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Eosinophilic lung conditions

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

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Eosinophilic is pronounced: ‘ee-o-see-no-fil-ick’.

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 can cause problems. For example, too many eosinophils in the lungs 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 three different forms of eosinophilic lung condition: 

  • transient: these have symptoms that come and go
  • acute: this means having symptoms that come on suddenly, often developing in less than a week
  • chronic: this means having long-term symptoms (lasting longer than one month).

What causes eosinophilic lung conditions?

Occasionally the body produces too many eosinophils, particularly in the lungs. These eosinophils release harmful chemicals and proteins that can damage the tissues in the lungs. The air sacs in the lungs then become inflamed (swollen) and can stop oxygen from getting into the bloodstream.

It’s not always possible to work out the cause of an eosinophilic lung condition. But causes can include:

  • an allergic reaction, especially to a specific type of mould called aspergillus – read more about how to stop mould like aspergillus growing in your home
  • a reaction to drugs, such as non-steroidal anti-inflammatory drugs like aspirin, ibuprofen or antibiotics 
  • a parasite infection, this is not a common cause in the UK where parasite infections are rare.

What are the symptoms of an eosinophilic lung condition?

When too many eosinophils are produced in the lungs, it 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, a build-up of eosinophils can cause respiratory failure (when there isn’t enough oxygen in the blood). This 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
  • Their breathing stops for more than 20 seconds on one occasion, or there are regular shorter pauses in their breathing
  • 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 tests to diagnose an eosinophilic lung condition. These may include:

  • blood tests to find out how many eosinophils are in the blood
  • lung function tests
  • 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 
  • chest X-ray or CT scan - damage because of eosinophils can show up as shadows on the lung
  • bronchoalveolar lavage (BAL) - a tube called a bronchoscope is inserted into the airways and saline solution is passed through this tube to wash out the cells. This fluid is collected, and the tubing is removed. The cells in the fluid are then looked at and counted under a microscope.     

How are eosinophilic lung conditions treated?

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

  • steroid medicines to reduce the inflammation in their lungs. This is usually very effective, and the dosage can be lowered as the condition improves 
  • non-steroidal medicines to improve the outlook and avoid steroid side effects 
  • oxygen therapy to help their breathing 
  • full intensive care support in hospital if the condition is life-threatening. This may be needed until the 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, your child will be given anti-parasitic medicines.

What’s the outlook for eosinophilic lung conditions?

The severity of eosinophilic lung conditions, their cause and how bad the symptoms are can vary a lot between children. This makes it difficult to know the outlook, as it will be different for each child. However, generally, if an eosinophilic lung condition is diagnosed and treated quickly, the outlook is very good. People with an eosinophilic lung condition usually respond to treatment quickly, without any long-term complications. 

More help and support

Looking after a child with an eosinophilic lung condition can be difficult. It’s important you take time to take care of yourself, as well as your child. Talk to your doctor or nurse if you feel like you’re struggling to cope. You can always call our helpline – our friendly team can help answer your questions or worries. Call 0300 222 5800, Monday to Friday between 9am – 5pm (excluding Bank Holidays).

You may also want to join our Parent and Carer Support Network which provides support and a space for parents and carers of children with lung conditions to come together.

We use your comments to improve our information. We cannot reply to comments left on this form. If you have health concerns or need clinical advice, call our helpline on 03000 030 555 between 9am and 5pm on a weekday or email them.

Last medically reviewed: August 2022. Due for review: August 2025

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.