Last updated on RxList: 1/13/2021
Fasenra Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is Fasenra?

Fasenra (benralizumab) injection is an interleukin-5 receptor alpha-directed cytolytic monoclonal antibody (IgG1, kappa) indicated for the add-on maintenance treatment of patients with severe asthma aged 12 years and older, and with an eosinophilic phenotype.

What Are Side Effects of Fasenra?

Common side effects of Fasenra include:

  • headache,
  • sore throat,
  • fever,
  • hypersensitivity reactions, and
  • injection site reactions (pain, redness, itching, or a small lump)

Dosage for Fasenra?

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

What Drugs, Substances, or Supplements Interact with Fasenra?

Fasenra may interact with other drugs. Tell your doctor all medications and supplements you use.

Fasenra During Pregnancy and Breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant before using Fasenra; it is unknown how it would affect a fetus. Monoclonal antibodies such as Fasenra are transported across the placenta during the third trimester of pregnancy; therefore, potential effects on a fetus are likely to be greater during the third trimester of pregnancy. It is unknown if Fasenra passes into breast milk or how it would affect a nursing infant. Consult your doctor before breastfeeding.

Additional Information

Our Fasenra (benralizumab) Injection, for Subcutaneous Use Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Asthma is a chronic respiratory disease. See Answer
Fasenra Consumer Information

Get emergency medical help if you have signs of an allergic reaction: hives, rash; difficult breathing, feeling light-headed; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • new or worsening asthma symptoms.

Common side effects may include:

  • sore throat; or
  • headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Fasenra (Benralizumab for Subcutaneous Injection)


What Is Asthma? Symptoms, Causes, and Treatments See Slideshow
Fasenra Professional Information


The following adverse reactions are described in greater detail in other sections:

  • Hypersensitivity Reactions [see WARNINGS AND PRECAUTIONS]

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Across Trials 1, 2, and 3, 1,808 patients received at least 1 dose of FASENRA [see Clinical Studies]. The data described below reflect exposure to FASENRA in 1,663 patients, including 1,556 exposed for at least 24 weeks and 1,387 exposed for at least 48 weeks. The safety exposure for FASENRA is derived from two Phase 3 placebo-controlled studies (Trials 1 and 2) from 48 weeks duration [FASENRA every 4 weeks (n=841), FASENRA every 4 weeks for 3 doses, then every 8 weeks (n=822), and placebo (n=847)]. While a dosing regimen of FASENRA every 4 weeks was included in clinical trials, FASENRA administered every 4 weeks for 3 doses, then every 8 weeks thereafter is the recommended dose [see DOSAGE AND ADMINISTRATION]. The population studied was 12 to 75 years of age, of which 64% were female and 79% were white.

Adverse reactions that occurred at greater than or equal to 3% incidence are shown in Table 1.

Table 1. Adverse Reactions with FASENRA with Greater than or Equal to 3% Incidence in Patients with Asthma (Trials 1 and 2)

Adverse Reactions Placebo
Headache 8 6
Pyrexia 3 2
Pharyngitis* 5 3
Hypersensitivity reactions 3 3
* Pharyngitis was defined by the following terms: ‘Pharyngitis’, ‘Pharyngitis bacterial’, ‘Viral pharyngitis’, ‘Pharyngitis streptococcal’.
Hypersensitivity Reactions were defined by the following terms: ‘Urticaria’, ‘Urticaria papular’, and ‘Rash’ [see WARNINGS AND PRECAUTIONS].

28-Week Trial

Adverse reactions from Trial 3 with 28 weeks of treatment with FASENRA (n=73) or placebo (n=75) in which the incidence was more common in FASENRA than placebo include headache (8.2% compared to 5.3%, respectively) and pyrexia (2.7% compared to 1.3%, respectively) [see Clinical Studies]. The frequencies for the remaining adverse reactions with FASENRA were similar to placebo.

Injection Site Reactions

In Trials 1 and 2, injection site reactions (e.g., pain, erythema, pruritus, papule) occurred at a rate of 2.2% in patients treated with FASENRA compared with 1.9% in patients treated with placebo.


As with all therapeutic proteins, there is potential for immunogenicity. The detection of antibody formation is highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay may be influenced by several factors including assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to benralizumab in the studies described below with the incidence of antibodies in other studies or to other products may be misleading.

Overall, treatment-emergent anti-drug antibody response developed in 13% of patients treated with FASENRA at the recommended dosing regimen during the 48 to 56 week treatment period. A total of 12% of patients treated with FASENRA developed neutralizing antibodies. Anti-benralizumab antibodies were associated with increased clearance of benralizumab and increased blood eosinophil levels in patients with high anti-drug antibody titers compared to antibody negative patients. No evidence of an association of anti-drug antibodies with efficacy or safety was observed.

The data reflect the percentage of patients whose test results were positive for antibodies to benralizumab in specific assays.

Postmarketing Experience

In addition to adverse reactions reported from clinical trials, the following adverse reactions have been identified during post approval use of FASENRA. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. These events have been chosen for inclusion due to either their seriousness, frequency of reporting, or causal connection to FASENRA or a combination of these factors.

Immune System Disorders: Hypersensitivity reactions, including anaphylaxis.

Read the entire FDA prescribing information for Fasenra (Benralizumab for Subcutaneous Injection)

© Fasenra Patient Information is supplied by Cerner Multum, Inc. and Fasenra Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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