What is belimumab?

Belimumab (trade name: Benlysta) is a type of drug called a biological therapy. In lupus, B-cells in the body produce harmful autoantibodies which attack the body’s own tissues. Belimumab works by reducing the number of B-cells to reduce inflammation and improve your symptoms. It’s a long-term treatment, so it may be up to six months before you start to notice the benefits. Belimumab can be prescribed by a consultant rheumatologist for adults with lupus. It can be taken with other treatments for lupus.

Belimumab won’t be started if:

  • your lupus isn’t active
  • you haven’t tried other treatments appropriate for your condition first.

Your doctor may decide not to prescribe belimumab if you’re pregnant or breastfeeding, or if

  • you have, or have recently had, an infection
  • your lupus affects your kidneys or nervous system
  • you have HIV
  • your B-cell or antibody levels are low
  • you’ve had hepatitis
  • you have any kind of transplant
  • you’ve had cancer.

You’ll have blood tests to check your antibody and possibly your B-cell levels before treatment and every few months afterwards. Your doctor may also check for previous hepatitis infection as belimumab may increase the risk of hepatitis being reactivated.

How is it taken?

Belimumab is given through a drip into a vein (intravenous infusion) in hospital, and it usually takes about an hour. The first three infusions will be two weeks apart, and after that they will be given monthly. You may be offered anti-histamines and paracetamol to reduce the chance of a reaction to the infusion.

If you haven’t noticed any improvement in your symptoms after six months, discuss it with your doctor, who may decide to discontinue the treatment.

Because it’s a long-term treatment, it’s important to keep taking belimumab (unless you have severe side-effects):

  • even if it doesn’t seem to be working at first
  • even when your symptoms improve (to help keep the disease under control).

Side-effects and risks

Some people may feel sick, have a high temperature or diarrhoea during infusions. If this happens, tell your health team as they may be able to reduce these effects. A few people have side-effects between five and ten days after the infusion, including:

  • diarrhoea or feeling sick
  • fever
  • headaches or facial swelling
  • muscle pains
  • tiredness or difficulty sleeping
  • depression.

Because belimumab affects your immune system, you may be more likely to pick up infections. Tell your doctor about these or any other unexplained side-effects, particularly any that may indicate an infection.

Some people have an allergic reaction with sudden swelling, a rash or breathlessness. This is very rare, but if you do develop these symptoms, or any other severe symptoms while taking belimumab, you should seek medical advice immediately.

Also in very rare cases, patients treated with belimumab have developed a serious condition called progressive multifocal leukoencephalopathy (PML), which can damage the brain and spinal cord. You must see your doctor immediately if you notice any of the following:

  • problems with thinking or memory
  • difficulty walking
  • speech problems
  • loss of vision.

Reducing the risk of infection

Effects on other treatment

Belimumab may be prescribed alongside other drug treatments for lupus, but may interact badly with some other medicines. Check with your doctor before starting any new medicines, and remember to mention you’re on belimumab if you’re treated by anyone other than your usual rheumatology team.

Don’t take over-the-counter or herbal medicines without discussing this first with your healthcare team.

It’s recommended that you carry a biological therapy alert card. Then anyone treating you will know that you’ve had belimumab and that your antibody levels may be low. Ask your rheumatology team for a card.


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

It’s usually recommended that live vaccines such as yellow fever and shingles should be avoided during and for 30 days before starting treatment with belimumab. However, sometimes a live vaccine may be necessary – for example, rubella immunisation in women of childbearing age.

Pneumococcal vaccine, which protects against the most common cause of pneumonia, and yearly flu vaccines are safe and recommended.

Having an operation

If you’re planning to have an operation, talk this over with your specialists. You may be advised to stop belimumab for a time before and after your surgery.


You can drink alcohol while on belimumab but keep within the recommended limits for adults of no more than 14 units per week – unless your doctor advises a lower limit.

Fertility, pregnancy and breastfeeding

There’s limited information available about the effects of belimumab in pregnancy. Women who could become pregnant should use effective contraception while being treated with belimumab and for four months after stopping treatment.

It is not yet known whether belimumab passes into human breastmilk so you should talk to your rheumatology team if you’re thinking of breastfeeding.

There is currently no information available on the possible effects of belimumab on male and female fertility.