and drops quickly by day 5, but low-level shedding can continue for up to 2 weeks [1]. After recovery, the virus is sometimes shed for a long time, especially in people with weakened immune systems. There are no symptoms, but the person can still infect others [4]. More in how contagious adenovirus is.
When not to wait
See a doctor if your child has [1]:
- a temperature above 38.4–38.5 °C (101.1–101.3 °F) for more than 3 days;
- a stuffy nose that doesn't clear up in 10–14 days, especially if the fever has come back;
- a cough that lasts more than 10–14 days.
A high fever lasting more than 4–5 days that doesn't come down with fever reducers is a reason to admit the child to the hospital [1].
Frequently asked questions
What is the incubation period for adenovirus?
The incubation period of respiratory viral infections is 1 to 14 days, and 1 to 5 days for the most common viruses [2].
How long does a fever last with adenovirus?
A temperature above 38 °C (100.4 °F) can last up to 5–7 days [1].
How long can a cough last after adenovirus?
Without bacterial complications, a runny nose and cough can linger for another 1–2 weeks [1].
How long is adenovirus contagious?
Virus shedding peaks on day 3 after infection, and low-level shedding can continue for up to 2 weeks [1].
Illness timeline
Move the slider to see what happens on each day of the illness.
Sources
- Russian Ministry of Health, Union of Pediatricians of Russia. Clinical guidelines “Acute respiratory viral infection (ARVI)”, children, ID 25_3, published in the guidelines database on September 2, 2026 (in Russian). Accessed October 8, 2026.
- Russian Ministry of Health. Clinical guidelines “Acute respiratory viral infections (ARVI) in adults”, ID 724_2, published in the guidelines database on August 4, 2025 (in Russian). Accessed October 9, 2026.
- CDC, MMWR. Adenovirus-Associated Epidemic Keratoconjunctivitis Outbreaks — Four States, 2008–2010. MMWR 2013;62(32):637–641. Accessed October 8, 2026.
- CDC (US Centers for Disease Control and Prevention). About Adenovirus. Updated December 16, 2025. Accessed October 7, 2026.
This article was prepared by our editorial team from official sources and does not replace a doctor’s advice. Found an error? Write to us.