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Fasenra

Generic name: benralizumab

Last updated June 25, 2026 0 views Reviewed by Carmen Pope, Senior Medical Editor, B. Pharm
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What is Fasenra?

Fasenra is used to treat severe eosinophilic asthma, eosinophilic granulomatosis with polyangiitis (EGPA), and hypereosinophilic syndrome (HES). It is a subcutaneous injection given every 4 to 8 weeks, depending on the condition.

Fasenra (benralizumab) targets eosinophils, white blood cells that drive inflammation in the airways (asthma), tissues (EGPA), or blood and tissues (HES). It works by binding to a protein called IL-5Rα (interleukin-5 receptor alpha) on the surface of eosinophils and basophils, which activates natural killer (NK) cells from the immune system. These NK cells then directly destroy the eosinophils through a process called antibody-dependent cell-mediated cytotoxicity (ADCC), reducing eosinophil levels in tissues and blood and helping to reduce inflammation.

Fasenra received FDA approval on November 14, 2017, for eosinophilic asthma. Approval was extended on September 17, 2024, to include EGPA, and on May 13, 2026, to include HES.

Fasenra is approved for:

  • Severe asthma with an eosinophilic phenotype as add-on maintenance treatment in adults and children 6 years and older
  • Eosinophilic granulomatosis with polyangiitis (EGPA) in adults
  • Hypereosinophilic syndrome (HES) without an identifiable nonhematologic secondary cause in adults and children 12 years and older.

How do I use a Fasenra injection?

Do not try to inject Fasenra until you have been shown the right way to do so by your healthcare provider.

  • Read the “Instructions for Use” that comes with Fasenra for information on how to prepare and inject your Fasenra injection.
  • Fasenra is available as a single-dose prefilled syringe and a single-dose autoinjector (Fasenra Pen).
  • A healthcare provider uses the single-dose prefilled syringe to inject Fasenra.
  • In children aged 6 to 11 years, Fasenra should only be given by a caregiver or healthcare provider.

Fasenra is injected under your skin (subcutaneously [SC]):

  • Once every 4 weeks for the first 3 doses and then every 8 weeks for asthma.
  • Once every 4 weeks for EGPA and HES.

If you are giving yourself the Fasenra injection, the recommended injection site is the front of your thigh or the lower part of your stomach (abdomen).

  • In addition to these sites, a caregiver may inject you in the back of the upper arm.

For each injection, choose a different site that is at least 1 inch (3 cm) away from where you last injected. Do not inject:

  • into the 2-inch (5-cm) area around your belly button
  • where the skin is tender, bruised, scaly, or hard
  • into scars or damaged skin
  • through clothing.

Fasenra is not a rescue medicine for asthma attacks.

You may need frequent medical tests to help your doctor determine how long to treat you with Fasenra.

Before taking this medicine

Do not receive a Fasenra injection if you are allergic to benralizumab, Fasenra, or any inactive ingredients in the injection.

Before receiving Fasenra, tell your healthcare provider about all of your medical conditions, includingif 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
  • Are pregnant or plan to become pregnant
  • Are breastfeeding or plan to breastfeed.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Do not stop taking your other medicines for your condition unless your healthcare provider tells you to

Before you start treatment with Fasenra, your doctor may perform tests to measure your eosinophil levels.

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

Pregnancy

It is not known if Fasenra will harm your unborn baby. Tell your healthcare provider if you become pregnant during your treatment with Fasenra.

Breastfeeding

It is not known if Fasenra passes into your breast milk. You and your healthcare provider should decide if you will use Fasenra and breastfeed. Talk to your healthcare provider about the best way to feed your baby if you use Fasenra.

Side effects

Common side effects

The most common side effects of Fasenra according to condition are:

  • Asthma: headache and sore throat
  • EGPA: headache
  • HES: headache, allergic reactions, and flu-like symptoms.

Serious side effects and warnings

Fasenra may cause serious side effects, including:

  • Allergic (hypersensitivity) reactions, including anaphylaxis. Serious allergic reactions can happen after you get your Fasenra 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.

Age restrictions for Fasenra vary by condition:

  • Eosinophilic asthma: not for children under 6
  • EGPA: not for anyone under 18
  • HES: not for children under 12.

Fasenra is not a rescue medicine for asthma attacks. Use only fast-acting inhalation medicine for an attack. Seek medical attention if your fast-acting medicine does not work.

These are not all the possible side effects of Fasenra. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA1088.

The cost of Fasenra varies significantly depending on your insurance coverage. Most patients pay far less than the list price of $6,022 (30mg) or $2,007 (10mg):

  • Employer-provided or Individual Private Policy: ~$46/dose (savings program may reduce to $0 if you are eligible for the Fasenra 360 Savings Program)
  • Medicare Advantage: ~$90/dose
  • Medicaid: ~$2–$9/dose
  • No insurance: varies by pharmacy.

See Fasenra Prices, Coupons, Copay Cards & Patient Assistance for more information.

Dosing information

Dose of Fasenra for Asthma

  • Adults and Pediatrics 12+: 30 mg subcutaneously every 4 weeks for the first 3 doses, followed by 30 mg subcutaneously once every 8 weeks thereafter
  • Pediatrics 6 to 11 years, less than 35 kg: 10 mg subcutaneously every 4 weeks for the first 3 doses, followed by 10 mg subcutaneously once every 8 weeks thereafter
  • Pediatrics 6 to 11 years, 35 kg or more: 30 mg subcutaneously every 4 weeks for the first 3 doses, followed by 30 mg subcutaneously once every 8 weeks thereafter.

Dose of Fasenra for EGPA and HES

  • All patients: 30 mg subcutaneously every 4 weeks

What happens if I miss a dose?

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

What happens if I overdose?

Since this medicine is given by a healthcare professional in a medical setting, an overdose is unlikely to occur.

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

What other drugs will affect Fasenra?

Other drugs may interact with benralizumab, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

How should I store Fasenra?

  • Store Fasenra in the refrigerator between 36°F and 46°F (2°C and 8°C).
  • Store Fasenra in the original carton to protect from light.
  • Fasenra may be stored at room temperature up to 77°F (25°C) for up to 14 days.
  • After Fasenra is removed from the refrigerator and brought to room temperature, it must be used within 14 days or thrown away (disposed of).
  • Do not freeze. Do not shake. Do not expose to heat.
  • Do not use Fasenra past the expiration (EXP) date.

Keep out of the reach of children

What are the ingredients in Fasenra?

Active ingredient: benralizumab

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

Fasenra is manufactured by AstraZeneca AB, Södertälje, Sweden SE-15185, U.S. License Number 2059. It is distributed by AstraZeneca Pharmaceuticals LP, Wilmington, DE 19850.

Common questions about Fasenra

What are Monoclonal Antibodies and how do they work?
Monoclonal antibodies (mAbs) are man-made proteins that mimic the natural antibodies produced by our immune systems. Monoclonal antibodies can be formulated into medicines to treat various types of illnesses, such as cancer, rheumatoid arthritis or psoriasis. Continue reading
Does Fasenra weaken your immune system?
Fasenra does not appear to weaken the immune system, but it does affect how the immune system works. This raises legitimate concerns that it may cause immunosuppression and negatively impact a person's immune response, although no major safety concerns have been identified so far. Continue reading
How long does Fasenra take to work?
Fasenra acts rapidly, reducing blood eosinophil levels within 24 hours across all three indications. In asthma, eosinophil counts reach zero within 7 days and exacerbation rates improve within 4 weeks. For EGPA, steroid reduction is seen by weeks 48–52; for HES, eosinophil suppression is sustained long-term. Continue reading
What is Fasenra used for and how does it work?
Fasenra injection is approved for severe eosinophilic asthma, eosinophilic granulomatosis with polyangiitis (EGPA), and hypereosinophilic syndrome (HES). Fasenra's mechanism of action (MOA) involves specifically targeting eosinophils. Continue reading
What eosinophil count is needed for Fasenra?
Fasenra may be an option for severe asthma if you have an eosinophil count of at least 150-300 cells per microliter (cells/μL), determined from a common blood test, plus you have required an oral corticosteroid treatment (like prednisone) at least twice per year, despite maximum inhalation therapy. Continue reading
What type of asthma is Fasenra used to treat?
Fasenra (benralizumab) is used as an add‑on maintenance treatment for a specific type of asthma called severe eosinophilic asthma in adults and children 6 years and older. It is not a rescue medicine and does not treat sudden asthma attacks or other eosinophilic diseases. Continue reading

Related medicines

Before you take this medicine: the information on this page is general and may not cover your personal circumstances. Read the label supplied with your medicine and ask a pharmacist or doctor if you are unsure, especially if you are pregnant, breastfeeding, taking other medicines or managing a long-term condition.
General medicine information Consumer-friendly language Source: Drugs.com

Content is provided for education and is not medical advice. See our medical disclaimer. Source page medically reviewed by Carmen Pope, Senior Medical Editor, B. Pharm on June 25, 2026.