This product is manufactured by GlaxoSmithKline using the ingredient mepolizumab.

This product is taken via subcutaneous injection.

Why is it prescribed?

Mepolizumab is a subcutaneously injected medicine used in addition to other asthma medicines to treat adult patients with severe eosinophilic asthma, whose asthma is not controlled with their current asthma medicines, such as high-dose inhalers. Severe eosinophilic asthma is a type of severe asthma in which there is a presence of eosinophils (a type of white blood cell). Eosinophils are associated with inflammation of the airways that can cause your asthma to get worse or can increase the number of asthma attacks.  

This medication is given by subcutaneous injection by a trained healthcare professional.

There is a chance it could cause an allergic reaction when injected.  If you have had a similar reaction before, tell your doctor before you are given the injection.

If you have an existing parasitic infection, live in a region where infections caused by parasites are common, or if you are travelling to such a region, talk to your doctor before using Nucala, as it may weaken your resistance to such infections. Parasitic infections should be treated prior to starting treatment with this medication.


See other products used in the treatment of •asthma •

The recommended dose is 100 mg given by subcutaneous injection every four weeks.

Severe eosinophilic asthma is a type of asthma in which there is a presence of eosinophils (a type of white blood cell) in the lungs.  Mepolizumab is a monoclonal antibody that blocks a specific protein called interleukin-5. By blocking the action of interleukin-5,  Mepolizumab limits the production of eosinophils from the bone marrow and lowers the number of eosinophils in the blood and lungs. 


Very common side effects

  • Headache

Common side effects

  • Injection-site reaction (pain, redness, swelling, itching, and burning sensation of the skin near where the injection was given)
  • Back pain
  • Sore throat
  • Congestion, cough, discomfort, fever 
  • Stuffy nose 
  • Stomach pain or discomfort in the upper area of the stomach 
  • Itchy red patches on the skin (eczema)
  • Urinary tract infection (blood in urination, painful and frequent urination, fever, pain in lower back)
  • High temperature 

Consult your physician if any of these side effects worsen or are bothersome.


Mepolizumab should not be given to children and adolescents under 18 years old. 

Mepolizumab is not a substitute for the medicines you are already taking.  It does not treat a sudden asthma attack - do not use for this reason.
Adding mepolizumab to treatment with inhaled steroids (e.g. fluticasone) has been shown to reduce the number of asthma attacks. It has not been proven to work in other allergic conditions.
Oral or inhaled corticosteroids (e.g. prednisone, fluticasone) should not be abruptly stopped upon starting mepolizumab therapy.

Interrupting or stopping treatment with mepolizumab may cause your asthma symptoms and attacks to come back or occur more frequently. If your asthma symptoms get worse while receiving this medication call your doctor.

Use is not recommended in the following situations:

  • allergy to mepolizumab or any component of the formulation

Use in pregnancy and breastfeeding: At this time there is limited information on use in pregnant and breastfeeding women. Consult your doctor or pharmacist before using.

Page Last Updated: 05/10/2016