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Generic name: benralizumab
Brand name: Fasenra
Dosage form: subcutaneous injection
Drug class: Interleukin inhibitors

Medically reviewed by Philip Thornton, DipPharm. Last updated on Apr 4, 2023.

What is benralizumab?

Benralizumab is a biological drug called a monoclonal antibody. It is an injectable medication used as an add-on therapy to prevent eosinophilic asthma, a chronic inflammatory disease that causes your airways to narrow and swell, making it difficult to breathe.

Eosinophilic asthma is a rare type of asthma caused by high levels of eosinophils, a type of white blood cell and part of your immune system. Eosiniphils are involved in fighting infections and causing inflammation.

Benralizumab works by binding to the alpha subunit of the human interleukin-5 receptor (IL-5Rα) on the surface of eosinophils, which signals other cells of your immune system to kill these inflammation-causing cells. This process reduces the number of eosinophils in your blood and is called antibody-dependent cell-mediated cytotoxicity (ADCC).

Benralizumab was approved by the US Food and Drug Administration (FDA) in 2017. No biosimilars of benralizumab have been approved. Biosimilars are highly similar versions of a biological drug that are designed to have the same effect on a person, but a biosimilar is not identical to the original version of the drug.

What is benralizumab used for?

Benralizumab is a prescription medicine used with other asthma medicines for the maintenance treatment of asthma in people 12 years and older whose asthma is not controlled with their current asthma medicines. Benralizumab helps prevent severe asthma attacks (exacerbations) and may improve your breathing.

  • Benralizumab is not used to treat other problems caused by eosinophils.
  • Benralizumab is not used to treat sudden breathing problems. Tell your healthcare provider if your asthma does not get better or if it gets worse after you start treatment with benralizumab.

It is not known if benralizumab is safe and effective in children under 12 years of age.

Who should not take benralizumab?

Do not use benralizumab if you are allergic to benralizumab or any of the ingredients in benralizumab. See below for a complete list of ingredients in benralizumab.

What should I tell my doctor before taking benralizumab?

Before using benralizumab, tell your healthcare provider about all of your medical conditions, including if you:

  • are taking oral or inhaled corticosteroid medicines. Do not stop taking your corticosteroid medicines unless instructed by your healthcare provider. This may cause other symptoms that were controlled by the corticosteroid medicine to come back.
  • have a parasitic (helminth) infection.

Do not stop taking your other asthma medicines unless your healthcare provider tells you to.

How should I take benralizumab?

  • Benralizumab is injected under your skin (subcutaneously) one time every 4 weeks for the first 3 doses, and then every 8 weeks.
  • Benralizumab comes in a single dose prefilled syringe and in a single dose autoinjector.
  • A healthcare provider will inject benralizumab using the single-dose prefilled syringe.
  • If your healthcare provider decides that you or a caregiver can give the injection of benralizumab, you or your caregiver should receive training on the right way to prepare and give the injection using the benralizumab pen.
  • Do not try to inject benralizumab until you have been shown the right way by your healthcare provider. See the detailed “Instructions for Use” that comes with benralizumab pen for information on how to prepare and inject benralizumab.

What happens if I miss a dose?

If you miss a dose of benralizumab, call your healthcare provider.

Dosing information

The recommended dose of benralizumab is 30 mg every 4 weeks for the first 3 doses, followed by once every 8 weeks thereafter.

Benralizumab is administered by subcutaneous injection.

What are the side effects of benralizumab?

Benralizumab may cause serious side effects, including:

  • allergic (hypersensitivity) reactions, including anaphylaxis. Serious allergic reactions can happen after you get your benralizumab injection. Allergic reactions can sometimes happen hours or days after you get your injection. Tell your healthcare provider or get emergency help right away if you have any of the following symptoms of an allergic reaction:
    • swelling of your face, mouth and tongue
    • breathing problems
    • fainting, dizziness, feeling lightheaded (low blood pressure)
    • rash
    • hives

The most common side effects of benralizumab include headache and sore throat.

These are not all the possible side effects of benralizumab.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Pregnancy and breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant. It is not known if benralizumab will harm your unborn baby. Tell your healthcare provider if you become pregnant during your treatment with benralizumab.

There is a pregnancy registry for women who use benralizumab while pregnant. The purpose of the registry is to collect information about the health of you and your baby. You can talk to your healthcare provider about how to take part in this registry or you can get more information and register by calling 1‑877-311-8972 or go to

Tell your doctor if you are breastfeeding or plan to breastfeed. It is not known if benralizumab passes into your breast milk. You and your healthcare provider should decide if you will use benralizumab and breastfeed. Talk to your healthcare provider about the best way to feed your baby if you use benralizumab.


  • Store benralizumab in the refrigerator between 36°F to 46°F (2°C to 8°C).
  • Benralizumab may be stored at room temperature between 68°F to 77°F (20°C to 25°C) for up to 14 days.
  • Once removed from the refrigerator and brought to room temperature benralizumab must be used within 14 days or thrown away.
  • Store benralizumab in the original carton until you are ready to use it to protect it from light.
  • Do not freeze benralizumab. Do not use benralizumab that has been frozen.
  • Do not expose benralizumab to heat.
  • Do not use benralizumab past the expiration date.
  • Keep benralizumab and all medicines out of the reach of children.

What are the ingredients in benralizumab?

Active ingredient: benralizumab

Inactive ingredients: L-histidine, L-histidine hydrochloride monohydrate, polysorbate 20, α,α-trehalose dihydrate, and Water for Injection.

Benralizumab is manufactured under the brand name Fasenra by AstraZeneca AB, Södertälje, Sweden SE-15185.

Frequently asked questions

Further information

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