Bimekizumab

What is bimekizumab? 

Bimekizumab is a type of medicine known as a biological therapy. It is available under the brand name Bimzelx. Your healthcare team may give it to you if you have:  

Bimekizumab can also be used to treat severe psoriasis when other treatments have failed to work adequately.  

Studies have found that the interleukin proteins IL-17A and IL-17F can cause inflammation, pain and damage to parts of your body, such as your joints.  

Bimekizumab works by blocking the effects of these proteins, to reduce inflammation and the problems it can cause, such as joint pain, swelling and stiffness.  

Bimekizumab does not work immediately. It can take up to 6 months for the full benefit, but some improvement should be seen by 4 months. If bimekizumab is effective and you tolerate it well, it may be continued as a long-term treatment. 

Who can take bimekizumab?

There are guidelines about when bimekizumab can be used, depending on which condition you have.  

Bimekizumab won’t be started if: 

  •  your condition isn’t active  
  • you haven’t tried other treatments for your condition first  
  • you have an infection.  

Before you are started on bimekizumab, your healthcare team may use a scoring system to assess how active your condition is, and how it makes you feel.  

You may also need blood tests and a chest x-ray before treatment to make sure bimekizumab is safe for you to take. These tests may include tests for tuberculosis, hepatitis and HIV.  

If any of these tests are positive, your doctor may refer you to another specialist to decide on an appropriate treatment plan. If you have recently had other medicines that affect the immune system, you may well have had all these tests and may not necessarily need to have them repeated. 

Your doctor may also decide not to prescribe bimekizumab if: 

  • you have had repeated or serious infections in the past  
  • you have an inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis  
  • you are pregnant or planning to become pregnant 
  • you are having treatment with ultraviolet light for psoriasis, also known as phototherapy.  

Your doctor will discuss other treatment options with you if bimekizumab isn’t suitable. 

When and how do I take bimekizumab? 

Bimekizumab comes as an injection you inject under the skin. This is known as a subcutaneous injection. Most people inject under the skin of their thighs or stomach.   

You will need to take one 160 mg injection every 4 weeks.  

If you also have moderate or severe psoriasis, you may be given a different dose of one 320mg injection every 4 weeks for 5 doses and then one 320mg injection every 8 weeks after that 

Bimekizumab is available in a pre-filled syringe or a pen so that you, your partner, or another family member can learn to give you these injections at home. If you miss a dose or take one too soon, ask your healthcare team for advice on when to take your next dose.  

Because bimekizumab is a long-term treatment, it’s important to keep taking bimekizumab: 

  • even if it doesn’t seem to be working at first  
  • even when your symptoms start to improve.  

But if you have severe side effects or symptoms of an infection, tell your healthcare team. They may recommend that you delay or stop your treatment 

Side effects and risks

Most people don’t have any side effects with bimekizumab. For those who do, they are rarely serious.  

The most common side effects of bimekizumab are:  

  • cold and flu symptoms such as sore throat or stuffy nose  
  • fatigue 
  • headache.  

Some people may have a skin reaction at the injection site. This is usually mild and symptoms include redness, a rash, swelling, itching or bruising.  

Very rarely, some people may have a more severe allergic reaction. The symptoms of an allergic reaction include sudden swelling, a rash or breathlessness. If you develop these symptoms during or soon after a dose of bimekizumab, you should get medical advice immediately.  

Because bimekizumab affects your immune system, you may be more likely to pick up infections. If you have any symptoms of infection, or if you’re unsure, speak to your healthcare team immediately. They may recommend that you delay your next dose until you’re better.  

Some symptoms of an infection include: 

  • a fever  
  • feeling tired  
  • shortness of breath  
  • a constant cough  
  • diarrhoea  
  • burning when peeing.  

Bimekizumab may also cause fungal infections, such as athlete’s foot or genital or oral thrush. In most cases, these infections are mild. They can be treated using medicine and do not require you to stop bimekizumab.  

If you are concerned, you should speak to your healthcare team for advice. 

You should also speak to your healthcare team immediately if you develop chickenpox or shingles, or come into contact with someone who has chickenpox or shingles.  

These infections can be severe if you’re taking medicines that affect the immune system, such as bimekizumab. You may need antiviral treatment, and your bimekizumab treatment may be stopped until you’re better.  

Tips to reduce your risk of infection:  

  • Try to avoid close contact with people you know have an infection. 
  • Wash your hands regularly and carry around a small bottle of antibacterial hand gel.  
  • Keep your mouth clean by brushing your teeth regularly.  
  • Stop smoking if you’re a smoker. 
  • Make sure your food is stored and prepared properly.  
  • Try to keep your house clean and hygienic, especially the kitchen, bathrooms and toilets.  

Carrying an alert card

It’s recommended that you carry a biological therapy alert card so anyone treating you will know that you’re on bimekizumab. Ask your healthcare team for a card. 

Taking other medicines

Most medicines are safe to take with bimekizumab, however check with your doctor before starting any new medicines. Remember to mention you are taking bimekizumab if you are treated by anyone other than your usual healthcare team.  

Don’t use complementary treatments, such as herbal remedies, without discussing it first with your doctor or pharmacist, as some of them could react with bimekizumab. 

Vaccinations

It’s best to discuss vaccinations with your healthcare team before starting bimekizumab. 

It’s usually recommended that people taking bimekizumab avoid live vaccines, such as measles, mumps and rubella (MMR), chickenpox and yellow fever. However, sometimes a live vaccine may be needed, so this should be discussed with your healthcare team. 

If you need a live vaccine, it’s usually recommended that you have it at least 4 weeks before starting bimekizumab. 

Non-live vaccines are safe and recommended while taking bimekizumab. These include the annual flu vaccine, COVID-19 vaccines, the pneumococcal vaccine (Pneumovax) and the shingles vaccine (Shingrix). 

Having an operation or dental treatment

If you’re going to have an operation or dental treatment, you should talk this over with your doctor or surgeon. Depending on the type of surgery, your doctor may recommend that you stop bimekizumab for a while before and after the operation. This is because bimekizumab affects the immune system, which may increase your risk of infection after surgery. 

Alcohol 

There’s no need to avoid alcohol while taking bimekizumab.  

Guidelines state that adults shouldn’t have more than 14 units a week, and that they should spread them out over the course of the week. In some circumstances, your doctor may advise lower limits. 

Fertility, pregnancy and breastfeeding while taking bimekizumab

Bimekizumab is not usually recommended during pregnancy. Because bimekizumab is a relatively new drug, we do not yet know how it might affect pregnancy or an unborn baby. 

If you are considering becoming pregnant, you should discuss this with your healthcare team in advance. Tell your healthcare team immediately if you become pregnant while taking bimekizumab. 

In some circumstances, if your disease is severe and there are no suitable alternative treatments, your rheumatologist may advise you to continue bimekizumab during pregnancy. 

If bimekizumab is taken during the later stages of pregnancy, your baby should not have any live vaccines until they are 6 months old. 

There is limited information about bimekizumab and breastfeeding. Current guidance suggests that bimekizumab can be continued during breastfeeding, but you should discuss it first with your healthcare team. 

There is no evidence that bimekizumab affects male fertility, but research is limited. If you are concerned or would like more information, speak to your healthcare team. 

Related information

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Reviewers: Chris Holroyd, Mariam Malik and Sarah Bennett

Reviewed: May 2026

Next planned review: May 2029.