Skip to main content

Mepolizumab

Pronunciation: meh-po-liz-u-mab
Generic name: mepolizumab
Brand name: Nucala
Dosage form: single-dose prefilled autoinjector (100 mg/mL), single-dose prefilled syringe (100 mg/mL, 40 mg/0.4 mL), vial for subcutaneous injection (100 mg)
Drug class: Interleukin inhibitors

Medically reviewed by Carmen Pope, BPharm. Last updated on May 29, 2025.

What is Mepolizumab?

Mepolizumab is used to treat the following eosinophil-related conditions: severe eosinophilic asthma, eosinophilic COPD, chronic rhinosinusitis with nasal polyps (CRSwNP), eosinophilic granulomatosis with polyangiitis (EGPA), and hypereosinophilic syndrome (HES). It can be self-administered by subcutaneous injection every 4 weeks, or a healthcare provider or caregiver can give it. The brand name is Nucala.

Mepolizumab is an interleukin inhibitor that works by lowering the number of eosinophils in your blood. These are white blood cells that cause inflammation in your body. The drug blocks a protein called interleukin-5 (IL-5) that normally tells eosinophils to grow and multiply. This mechanism means fewer eosinophils and less inflammation.

The FDA approved mepolizumab on November 4, 2015, under the brand Nucala, made by GlaxoSmithKline (GSK). There is no generic or biosimilar.

FDA approvals and indications

Mepolizumab is approved for: 

Mepolizumab is not FDA-approved in:

Side effects 

The most common side effects of mepolizumab are:

Serious side effects and warnings

Mepolizumab can cause the following serious side effects.

Allergic reactions. Mepolizumab may cause serious hypersensitivity reactions, including potentially life-threatening anaphylaxis. These reactions can develop within hours or even days after your injection. Seek emergency medical help immediately if you notice:

Herpes Zoster (Shingles) risk. Patients receiving Nucala have an increased risk of developing herpes zoster infections that can cause shingles. Contact your healthcare provider if you develop:

Steroid medication warning: If you're currently using oral or inhaled steroids alongside mepolizumab, never stop them suddenly without medical supervision. Consult your healthcare provider about proper tapering protocols.

This information doesn't cover all possible side effects of mepolizumab. For comprehensive information, always consult the official Nucala Prescribing Information. Report any adverse reactions to your doctor or the FDA's MedWatch program at 1-800-FDA-1088.

Before taking

Do not use mepolizumab if you are allergic to mepolizumab, Nucala, or any inactive ingredients in the injection.

To make sure mepolizumab is safe for you, tell your doctor about all your medical conditions, including if you:

You may need a zoster (shingles) vaccine before you start using mepolizumab.

Pregnancy

It is not known if mepolizumab may harm your unborn baby. Tell your doctor if you become pregnant while using mepolizumab. Your name may be listed on a pregnancy registry to track the effects of mepolizumab on the baby.

Breastfeeding

You and your healthcare provider should decide if you will use mepolizumab and breastfeed. You should not do both without talking with your healthcare provider first.

How is mepolizumab administered?

Mepolizumab is injected under the skin, usually once every 4 weeks.

Read the Instructions for Use in the mepolizumab Package Insert that comes with Mepolizumab for details about the right way to give your injections at home.

Mepolizumab is not a rescue medicine for asthma attacks. Only use a fast acting bronchodilator such as albuterol for an attack. Seek medical attention if your breathing problems get worse quickly, or if you think your asthma medications are not working as well.

Dosing Information

Dose of mepolizumab for severe eosinophilic asthma

Dose of mepolizumab for chronic obstructive pulmonary disease (COPD) in adults

Dose of mepolizumab for chronic rhinosinusitis with nasal polyps (CRSwNP) in adults

Dose of mepolizumab for eosinophilic granulomatosis with polyangiitis (EGPA) in adults

Dose of mepolizumab for hypereosinophilic syndrome (HES)

What happens if I miss a dose?

If you miss a dose, inject a dose as soon as possible. Then continue (resume) your injection on your regular dosing schedule.

If you do not notice that you have missed a dose until it is time for your next scheduled dose, then inject the next scheduled dose as planned. Do not use two doses at one time. If you are not sure when to inject mepolizumab, call your healthcare provider.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using mepolizumab?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

What other drugs will affect mepolizumab?

Tell your doctor about all your current medicines and any you start or stop using, especially:

Other drugs may interact with mepolizumab, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your healthcare providers about all medicines you use now and any medicine you start or stop using. 

Does Mepolizumab interact with my other drugs?

Enter medications to view a detailed interaction report using our Drug Interaction Checker.

Storage

Store the mepolizumab prefilled syringe or mepolizumab autoinjector in the original carton in a refrigerator. Do not freeze or shake the medicine.

You may store the prefilled syringe or autoinjector in the unopened carton at room temperature for up to 7 days.

Safely throw away medicine that is out of date or no longer needed.

Keep out of the reach of children.

Ingredients

Mepolizumab is only available as the brand Nucala.

Active Ingredient: mepolizumab.

Inactive Ingredients (Nucala vials): polysorbate 80, sodium phosphate dibasic heptahydrate, and sucrose.

Inactive Ingredients (Nucala prefilled autoinjectors and prefilled syringes): citric acid monohydrate, EDTA, disodium dihydrate, polysorbate 80, sodium phosphate dibasic heptahydrate, and sucrose.

Mepolizumab for injection is available as:

Who makes Mepolizumab?

Mepolizumab is made by GlaxoSmithKline (GSK) LLC, under the brand Nucala. GSK is located in Philadelphia, PA. 

Mepolizumab Biosimilars

Biosimilar and interchangeable products are biological products that are highly similar to and have no clinically meaningful differences from the reference product.

Reference products

These are biological products that have already been approved by the FDA, against which biosimilar products are compared. There is 1 for mepolizumab.

Nucala (mepolizumab) - GlaxoSmithKline LLC
Formulation type Strength
Autoinjector 100 mg/mL
Autoinjector 100 mg/mL
Pre-Filled Syringe 100 mg/mL
Pre-Filled Syringe 100 mg/mL
Pre-Filled Syringe 40 mg/0.4 mL
Pre-Filled Syringe 40 mg/0.4 mL
Single-Dose Vial 100 mg
Single-Dose Vial 100 mg

View Nucala information in detail.

Popular FAQ

How long does it take for Nucala to work?

Nucala starts working within 48 hours; however, it may take up to 4 weeks before the maximum effect of Nucala is seen for both asthma and eosinophilic granulomatosis with polyangiitis (EGPA). In asthma, the greatest reductions in eosinophils were seen with higher dosages, for example, a 64% reduction in eosinophils was seen with a 12.5mg SC dose and a 90% reduction was seen with a 250mg SC dose after 48 hours.

Continue reading
Can Nucala cause weight gain?

Weight gain has not been reported as a side effect of Nucala during clinical trials. Medications such as corticosteroids that may be used in addition to Nucala for certain conditions are more likely to cause weight gain.

Continue reading
How does Nucala (mepolizumab) work? What is the MOA?

Nucala (mepolizumab) works by lowering the activity of white blood cells called eosinophils. Too many eosinophils can sometimes lead to inflammation in the body. Nucala is a monoclonal antibody that blocks a cytokine called interleukin-5 (IL-5). Continue reading

Can Nucala be self-administered? How is it injected?

Yes, Nucala can be self-administered. Nucala is available as a prefilled syringe or autoinjector that can be self-administered after a doctor has shown you how to administer it. 99% of people can successfully self-administer the Nucala prefilled syringe and 89-95% can successfully administer the Nucala autoinjector.

Continue reading
What is Nucala (mepolizumab) used for and how is it given?

Nucala (mepolizumab) is a biologic therapy used for the treatment of severe eosinophilic asthma, eosinophilic granulomatosis with polyangiitis (EGPA), and hypereosinophilic syndrome (HES). It is given by subcutaneous injection every four weeks. Continue reading

View more FAQ

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.