In brief
- Most often adenovirus looks like a cold or the flu: fever and a sore throat [1].
- What sets it apart is that it affects not only the airways but also lymphoid tissue, the conjunctiva (the lining of the eye) and the gut [2].
- A high fever with adenovirus can last longer than with most respiratory viruses — up to 5–7 days [2].
- There is no specific antiviral treatment, and most cases are mild [3]. Treatment is decided by a doctor.
When to call emergency services
Clinical guidelines list danger signs that mean a child of any age should be admitted to the hospital [2]. Call your local emergency number (911 in the US, 999 in the UK, 112 in the EU) if your child:
- can't or won't drink or breastfeed;
- is drowsy, floppy, doesn't engage (won't make eye contact), is unconscious — or, the opposite, is extremely agitated;
- has trouble breathing: shortness of breath, fast breathing, the soft parts of the chest pulling in, grunting or moaning breaths, pauses in breathing;
- has bluish skin and lips (central cyanosis);
- shows signs of heart failure;
- is severely dehydrated;
- has a high fever lasting more than 4–5 days that doesn't come down with fever reducers;
- has bleeding: nosebleeds, streaks of blood when coughing, a rash of tiny bleeds under the skin.
Babies under 3 months with a high fever, and children with complex febrile seizures — lasting longer than 15 minutes or repeating within 24 hours — are also admitted to the hospital [2].
See a doctor if
- your child refuses to drink for a long time;
- their behavior has changed: irritability, unusual sleepiness, little response when you try to engage them;
- breathing is labored, noisy or fast, or the spaces between the ribs or the notch above the breastbone pull in;
- seizures or delirium appear with the fever;
- a fever above 38.4–38.5 °C (101.1–101.3 °F) lasts more than 3 days;
- a stuffy nose doesn't clear up in 10–14 days, especially if the fever comes back or your child gets worse;
- there is ear pain or discharge from the ear;
- a cough lasts more than 10–14 days.
“Adenovirus infection has a peculiarity. 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 hospitalization is needed, because a very high fever and intoxication of the body can cause seizures”
AiF Komi (in Russian), November 1, 2023
What the symptoms are
Adenoviruses cause a wide range of symptoms. Which ones depends on the virus type and where it multiplies: in the airways, on the lining of the eye or in the gut [1].
- like a cold or the flu
- fever
- sore throat
- acute bronchitis, pneumonia
- conjunctivitis (pink eye)
- nausea, vomiting, diarrhea
- acute gastroenteritis
Clinical guidelines specifically note that adenovirus infection can affect the digestive tract, with nausea, vomiting and diarrhea [2]. Less often, adenovirus causes bladder inflammation and neurological disease [1].
According to clinical guidelines, babies under 6 months are protected from adenovirus by their mother's antibodies. After that, a child may get it several times, gradually building immunity, and gets sick less often with age [2]. More about the eye form in our article on adenoviral conjunctivitis.
“Symptoms appear gradually — first fever, then conjunctivitis, then cough”
Izvestia (in Russian), May 24, 2023
How long it lasts
The timelines in clinical guidelines are given for respiratory viral infections in general, with a longer fever noted separately for adenovirus [2].
A sick person sheds the most virus on day 3 after infection; by day 5 shedding drops sharply, but small amounts may continue for up to 2 weeks [2]. If the fever lasts more than 3 days or your child gets worse, they need to see a doctor again [2].
How children catch it
- through close contact, such as shaking hands;
- through droplets from coughs and sneezes;
- through objects that carry the virus, if you then touch your face with unwashed hands;
- through stool, for example when changing a diaper;
- less often — through water in a poorly chlorinated swimming pool or lake [1].
Adenovirus is hardy outside the body: at room temperature it survives up to 2 weeks and withstands cold and drying, but it is killed by ultraviolet light and chlorine-based disinfectants. Outbreaks in daycare centers and schools are possible [2]. Russian clinical guidelines advise keeping a sick child at home rather than sending them to daycare or school [2].
“Parents of children under three should stay alert and see a doctor in time to prevent a severe course of the illness.”
Izvestia (in Russian), May 24, 2023
Who is at higher risk
The risk of severe illness is higher in people with weakened immune systems and in those with existing respiratory or heart conditions [1]. If your child has one of these conditions, see a doctor at the first symptoms.
How a doctor knows it's adenovirus
Usually adenovirus infection is recognized on examination. If confirmation is needed, clinical guidelines list a rapid test of a throat or nose swab and PCR of a nasopharyngeal swab [2].
Antibiotics don't work against viruses. For an uncomplicated respiratory viral infection — including one with conjunctivitis, laryngitis or bronchitis in the first 10–14 days of illness — clinical guidelines do not recommend them [2]. Treatment decisions are made by a doctor.
“PCR testing is fast and informative: you get the result in two days at most. If you see, say, a rhinovirus or an adenovirus, you understand that you need to wait it out.”
Sib.fm / AiF Novosibirsk (in Russian), October 1, 2026
This article was checked against the current edition of the Russian Ministry of Health clinical guidelines on acute respiratory viral infections in children, published in the guidelines registry on September 2, 2026.
Frequently asked questions
How is adenovirus different from a common cold?
Besides the airways, it affects lymphoid tissue, the conjunctiva of the eyes and the gut, and a high fever can last up to 5–7 days [2].
How long does adenovirus fever last in a child?
With most respiratory viruses the fever breaks on day 2–3; with adenovirus it can last up to 5–7 days. If a fever above 38.4–38.5 °C (101.1–101.3 °F) lasts more than 3 days, the child should see a doctor again [2].
Can my child go to daycare with adenovirus?
No: Russian clinical guidelines advise keeping a sick child at home and not sending them to daycare or school [2].
Does a child with adenovirus need antibiotics?
Antibiotics don't work against viruses and are not recommended for an uncomplicated respiratory viral infection [2]. The decision is made by a doctor.
How the virus itself is built
Spin the virion model and take it apart piece by piece.
Sources
- CDC (US Centers for Disease Control and Prevention). About Adenovirus. Updated December 16, 2025. Accessed October 7, 2026.
- 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.
- CDC (US Centers for Disease Control and Prevention). Clinical Overview of Adenovirus. 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.