Belimumab can cause certain side effects, although many of these are mild. The most common side effects include headache, fever, diarrhea, nausea, muscle aches, trouble sleeping, and infections, such as colds, bronchitis, and urinary tract infections. You may also experience redness, itching, or swelling at the site of your injection.
Having fluid and/or a needle put into your veins (infusion) can also cause fevers, muscle aches, headaches, and infections.
Belimumab can lower the number of white blood cells in the blood of some people. It can also cause you to feel down and have thoughts of harming yourself, especially if you have a history of depression.
To know if belimumab is causing side effects, keep track of how long the symptoms last and whether they come back after your next infusion or injection. If so, discuss this with your rheumatology provider.