Adenovirus infection: symptoms, spread and when to get advice

Adenoviruses are a group of viruses that cause a range of infections. UKHSA explains that because there are many different types, it is possible to be infected more than once in a lifetime. Adenovirus is most common in babies and young children, but people of any age can be affected.

UKHSA monitors weekly positivity for adenovirus alongside other respiratory viruses such as human metapneumovirus, parainfluenza and rhinovirus, and publishes figures on its data dashboard. Adenovirus is therefore not a rare or exotic infection: it is part of the background of everyday viral illness in the UK.

Because adenovirus can look like many other viral infections, the practical advice from UKHSA and the NHS focuses on managing symptoms and knowing the warning signs.

UKHSA describes the typical picture as a cold-like illness. The NHS lists the main symptoms of a cold as a blocked or runny nose, sneezing, a sore throat, a hoarse voice, a cough and feeling tired and unwell, and says they come on gradually over 2 to 3 days.

Adenovirus can also cause illnesses affecting other parts of the body. The picture depends on which part is infected.

UKHSA says adenovirus spreads easily in settings where people are in close contact, such as nurseries, schools, hospitals and care homes. It can spread through droplets in the air when an infected person coughs or sneezes, through close personal contact such as shaking hands, by touching contaminated surfaces and then touching the mouth, nose or eyes, through contact with an infected person's poo, for example during nappy changing, and, less commonly, through contaminated water in swimming pools or lakes.

Adenoviruses can survive on surfaces for a long time, which is why shared objects can become sources of infection. People can also continue to shed the virus after they recover, sometimes without symptoms, which UKHSA says is particularly common in those with weakened immune systems.

UKHSA says most adenovirus infections clear up on their own with rest and plenty of fluids. Paracetamol can help if fever is causing discomfort, and a humidifier or saltwater nose drops may ease congestion. The NHS adds that for colds you can usually treat symptoms at home, that antibiotics are not recommended because colds are caused by viruses, and that nasal sprays should not be used for more than a week.

For diarrhoea and vomiting, the NHS says the most important thing is to have lots of fluids to avoid dehydration, that diarrhoea usually stops within 5 to 7 days and vomiting within 1 or 2 days, and that you should stay off school or work until you have not been sick or had diarrhoea for at least 2 days.

For conjunctivitis, the NHS suggests cleaning the eyelids with cooled boiled water, using a cold flannel, not wearing contact lenses until the eyes are better and not sharing towels or pillows.

UKHSA advises contacting a doctor if you or someone you care for has a high fever or one that lasts more than a few days, is having difficulty breathing, is under 3 months old or has a weakened immune system, has red eyes, eye pain or changes to vision, or has severe diarrhoea, vomiting or signs of dehydration.

The NHS adds specific thresholds for tummy bugs: call 111 if you are worried about a baby under 12 months, if a child under 5 has signs of dehydration, or if diarrhoea lasts more than 7 days or vomiting more than 2 days. Call 999 or go to A&E for vomiting blood, a stiff neck with pain from bright lights, severe breathing difficulty, or if someone is confused or not responding as usual.

For a cold, the NHS says to see a GP if a high temperature lasts more than 3 days, if symptoms get worse or do not improve after 10 days, or if you are short of breath or have chest pain.

UKHSA says good hygiene is the best defence: keep shared surfaces and objects clean using a bleach solution, stay at home when you have symptoms, wash hands frequently and thoroughly with soap and water, and cough and sneeze into your elbow or a tissue.

The NHS notes that colds are spread by germs from coughs and sneezes that can live on hands and surfaces for 24 hours, and that you are infectious until symptoms have gone.

On the NHS, mild adenovirus illness is managed at home with advice from a pharmacist, NHS 111 or a GP. Severe cases, particularly in very young babies, older people or those with weakened immune systems, may need hospital treatment.

Private GP or urgent care appointments can offer faster access, but there is no specific treatment that differs between sectors for a mild infection. If a child is struggling to breathe or a person seems very unwell, use NHS 111, 999 or A&E rather than waiting for a private appointment.