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Nucala (mepolizumab)

What is Nucala?

Nucala is a medicine for patients with asthma who continue to have severe asthma attacks, despite taking all of their other currently prescribed asthma medications. It is an add-on maintenance drug, which means that it is taken regularly and in addition to other medications to help prevent asthma attacks. Nucala is approved by the United States Food and Drug Administration (FDA) for treating patients with severe eosinophilic asthma who are aged 12 years and over. Nucala has also been approved to treat eosinophilic granulomatosis with polyangiitis (EGPA), a rare asthmatic condition.1

What is the ingredient in Nucala?

The active ingredient in Nucala is mepolizumab, which is a type of drug called a humanized interleukin-5 antagonist monoclonal antibody.1

How does Nucala work?

Monoclonal antibodies are created in a laboratory to bind to specific substances in the body. Nucala contains mepolizumab, a monoclonal antibody that targets interleukin-5. Interleukin-5 is a chemical messenger that triggers the release of a certain type of white blood cell (called eosinophils) in the bloodstream. Eosinophils are known to be linked to the development of asthma. By blocking the release of eosinophils, Nucala can reduce the inflammation in the airways that can trigger an asthma attack.2,3

In clinical trials comparing Nucala to placebo, patients who received the Nucala injection had:

  • A smaller number of exacerbations (asthma attacks) requiring treatment in the hospital or emergency room
  • A longer time until the first exacerbation after starting treatment
  • Greater decrease in the dose needed for their oral corticosteroid maintenance treatment

However, patients treated with the Nucala injections during the studies did not experience any significant improvement in lung function. Lung function was measured by the quantity of air the patient can exhale in one second.1

What are the possible side effects of Nucala?

The most common side effects that were reported by patients treated with Nucala during clinical studies were injection site reactions. These include pain, redness, itching, swelling, and burning. Other side effects that patients reported were:

  • Headache
  • Back pain
  • Weakness1

For a small number of people, treatment with Nucala can cause more serious side effects. For example, some people may have an allergic reaction to the medicine. Seek medical care right away if you experience any symptoms of an allergic reaction, such as:

  • Swelling of the face, mouth, or tongue
  • Feeling faint, dizzy, or lightheaded
  • Hives
  • Breathing trouble
  • Rash1

A small number of people treated with Nucala develop shingles due to an infection called Herpes Zoster.1

Things to know about Nucala

Nucala is approved for patients 12 years of age and older who have asthma that is not controlled well enough with their current asthma medications. It is not known if Nucala is safe for children younger than 12 years.1

The effect of Nucala on women who are pregnant or breastfeeding is not yet known, but in some cases women can work with their healthcare providers to decide if taking Nucala is right for them. Be sure to let your healthcare provider know if you are pregnant or planning to become pregnant while taking Nucala.1

Nucala is not a “rescue” medication, so it should not be used to treat asthma attacks or sudden breathing problems. Nucala works by lowering the number of eosinophils in the patient’s bloodstream, but it should not be used to treat other types of conditions that are caused by eosinophils.1

Before prescribing Nucala, healthcare providers need to know if you:

  • Have a type of parasitic infection called “helminth”
  • Have never had chickenpox or the vaccine for chicken pox
  • Are taking any kinds of oral or inhaled corticosteroid medications
  • Are taking any other medications, vitamins, or supplements1

Dosing information

Nucala is an injectable medication that is administered to the patient once every four weeks through a shot in the upper arm, abdomen, or thigh. If you start treatment with Nucala, it is important not to stop taking your other kinds of asthma medications, especially any corticosteroids. This can cause your asthma symptoms to get worse again.1

For more information on Nucala, read the full prescribing information.

Written by: Sarah O'Brien and Emily Downward | Last Reviewed: September 2019.
  1. Nucala Prescribing Information. GlaxoSmithKline. Available at Accessed 4/5/18.
  2. Greenfeder S, Umland SP, Cuss FM, Chapman RW, Egan RW. Th2 cytokines and asthma — The role of interleukin-5 in allergic eosinophilic disease. Respiratory Research. 2001;2(2):71-79. doi:10.1186/rr41.
  3. Nucala product website. GlaxoSmithKline. Available at Accessed 4/5/18.