Bronchiolitis in Babies: Signs, Treatment, and When to Go to Hospital

Bronchiolitis is a viral infection of the smallest airways in the lungs (the bronchioles). It causes them to swell and fill with mucus, making it harder for babies to breathe and feed. It is the most common serious respiratory illness in babies and young children in the UK, affecting around one in three infants in their first year of life.

Most cases are mild and can be managed at home. However, in babies under three months, or those born prematurely, bronchiolitis can become serious quickly. Knowing what to watch for is essential.

What Causes Bronchiolitis

The majority of cases — around 80 per cent — are caused by respiratory syncytial virus (RSV). Other viruses, including rhinovirus and parainfluenza, can cause the same illness. Bronchiolitis season typically runs from October to March in the UK, peaking around December and January.

The virus spreads through respiratory droplets and contact with contaminated surfaces. It can survive on hands for 30 minutes and on hard surfaces for several hours, which is why it spreads so easily in households and childcare settings.

Who Is Most at Risk

Bronchiolitis affects almost all children by the age of two, but the most severe illness occurs in:

• Babies under six months, particularly those under three months
• Babies born prematurely (before 37 weeks gestation)
• Babies with underlying heart or lung conditions
• Babies who are immunocompromised
• Babies who were not breastfed (breastfeeding offers some protective immunity)

Symptoms to Recognise

Bronchiolitis typically begins like a common cold — runny nose, mild cough, and possibly a low-grade temperature. Over two to three days, it can develop into:

• A persistent, dry cough
• Fast or noisy breathing, with a wheeze on breathing out
• Difficulty feeding — taking longer than usual, stopping frequently, or refusing feeds altogether
• Flaring nostrils as the baby works harder to breathe
• The muscles below the ribs or between the ribs pulling in visibly with each breath (known as recession or intercostal indrawing)
• Unusual irritability or lethargy

Most children are most unwell between days three and five. Symptoms usually improve within two weeks, though the cough can persist for three to four weeks.

Home Treatment

There are no antiviral medicines for bronchiolitis, and antibiotics are not effective because it is a viral illness. Treatment focuses on supporting your baby while the illness runs its course.

What you can do at home

Keep feeding going. Maintaining hydration is the most important thing. If your baby is breastfed, offer more frequent, shorter feeds. If bottle-fed, offer smaller amounts more often. If your baby is struggling to drink enough, a small amount of expressed breast milk or formula via syringe can help.

Keep the nose clear. Saline nasal drops, available from pharmacies without prescription, can help loosen mucus and make feeding and breathing slightly easier. A nasal aspirator can help clear the nostrils before feeds.

Upright positioning. Holding your baby upright or semi-upright during feeds and for a period afterwards can help ease breathing slightly.

Paracetamol or ibuprofen can be used if your baby has a fever and is clearly uncomfortable — follow NHS dosing guidelines for age and weight. Do not give ibuprofen to babies under three months or those who are dehydrated.

Do not use over-the-counter cough and cold medicines in babies and children under six. They are not effective and some can be harmful.

Do not expose your baby to tobacco smoke, which significantly worsens breathing problems.

When to Go to Hospital

This is the most important part of any bronchiolitis guide. Contact your GP, call 111, or take your baby to A&E if you notice any of the following.

Call 999 or go straight to A&E if your baby:

• Has blue or grey lips, tongue, or fingernails (cyanosis)
• Is making a grunting noise with each breath
• Has very fast breathing with pauses
• Is floppy and difficult to rouse
• Has severe recession — the chest and stomach are visibly pulling in dramatically with every breath

Contact 111 or your GP urgently if:

• Your baby is under three months old and has any deterioration in breathing
• They are taking less than 50 per cent of their usual feed volume over 24 hours
• They have had no wet nappy for more than 12 hours
• You are worried and something does not seem right — trust your instincts

What Happens in Hospital

In hospital, treatment aims to support your baby while the immune system clears the virus. This may include:

• Oxygen therapy via a nasal cannula or face mask if oxygen saturation is low
• Nasogastric (NG) tube feeding if your baby cannot take enough milk by mouth — a fine tube passed through the nose into the stomach allows milk to be given safely without the baby having to suck
• Monitoring of heart rate, breathing rate, and oxygen levels
• High-flow nasal cannula (HFNC) oxygen in more severe cases, which delivers warm, humidified oxygen under gentle pressure to help keep the small airways open

Most babies admitted to hospital with bronchiolitis improve within two to five days and are discharged once they can maintain their own oxygen levels and take sufficient feeds.

Prevention

Good hand hygiene is the most effective prevention measure. Wash hands thoroughly before touching your baby, after nappy changes, and after coughing or blowing your nose. Ask others to do the same.

From the 2024/25 season, the UK introduced a national programme offering nirsevimab (Beyfortus) to eligible newborns and young infants, which provides protection against severe RSV-related bronchiolitis. Speak to your midwife or health visitor about eligibility.

Bronchiolitis is frightening for parents, but the vast majority of babies recover fully without any lasting effects. If you are ever unsure, seek advice — it is always better to be checked than to wait.