Severe asthma biologics: how biological treatments work and who can have them

The NHS says that if you have severe asthma that is not controlled by inhalers and tablets, you may be offered other treatments, such as injected medicines called biological therapies. Asthma + Lung UK describes biologics as treatments that target the immune system and reduce inflammation in the airways. They are based on monoclonal antibodies, which are made in a laboratory and are like the antibodies that exist naturally in the body.

Inflammation in the lungs can sometimes be caused by allergies or by a type of white blood cell called an eosinophil. In some people with severe asthma there are too many eosinophils in the blood, which can make airway inflammation worse. Biologics block the changes that cause that inflammation.

A Scottish Government prescribing guide similarly describes monoclonal antibodies as medicines that target specific biological processes and that currently target either allergic asthma or eosinophilic asthma. It says they have been shown to significantly reduce asthma exacerbations, hospital admissions and oral corticosteroid use.

Biologics are a specialist, targeted treatment. In general, Asthma + Lung UK says they might help if you are having a lot of asthma attacks, taking a lot of oral steroids, finding that other treatments are not helping, and a lung specialist thinks a biologic could help your type of asthma.

Before considering a biologic, specialists usually check that the basics are in place. They may do a blood test to count eosinophils, a FeNO test to see how inflamed the airways are, check other health conditions are managed, and make sure existing medicines are being used properly, including inhaler technique and support to stop smoking.

If biologics are not right, the specialist can discuss other options. Asthma + Lung UK mentions bronchial thermoplasty and other specialist treatments as examples.

Asthma + Lung UK lists the six asthma biologics and how they are given. Your specialists decide which is right, which depends on your type of asthma and the results of tests.

• Mepolizumab (Nucala): every four weeks, by injection.

• Reslizumab (Cinqaero): every four weeks, through a drip.

• Benralizumab (Fasenra): every four weeks for the first three treatments, then every eight weeks, by injection.

• Omalizumab (Xolair and Omlyclo): every two to four weeks, by injection.

• Dupilumab (Dupixent): every two weeks, by injection.

• Tezepelumab (Tezspire): every four weeks, by injection.

You will need to visit a specialist severe asthma centre to start treatment. The nearest clinic may not be in your local area, so Asthma + Lung UK suggests thinking about travel time and costs and notes there is NHS advice about help with travel costs and asking for time off work for appointments.

If it is safe and right for you, your specialist can teach you or a carer to inject at home. Biologics come in prefilled syringes or pens that need storing in the fridge.

Specialists review treatment regularly. If you have been using steroid tablets long term, Asthma + Lung UK says you should see the specialists every four to eight weeks, and they may suggest gradually stopping the tablets if it is right for you. If you have not been taking steroid tablets long term, reviews are every three to six months.

At six months you and the specialists assess how well the biologic is working, which may include an Asthma Control Test, spirometry and blood tests. If it is working and symptoms are improving you can keep using it long term. If it is not, you might stop or change treatment, for example by trying a different biologic.

Like all medicines, biologics can have side effects, and these differ between medicines. The patient information leaflet lists them, and side effects can be reported to the Yellow Card Scheme.

Biologics can cause severe allergic reactions (anaphylaxis) in some people, usually within two hours of taking them. Asthma + Lung UK says that in most biologics it is uncommon, and that it is more likely in people with a history of severe allergic reactions. It advises calling 999 if your lips, mouth, throat or tongue suddenly swell, you are breathing very fast or struggling to breathe, your throat feels tight or you are struggling to swallow, your skin, tongue or lips turn blue, grey or pale, you become suddenly very confused or drowsy, or someone faints and cannot be woken. A swollen, raised or itchy rash may also occur.

Asthma + Lung UK says you should be able to keep using biologics for severe asthma while pregnant, breastfeeding or thinking of getting pregnant, but you should always speak to your specialist, who can explain the benefits and risks.

Biologics are included in national guidance for severe asthma, and in Scotland the Scottish Medicines Consortium has set strict eligibility criteria. The Scottish guide notes that uptake varies across the country and that earlier estimates suggested about 20% of eligible people with severe asthma in the UK received a biologic. Asthma + Lung UK advises that you will need referral to specialist care to work out if they are right for you.

These are NHS-funded treatments delivered through specialist centres. Private asthma clinics may offer assessments, but starting a biologic still relies on meeting criteria and having follow-up, so it is worth asking how reviews and funding would continue.