Sounds like 'ME-poe-LIZ-ue-mab'

Mepolizumab is used to treat severe asthma. Find out how to take it safely and possible side effects.

Type of medicine Also called
  • Medicine for severe asthma
  • Monoclonal antibody
  • Nucala®

What is mepolizumab?

Mepolizumab is used to treat severe asthma. Some people with severe asthma have too many eosinophils (a type of disease-fighting white blood cell) in their blood and lungs. Too many eosinophils can cause asthma flare-ups. Mepolizumab works by reducing the number of eosinophils by limiting how many are produced. This reduces worsening of symptoms during an asthma attack and how often you get asthma flare-ups. 

In New Zealand mepolizumab is available as an injection, which is given under your skin by a healthcare professional to prevent asthma flare-ups.    

Mepolizumab does not give immediate relief from an asthma attack
If you have an asthma action plan that you have agreed with your doctor, follow it closelyat all times.
For severe asthma symptoms, you should use your reliever inhaler immediately and call an ambulance on 111 or go to your nearest Accident & Emergency clinic.


  • The usual dose of mepolizumab to prevent severe asthma is 100 mg injection, given every 4 weeks.
  • Mepolizumab injection is given under your skin (called subcutaneous) into your upper arm, thigh or abdomen.
  • One the day of your injection, take your asthma medication as usual. If you are taking steroid tablets, ask your doctor if you need to decrease your dose.
  • If you miss a dose of mepolizumab, contact your doctor or hospital as soon as possible to re-schedule your appointment.

Precautions before having mepolizumab

  • Are you pregnant or breastfeeding?
  • Do you have a parasitic (helminth) infection?
  • Are you taking other medicines?

If so, it’s important that you tell your doctor before you start mepolizumab. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

What are the side effects of mepolizumab?

Like all medicines, mepolizumab can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Side effects What should I do?
  • Pain and discomfort at the injection site including redness, swelling, itching and a burning sensation of the skin near where the injection was given
  • This is quite common.
  • This usually passes with time. 
  • Tell your doctor if troublesome.
  • Headache
  • This is very common (more than 1 in 10 people are affected).
  • This usually passes with time.
  • Tell your doctor if troublesome.
  • Back pain
  • Sore throat
  • Cough
  • Stuffy nose
  • Stomach pain or discomfort in the upper part of your stomach
  • Fever (high temperature)
  • Nausea or vomiting
  • Dizziness
  • Tell your doctor if troublesome.
  • Signs of an allergic reaction such as difficulty breathing, rash, hives or itching
  • You will be observed during the injection and asked to wait after the injection to make sure you don't have any allergic reactions. 
  • If these happen afterwards, contact your doctor immediately or call 111. 
For more information on side effects, see the Medsafe consumer information leaflet Nucala

Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product

Learn more

The following links provide further information on mepolizumab.

Medsafe Consumer Information Sheets: Nucala


  1. Mepolizumab New Zealand Formulary
Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 20 Mar 2020