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🩺 Medically reviewed by the Health Decoded Guide Editorial Team· Last reviewed: August 2026
🔍 Quick Summary
Bronchiolitis is a common viral chest infection that mainly affects babies and children under 2 years of age. It causes inflammation and mucus buildup in the small airways of the lungs, making breathing more difficult.
Most children recover with supportive care at home, but some babies—especially very young infants—may need hospital treatment.
1️⃣ Introduction
Bronchiolitis is an infection of the tiny airways (bronchioles) inside the lungs. It is most commonly caused by the respiratory syncytial virus (RSV), although other viruses can also cause it.
The condition is most common during the colder months and usually affects babies younger than 2 years, particularly those under 12 months.
• mainly affects babies and toddlers
• caused by viruses, not bacteria
• spreads easily through coughs, sneezes and contaminated surfaces
👉 Bronchiolitis is different from bronchitis and is one of the most common reasons young babies are admitted to hospital during winter.
2️⃣ How it happens
After entering the body through the nose or mouth:
• the virus infects the small breathing tubes (bronchioles)
• the airways become swollen and irritated
• thick mucus builds up inside the airways
• the narrowed airways make it harder for air to move in and out of the lungs
Young babies have very small airways, so even a small amount of swelling can make breathing difficult.
👉 The breathing difficulty is caused by swollen airways and mucus—not because the lungs stop working.
3️⃣ Who is at higher risk?
Bronchiolitis can affect any baby, but the risk of severe illness is higher in:
• babies younger than 6 months
• premature babies
• babies with heart disease
• babies with chronic lung disease
• babies with weakened immune systems
• babies exposed to cigarette smoke
👉 Younger babies have smaller airways and less reserve, making them more likely to become unwell.
4️⃣ Common causes
The most common cause is:
Respiratory Syncytial Virus (RSV)
Other viruses include:
• rhinovirus
• influenza virus
• parainfluenza virus
• human metapneumovirus
• adenovirus
The infection spreads through:
• coughing and sneezing
• direct contact with infected people
• touching contaminated toys, surfaces or hands
5️⃣ Symptom explanation
Bronchiolitis often starts like an ordinary cold before affecting the lungs.
Symptoms may include:
• blocked or runny nose
• cough
• mild fever
• wheezing
• fast breathing
• noisy breathing
• difficulty feeding
• reduced appetite
Symptoms usually become worse around days 3 to 5 before gradually improving.
👉 Babies often feed poorly because it is difficult to breathe and suck at the same time.
6️⃣ Associated symptoms
Some babies may also develop:
• tiredness
• irritability
• vomiting after coughing
• fewer wet nappies due to dehydration
• pauses in breathing (apnoea), especially in young infants
👉 Very young babies may not cough much but can become sleepy, feed poorly or stop breathing for short periods.
7️⃣ When it becomes dangerous 🚨
Seek urgent medical care immediately if your baby:
• is struggling to breathe
• has chest recession (skin pulling in between the ribs or below the ribs)
• is breathing very fast
• develops blue lips or tongue
• has repeated pauses in breathing
• is difficult to wake
• is feeding much less than usual
• has significantly fewer wet nappies
👉 These may indicate:
• severe bronchiolitis
• dehydration
• low oxygen levels requiring hospital treatment
8️⃣ Management and treatment
Bronchiolitis is caused by a virus, so antibiotics are usually not helpful.
Treatment focuses on supporting your baby while the infection improves.
This may include:
• offering smaller, more frequent feeds
• encouraging fluids to prevent dehydration
• gently clearing the nose with saline drops if recommended
• keeping your child comfortable
• monitoring breathing and feeding
Some babies admitted to hospital may need:
• oxygen therapy
• feeding through a tube if unable to feed
• intravenous fluids if severely dehydrated
👉 Most children begin to improve within 7–10 days, although the cough may last longer.
9️⃣ Diagnosis
Doctors usually diagnose bronchiolitis by:
• asking about symptoms
• examining your baby's breathing
• checking oxygen levels with a pulse oximeter
Most children do not need:
• blood tests
• chest X-rays
• routine viral testing
👉 The diagnosis is usually based on your child's age, symptoms and physical examination.
🟢 Important Message
Bronchiolitis is a common viral infection in babies and young children. While most children recover with supportive care at home, parents should know the warning signs that require urgent medical attention.
👉 If your baby's breathing becomes difficult or feeding drops significantly, seek medical care promptly.
FAQ
• Is bronchiolitis contagious?
Yes. The viruses that cause bronchiolitis spread easily from person to person.
• Can antibiotics treat bronchiolitis?
No. Bronchiolitis is usually caused by viruses, so antibiotics are not effective unless there is a bacterial infection.
• How long does bronchiolitis last?
Symptoms often peak around days 3–5 and gradually improve over 1–2 weeks, although the cough may last longer.
• Can a child get bronchiolitis more than once?
Yes. Different viruses can cause bronchiolitis, and immunity is not permanent.
• Can bronchiolitis lead to asthma?
Some children develop recurrent wheezing after bronchiolitis, but not all go on to develop asthma.
🧠 Why We Delay
Many parents think bronchiolitis is simply a bad cold because it often begins with a runny nose and cough. However, babies can become unwell quickly as swelling and mucus block their tiny airways.
Young babies may not always appear severely ill at first, so changes in breathing, feeding and alertness should never be ignored.
👉 In bronchiolitis, watching how your baby breathes is often more important than watching the fever.
🔗 Related Health Topics
• Ear infection
• Wheezing in Children
• Asthma in Children
• Asthma Action Plan
• Fever in Children
📚 Medical References
• National Health Service (NHS). Bronchiolitis.
• Centers for Disease Control and Prevention (CDC). Symptoms and Care of RSV.
• American Academy of Pediatrics (AAP). Respiratory Syncytial Virus (RSV): What Parents Need to Know.
• Mayo Clinic. Bronchiolitis – Symptoms and causes.
• National Institute for Health and Care Excellence (NICE). Bronchiolitis in children: diagnosis and management (NG9).
⚠️ Medical Disclaimer
This article is for educational purposes only and does not replace professional medical advice.
If your baby is struggling to breathe, feeding poorly, becoming unusually sleepy or showing any warning signs described above, seek urgent medical care immediately.