Eosinophilic lung conditions

An eosinophil is a type of white blood cell. A build-up of eosinophils in the lung can make it hard to breathe. This page has information for parents on eosinophilic lung conditions in children.

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What are eosinophils?

Eosinophils are a type of white blood cell. White blood cells protect us from illness and infection.

Eosinophils are an important part of the immune system and we need them to keep us healthy. But sometimes they are also involved in allergic reactions and inflammation. Too many eosinophils in the lung can cause swelling, which can make it hard to breathe.


What are eosinophilic lung conditions?

Eosinophilic lung conditions happen when there is a build-up of eosinophils in the air spaces and tissue of the lungs. They are very rare in children.

Eosinophilic lung conditions are sometimes called pulmonary eosinophilia or eosinophilic pneumonia.

There are 3 different forms of eosinophilic lung condition:

  • transient: with symptoms that come and go
  • acute: with severe symptoms that come on suddenly, often developing in less than a week
  • chronic: with long term symptoms (lasting longer than 1 month)

What causes eosinophilic lung conditions?

It’s not always possible to work out the cause of an eosinophilic lung condition. Sometimes no cause is found.

Causes can include:

  • parasite infection. This is not a common cause in the UK, where parasite infections are uncommon
  • an allergic reaction, especially to a specific type of mould called aspergillus
  • a reaction to drugs, such as non-steroidal anti-inflammatory drugs like ibuprofen or antibiotics.
  • Sometimes the cause is not obvious. The body produces too many eosinophils, particularly in the lungs. These eosinophils release inflammatory molecules,  chemicals and proteins that can damage the tissues in the lungs. The air sacs in the lungs become inflamed (swollen) and can stop oxygen from getting into the bloodstream.

Read more about how to stop aspergillus growing in your home.


What are the symptoms?

When too many eosinophils are produced in the lungs, this can cause symptoms including:

  • difficulty breathing, chest tightness and pain
  • fever
  • cough
  • wheezing
  • coughing up blood or mucus
  • symptoms that don’t affect the lungs, such as muscle aches or rashes

In severe acute cases, it can cause respiratory failure. This is where there is not enough oxygen in the blood and is a medical emergency.

Call 999 now if your child has any of these breathing-related symptoms:

  • Severe breathing difficulties
  • Grunting with the effort of trying to breathe
  • The muscles under their ribs are sucking in with each breath
  • Fast breathing
  • Your child won’t wake up, or won’t stay awake
  • Breathing stops for more than 20 seconds
  • Regular shorter pauses in their breathing while they are awake
  • Very pale or blue skin, or the inside of their lips and tongue are blue
  • Fitting, if they have never had a fit before

How are eosinophilic lung conditions diagnosed in children?

Your child will need to have one or more tests to diagnose an eosinophilic lung condition. These may include:

  • taking samples of lung fluid. A tube called a bronchoscope is inserted to collect fluid from the lungs. The eosinophils in the lung fluid are counted
  • chest X-ray or CT scan. Damage due to eosinophils show up as shadows on the lung
  • blood tests to find out how many eosinophils are in the blood
  • lung function tests appropriate for the child’s age
  • lung biopsy. This may be needed if the other tests do not give a definite diagnosis. A sample of tissue is taken from the lungs, and the eosinophils are counted.

What are the treatments?

If your child is having difficulty breathing, they may need:

  • corticosteroid medicines to reduce the inflammation in the lungs. This is usually very effective, and the dosage can be lowered as the condition improves. Some newer medicines are being used to improve the outlook and reduce steroid side effects.
  • full intensive care support in hospital, if the condition is life threatening. This may be needed until steroid treatment starts to work.

Treating the underlying cause of the eosinophilic lung condition is important. For example, if a parasite is causing the body to produce too many eosinophils, anti-parasitic medicines will be needed.

If you have concerns or need advice, call our helpline on 03000 030 555 between 9am and 5pm on a weekday or email them.

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Last medically reviewed: December 2019. Due for review: December 2022

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.