Fasenra (Benralizumab) - Subcutaneous

What Is Fasenra?

Fasenra (benralizumab) is an injectable prescription drug used with other drugs to prevent symptoms in adults and adolescents 12 years and older with eosinophilic asthma. Eosinophilic asthma is a rare, severe type of asthma caused by eosinophils, a type of white blood cell associated with inflammation. This medication is used in people whose asthma is not controlled with other treatments.

Fasenra is in a drug class called monoclonal antibodies. It works by reducing eosinophils, which contribute to asthma symptoms. This helps decrease swelling and irritation of the airways, making it easier to breathe.

Fasenra is available as a subcutaneous (under the skin) injection in two different products: a prefilled syringe, which a healthcare provider administers, and an auto-injector pen, which can be given by a caregiver or self-administered with appropriate training.

Drug Facts

Generic Name: Benralizumab

Brand Name(s): Fasenra

Drug Availability: Prescription

Therapeutic Classification: Anti-asthma

Available Generically: No

Controlled Substance: N/A

Administration Route: Subcutaneous

Active Ingredient: Benralizumab

Dosage Form(s): Solution

What Is Fasenra Used For?

The Food and Drug Administration (FDA) approved Fasenra to be used with other drugs for maintenance treatment (to prevent symptoms) of severe eosinophilic asthma in adults and adolescents ages 12 years and older.

In clinical studies, people who took Fasenra had fewer asthma attacks that required hospitalization (and/or an emergency room visit). They also were able to lower the dose of oral steroids.

Fasenra can not be used to treat other eosinophilic conditions or relieve acute asthma attacks or bronchospasm (narrowing of the airways).

Fasenra (Benralizumab) Drug Information - Illustration by Zoe Hansen

Verywell / Zoe Hansen

How to Take Fasenra

If you are prescribed Fasenra and you or your caregiver will be administering it:

  • Read the prescription label and the information leaflet that comes with your prescription.
  • Consult your healthcare provider if you have any questions.
  • Do not use Fasenra until you have been trained by your healthcare provider.
  • Before you start treatment and during treatment with Fasenra, your healthcare provider will order blood work. 
  • Use Fasenra and your other asthma medications as directed by your healthcare provider. Do not change doses or medications unless your healthcare provider tells you to. Tell your healthcare provider if any of your medicines seem to stop working.

Fasenra comes in two administration forms: a single-dose auto-injector and prefilled syringe. The prefilled syringe can only be administered by a healthcare provider. You may self-administer the single-dose auto-injector after your healthcare provider trains you.

To prepare and administer the single-dose auto-injector:

  • Take the pen (each Fasenra pen contains one dose) out of the refrigerator and let it come to room temperature. This takes about 30 minutes. 
  • Do not shake the pen at any time. 
  • While waiting, gather alcohol wipes, a cotton ball or gauze, a bandage, and your sharps disposal container. 
  • Wash your hands with soap and water. Clean your injection site with an alcohol wipe. If you are injecting yourself, the recommended site is the front of the thigh or the lower stomach. If a caregiver injects you, they can inject you in the upper arm, thigh, or stomach. Do not try to inject your own arm. Do not inject Fasenra within 2 inches of your belly button or into damaged skin. Rotate injection sites - with each injection, use a spot at least 1 inch away from the previous injection. 
  • Pull the cap straight off without touching the needle guard or needle. 
  • Hold the Fasenra pen at a 90-degree angle, flat against the site where you will be injecting. You can inject with or without pinching the skin around the injection site. 
  • Press down firmly and hold. You will hear a click. This means the injection has begun. Hold the pen in place for 15 seconds without moving it. A second click indicates that the injection is finished. 
  • Lift the pen straight up. The needle guard will lock into place. Apply gentle pressure to the area with gauze or a cotton ball until bleeding (if any) stops. Then, place a bandage over the injection site. Place the Fasenra pen in a sharps container right away. Never attempt to reuse a Fasenra pen. 

Ask your healthcare provider if you have any questions or concerns about Fasenra.


Store Fasenra in the refrigerator (between 36 degrees and 46 degrees Fahrenheit [F]) in its original packaging until you are ready to use it. You can keep Fasenra at room temperature (68 to 77 degrees F) for 14 days. Once at room temperature, Fasenra must be used within 14 days or thrown away.

Keep Fasenra out of reach and out of sight of children. Do not freeze the medication or expose it to heat. Do not use Fasenra if it has been frozen or passed the expiration date.

How Long Does Fasenra Take to Work?

People taking Fasenra may see improvement relatively quickly. The results of one clinical trial showed a decrease in eosinophil counts within 24 hours. In another trial, there was a significant decrease in eosinophils four weeks after treatment, which was the first time they were measured.

What Are the Side Effects of Fasenra?

Like other medications, Fasenra can cause side effects. Tell your healthcare provider about any side effects you experience while taking this medication.

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at fda.gov/medwatch or 1-800-FDA-1088.

Common Side Effects

The most common side effects of Fasenra are:

  • Headache 
  • Sore throat
  • Fever
  • Hypersensitivity reaction (see below)
  • Injection site reaction

Severe Side Effects

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Hypersensitivity reaction or anaphylaxis: Symptoms can include rash, hives, swelling around the lips, tongue, and face, and difficulty breathing, and require emergency medical attention. 

Long-Term Side Effects

Many people tolerate Fasenra well. However, long-term or delayed side effects are possible. Long-term side effects may include viral upper respiratory infection or bronchitis.

Some people who take Fasenra develop an antibody that blocks the drug. This can happen with any monoclonal antibody treatment and occurs in about 5% of people who use Fasenra. Even so, developing an antibody to the drug is not expected to reduce the benefits of treatment.

Report Side Effects

Fasenra may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Fasenra Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For injection dosage forms (prefilled syringe or prefilled autoinjector):
    • For severe asthma:
      • Adults and children 12 years of age and older—30 milligrams (mg) injected under your skin once every 4 weeks for the first 3 doses, then once every 8 weeks.
      • Children younger than 12 years of age—Use and dose must be determined by your doctor.


Fasenra is available as a single-dose prefilled syringe, which a healthcare provider administers, or a single-dose auto-injector pen, which can be given by a caregiver or self-administered. You and your healthcare provider will determine which option is best for you.

If you are pregnant or plan to become pregnant, talk to your healthcare provider before taking Fasenra. If you take Fasenra and find out you are pregnant, contact your healthcare provider for medical advice. It is not known if Fasenra can harm an unborn baby. There is a pregnancy registry for women who use Fasenra during pregnancy. Your healthcare provider can give you more information about the registry if needed.

Talk to your healthcare provider if you are breastfeeding or planning to breastfeed. This medication may be excreted in breast milk.

Fasenra has not been studied in people with kidney or liver problems. Consult your healthcare provider before taking Fasenra to ensure it is safe for you.

Missed Dose

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

Overdose: What Happens If I Take Too Much Fasenra?

In clinical trials, no dose-related toxicities were reported in people receiving up to 200 milligrams (mg) of Fasenra. There is no specific treatment in the event of an overdose. However, if you take too much Fasenra, you may be treated for any adverse side effects and monitored by a healthcare provider as necessary.

What Happens If I Overdose on Fasenra?

If you think you or someone else may have overdosed on Fasenra, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Fasenra, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly and to check for unwanted effects.

This medicine may cause serious allergic reactions, including anaphylaxis and angioedema. These can be life-threatening and require immediate medical attention. Tell your doctor right away if you have a rash, itching, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth after using this medicine.

This medicine will not stop an asthma attack that has already started. Your doctor may prescribe another medicine for you to use in case of an asthma attack.

If you use a corticosteroid medicine (inhaled or taken by mouth) to control your asthma, keep using it unless your doctor tells you otherwise.

What Are Reasons I Shouldn’t Take Fasenra?

Fasenra is not appropriate for everyone. You should not take this medication if you are allergic to benralizumab or any of the inactive ingredients in Fasenra.

Fasenra also is contraindicated (meaning it should not be used) in acute asthma, acute bronchospasm, or status asthmaticus. Status asthmaticus is a life-threatening asthma exacerbation that does not respond to initial treatments. 

Fasenra may be prescribed with caution in some people, only if the healthcare provider determines it is safe. This includes people at risk for parasitic worm infection. 

What Other Medications May Interact With Fasenra?

No drug interaction studies have been conducted with Fasenra. It is not expected to have significant interactions with other drugs. However, caution is always advised when multiple drugs are taken together. Tell your healthcare provider about all of your medicines, including prescription and over-the-counter (OTC) medicines and vitamins or supplements.

What Medications Are Similar?

Fasenra is a monoclonal antibody prescribed in addition to other medications for severe eosinophilic asthma that has not responded to other treatments.

Other monoclonal antibodies used for asthma include:

  • Cinqair (reslizumab) can be used in adults 18 years and older (in addition to other medications) with severe eosinophilic asthma.
  • Dupixent (dupilumab) can be used in adults and children 6 years and older (in addition to other medications) who have moderate to severe eosinophilic asthma or who depend on oral steroid treatment.
  • Nucala (mepolizumab) can be used in adults and children ages 6 years and older (in addition to other medications) with severe eosinophilic asthma.
  • Xolair (omalizumab) can be used in adults and children 6 years and older with moderate to severe persistent asthma not controlled with inhaled steroids. People must have a positive skin test or react to a perennial (year-round) allergen.

People who take Fasenra typically take other medications for asthma as well, such as short-acting beta-agonists or long-acting beta-agonists (LABAs). Rescue inhalers are a common type of medication used for acute asthma exacerbations or before exercise in people with exercise-induced bronchospasm.

Examples of rescue inhalers include:

  • ProAir HFA (albuterol)
  • Proventil HFA (albuterol)
  • Ventolin HFA (albuterol)
  • Xopenex HFA (levalbuterol)

Long-acting beta-agonists, or LABAs, are available as single-ingredient products but should never be taken alone. LABAs should always be taken with an inhaled steroid, either as two individual products or as a combination product. Serevent (salmeterol) is an example of a LABA.

Some examples of inhaled steroids include:

  • Alvesco (ciclesonide)
  • Asmanex (mometasone)
  • Flovent HFA (fluticasone)
  • Pulmicort Flexhaler (budesonide)
  • Qvar RediHaler (beclomethasone)

Some combination inhaled drugs contain both a steroid and a LABA. Examples include:

  • Advair Diskus (fluticasone and salmeterol)
  • Breo (fluticasone and vilanterol)
  • Dulera (mometasone and formoterol)
  • Symbicort (budesonide and formoterol)

Trelegy Ellipta, another asthma medication, contains three drugs: a steroid (fluticasone), an anticholinergic drug (umeclidinium), and a LABA (vilanterol). There are also a variety of other drugs that may be prescribed for asthma maintenance, for example, oral medications like Singulair (montelukast) or oral steroids such as prednisone.

This list is a list of drugs also prescribed for asthma. It is NOT a list of drugs recommended to take with Fasenra. Ask your pharmacist or a healthcare provider if you have questions.

Frequently Asked Questions

  • What is Fasenra used for?

    Fasenra is a prescription drug that is given by injection under the skin. It is used with other medications to prevent symptoms of severe eosinophilic asthma in adults and adolescents 12 years and older. Eosinophilic asthma is a rare and severe type of asthma caused by a type of white blood cell called eosinophils.

  • How does Fasenra work?

    Fasenra works by reducing eosinophils. This helps prevent asthma symptoms.

  • What drugs should not be taken with Fasenra?

    Fasenra has no documented drug interactions. However, the prescribing information recommends using caution with multiple drugs. Tell your healthcare provider about all of your medications, including prescription, OTC drugs, vitamins, and supplements.

  • How long does it take for Fasenra to work?

    Fasenra may start working very quickly. In one clinical trial, there were lower levels of eosinophils seen in 24 hours. Another clinical trial measured a significant decrease in eosinophils within four weeks, which was the first time they were measured.

  • What are the side effects of Fasenra?

    The most common side effects of Fasenra are headache, sore throat, fever, and injection site reactions. Severe allergic reactions can also occur. If you have hives, difficulty breathing, or swelling around the face, lips, tongue, or throat, get emergency medical help right away. Parasitic worm infections are also a potentially serious side effect of Fasenra.

  • How do I stop taking Fasenra?

    Fasenra is administered once every four weeks for the first three doses. After that, Fasenra is administered once every eight weeks. Your healthcare provider will advise you on how long to take Fasenra. Do not stop taking the medication without guidance from your healthcare provider.

How Can I Stay Healthy While Taking Fasenra?

Before taking Fasenra, discuss your medical history and all medications you take with your healthcare provider. Make sure to follow your healthcare provider’s instructions for use. Read the patient information leaflet with your prescription and ask your healthcare provider if you have any questions.

A healthcare provider should train you or your caregiver on injecting the dose. It can feel intimidating at first to give yourself an injection, but after a few times, your comfort level will increase, and you will feel more confident in your ability to inject yourself.

Your healthcare provider will instruct you if you need to change your other medications. Do not stop taking your steroid medications unless your healthcare provider has instructed you to.

Fasenra does not treat an acute exacerbation of asthma or acute bronchospasm. Always carry a rescue inhaler, which is fast-acting. It can be helpful to have two rescue inhalers, one to keep at home and one at work or school. Be sure to regularly check the expiration date and how many puffs are remaining. Call in refills to the pharmacy several days ahead to ensure you never run out. 

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. U.S. National Library of Medicine. DailyMed. Label: Fasenra - benralizumab injection, solution.

  2. MedlinePlus. Benralizumab injection.

  3. Food and Drug Administration. Drug trials snapshots: Fasenra.

  4. AstraZeneca. Fasenra instructions for use.

  5. Epocrates. Fasenra.

  6. FitzGerald JM. Abstract 2676. Presented at: American Thoracic Society International Conference; May 17-22, 2019; Dallas, Texas.

  7. Food and Drug Administration. Fasenra prescribing information.

By Karen Berger, PharmD
Karen Berger, PharmD, is a community pharmacist and medical writer/reviewer.