See also How to Use section.
Nausea, diarrhea, or trouble sleeping may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Tell your doctor right away if you have any serious side effects, including: mental/mood changes (such as new/worsening depression, thoughts of suicide), signs of cancer (such as fever, night sweats, unusual tiredness, unexplained weight loss, swollen glands, unusual lumps/growths).
This medication can lower your body's ability to fight an infection. You may be more likely to get serious infections such as pneumonia, urinary tract infection, and skin infections. It may also be harder to fight an infection you already have. Tell your doctor right away if you develop signs of a serious infection while using this drug, such as: fever, chills, sore throat, cough, pain or burning with urination, urinating often, bloody diarrhea, coughing up mucus.
Belimumab may increase your risk of getting a rare but very serious (sometimes fatal) brain infection (progressive multifocal leukoencephalopathy-PML). Get medical help right away if you develop any signs of PML, including: confusion, memory loss, loss of balance, difficulty talking/walking, vision changes.
Get medical help right away if you have any serious side effects, including: heart problems (such as chest/jaw/left arm pain, shortness of breath, unusual sweating, dizziness).
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.