An anti-IL5 receptor biologic injection
Benralizumab
An add-on injection for severe eosinophilic asthma that reduces flare-ups by clearing eosinophils.
What is Benralizumab?
Benralizumab is a biologic 'add-on' injection used for severe asthma driven by high levels of eosinophils, a type of white blood cell linked to airway inflammation. It targets the receptor that these cells use to respond to a messenger called IL-5, which helps clear them and reduces asthma flare-ups over time. It is given as an injection under the skin at intervals, with the gaps usually widening after the first few doses, and is generally well tolerated. It is not a reliever and works gradually, so keep using your usual asthma inhalers.
Education and reference only. This is a plain-language guide to Benralizumab — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Benralizumab is a biologic medicine, a laboratory-made antibody, used as an add-on treatment for severe asthma when eosinophils (a white blood cell that drives airway inflammation) remain high despite usual inhalers. It is also used in some people for a blood vessel condition called eosinophilic granulomatosis with polyangiitis. It is given as an injection under the skin, sometimes by a nurse and sometimes by the person or a carer after training.
How it works
Benralizumab attaches to the receptor on eosinophils that responds to interleukin-5 (IL-5). By binding there, it flags these inflammatory cells for removal by the immune system, so their numbers fall quickly and stay low. With fewer eosinophils, the airway inflammation behind severe asthma attacks settles, reducing flare-ups. The benefit builds over weeks, so it is an add-on to, not a replacement for, your regular inhalers.
Company & origin
Originated / developed by: AstraZeneca.
A biologic 'add-on' injection used in the UK for severe asthma driven by high levels of a white blood cell called the eosinophil.
What it treats
Conditions Benralizumab is used for
Practical use
How to take Benralizumab
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given as an injection under the skin; the first few doses are closer together, then the gaps usually widen.
- Keep using your regular asthma inhalers and follow your asthma action plan; this is an add-on, not a replacement.
- Do not use it to relieve an asthma attack, as it does not act quickly; use your rescue inhaler and seek help as advised.
- Some people or carers can give it at home after training, while others have it at the clinic.
- Tell your specialist if your asthma has not improved after several months so they can review treatment.
Weighing it up
Advantages & disadvantages of Benralizumab
Advantages
- Can markedly reduce severe asthma flare-ups in people with high eosinophil levels.
- May help reduce the need for long-term steroid tablets in some people.
- After the first few doses, injections are spaced further apart, which many find convenient.
Disadvantages
- Works gradually over weeks and is not a quick-acting reliever.
- Only suitable for a specific type of severe asthma and must be started by a specialist.
- Can cause headache, sore throat and, rarely, allergic reactions.
Practical use
Good to know
Benralizumab is reserved for severe asthma that stays poorly controlled despite high-dose inhaled treatment, and it is started and supervised by a specialist team. A practical point is the schedule: the first few injections are given closer together, then the gaps widen, which many people find convenient. Like other treatments in its class, it works over weeks to prevent flare-ups and is not a rescue medicine, so keep your reliever inhaler to hand and continue your usual asthma plan. It is generally well tolerated, with headache and sore throat being common. Because it affects part of the immune system, any parasitic infection is usually treated first, and you should report signs of infection. Allergic reactions are uncommon but possible.
Who should not take it / use with caution
- People who have had a serious allergic reaction to benralizumab should not have it again.
- It is used cautiously where a parasitic (worm) infection is present, which is usually treated first.
- Anyone with an active untreated infection should discuss timing with their specialist before starting.
Monitoring
- Reviewing asthma control, flare-up frequency and eosinophil levels to judge benefit.
- Checking for and treating any parasitic infection before and during treatment.
- Watching for allergic reactions, particularly around the first injections.
Side effects
- Headache and sore throat are among the more common effects.
- Injection-site reactions or a raised temperature can occur.
- Rarely, allergic reactions can develop, so early injections may be observed.
Key interactions
- It is not known to have the usual tablet-type drug interactions, but tell your team about all your medicines.
- Discuss live vaccines with your specialist, as your immune response may be affected.
- If you take long-term steroids, reduce them only gradually and under medical guidance.
Available as: Injection given under the skin (prefilled pen or prefilled syringe), with widening intervals after the first doses.
Answers
Benralizumab: frequently asked questions
How is benralizumab different from mepolizumab?
Both target the IL-5 pathway in eosinophilic asthma, but benralizumab acts on the receptor on the cells to clear them, while mepolizumab mops up the IL-5 messenger; your specialist chooses based on your situation.
Why are my injections closer together at first?
The first few doses are given at shorter intervals to get started, after which the gaps widen, which many people find more convenient.
Can I use it during an asthma attack?
No. It is a preventer-type add-on that works over weeks, so use your reliever inhaler for attacks and seek help as advised.
Will it let me reduce my steroid tablets?
It may help some people cut down long-term steroid tablets, but only gradually and under your specialist's guidance.
Can I have my usual vaccinations?
Most vaccines are fine, but check with your specialist about live vaccines, as your immune response may be affected.
The wider class
About Anti-IL5 receptor biologic (severe asthma)
Benralizumab belongs to the anti-il5 receptor biologic (severe asthma) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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