An IL-6 inhibitor biologic
Sarilumab
A biologic injection that blocks interleukin-6 to control rheumatoid arthritis.
What is Sarilumab?
Sarilumab is a biologic medicine used for rheumatoid arthritis. It blocks interleukin-6 (IL-6), a messenger that drives inflammation, which reduces joint pain, swelling and damage over time. It is given as an injection under the skin, which you can usually do at home after training. Because it dampens the immune system it raises the risk of infections and needs regular blood tests; you should be screened for infections such as TB and hepatitis before starting.
Education and reference only. This is a plain-language guide to Sarilumab — 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
Sarilumab is a biologic medicine, a laboratory-made antibody, used to treat rheumatoid arthritis when other treatments have not worked well enough. It works on the immune system to reduce the harmful inflammation that causes painful, swollen joints. It is given as an injection under the skin, usually self-administered at home after training, often alongside another arthritis tablet such as methotrexate or on its own.
How it works
Sarilumab blocks interleukin-6 (IL-6), one of the immune system's messengers that drives inflammation. In rheumatoid arthritis, excess IL-6 activity leads to joint pain, swelling and, over time, joint damage. By blocking IL-6, sarilumab calms this inflammation, easing symptoms and helping protect the joints. Because IL-6 also helps the body fight infection and shapes normal blood responses, blocking it can lower defences and affect blood tests.
Company & origin
Originated / developed by: Sanofi.
A biologic medicine used in the UK for rheumatoid arthritis, which works by blocking an immune messenger called interleukin-6.
What it treats
Conditions Sarilumab is used for
Practical use
How to take Sarilumab
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given as an injection under the skin, which you or a carer can usually do at home after training.
- Attend your regular blood tests, as these check your blood cells, liver and cholesterol while on treatment.
- Report any signs of infection, such as fever, sore throat or feeling generally unwell, without delay.
- Seek urgent advice for severe or lasting stomach pain, particularly with fever, as a bowel problem needs prompt assessment.
- Tell any healthcare professional you are on sarilumab, and avoid live vaccines unless your specialist agrees.
Weighing it up
Advantages & disadvantages of Sarilumab
Advantages
- Effectively reduces joint pain, swelling and stiffness in rheumatoid arthritis and can slow joint damage.
- Given as an injection under the skin that can be done at home.
- Can be used alongside methotrexate or on its own when methotrexate is not suitable.
Disadvantages
- Increases the risk of infections, including serious ones.
- Needs regular blood tests because it can affect blood cells, the liver and cholesterol.
- Carries a rare risk of bowel perforation, especially in people with a history of diverticulitis.
Practical use
Good to know
Sarilumab is a specialist medicine that needs careful safety checks, much like other IL-6 blockers. Because it lowers the immune response, it raises the risk of infections, including serious ones, so you will be screened for infections such as tuberculosis and hepatitis before starting and asked to report infection signs promptly. It can lower your white blood cell and platelet counts, raise your cholesterol and affect your liver, so regular blood tests are part of treatment. There is a rare but serious risk of a tear in the bowel (perforation), more likely in people who have had diverticulitis, so report severe or persistent stomach pain, especially with fever or a change in bowel habit. It can mask a fever, so look for other infection signs. Live vaccines are generally avoided while on it.
Who should not take it / use with caution
- People with an active serious infection, including untreated tuberculosis, should not start until it is treated.
- It is used with great caution in people with a history of diverticulitis or bowel problems.
- People with very low white cell or platelet counts, or significant liver problems, may not be suitable until reviewed.
Monitoring
- Screening for tuberculosis and hepatitis before starting, and watching for infection throughout.
- Regular blood tests for white cells, platelets, liver function and cholesterol.
- Reviewing joint symptoms and disease activity to judge how well it is working.
Side effects
- Increased infections, such as chest or urine infections, and cold sores.
- Raised cholesterol, changes in liver tests, and lower white cell or platelet counts seen on blood tests.
- Injection-site reactions; rarely, serious infections or bowel perforation.
Key interactions
- Avoid live vaccines while on treatment, as the immune response may be affected.
- It can change how the body handles some other medicines, so doses of certain drugs may need review.
- Combining it with other strong immune-suppressing biologics is generally avoided to limit infection risk.
Available as: Injection under the skin (prefilled pen or syringe).
Answers
Sarilumab: frequently asked questions
How is sarilumab different from tocilizumab?
Both block the IL-6 pathway for rheumatoid arthritis and have similar benefits and cautions; sarilumab is given as an injection under the skin, and your specialist chooses based on your situation.
Why do I need regular blood tests?
It can lower your white cells and platelets, raise your cholesterol and affect your liver, so blood tests check that everything stays safe during treatment.
Does it increase infections?
Yes. By calming the immune system it can increase infections, including serious ones, so you are screened beforehand and should report infection signs promptly.
Why does stomach pain matter on sarilumab?
There is a rare risk of a tear in the bowel, more likely if you have had diverticulitis, so severe or lasting stomach pain, especially with fever, needs urgent assessment.
Can I have it with methotrexate?
Yes, it is often used alongside methotrexate, but it can also be used on its own if methotrexate is not suitable for you.
Authoritative sources
- BNF
- NICE CKS
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