This medication is used with other medications to treat certain types of lupus. Belimumab belongs to a class of drugs known as monoclonal antibodies. It works by decreasing the effect of a certain protein that is increased in people with active lupus. This may help decrease some of the symptoms of lupus.

Read the Medication Guide provided by your pharmacist before you start using belimumab and each time you get a treatment. If you have any questions, ask your doctor or pharmacist.

This medication is given by injection into a vein over 1 hour by a health care professional. It is given as directed by your doctor, usually every 2 weeks for the first 3 doses, then every 4 weeks thereafter. The dosage is based on your weight.

Infusion reactions may happen during or after the infusion of this drug. Your doctor may prescribe other medications before each treatment to help prevent these side effects. Tell your doctor right away if you have any symptoms of infusion reactions such as headache, slow heartbeat, muscle pain, dizziness/fainting, or nausea. Your doctor may give you other medications to help with these side effects or may slow down or stop your treatment for some time.

Use this medication regularly to get the most benefit from it. To help you remember, mark your calendar with a reminder.

Tell your doctor if your condition does not get better or if it gets worse.

See also How to Use section.

Nausea, diarrhea, or trouble sleeping may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor 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)

This medication may lower your ability to fight infections. This may make you more likely to get a serious (rarely fatal) infection or make any infection you have worse. Tell your doctor right away if you have any signs of infection (such as sore throat that doesn't go away, fever, chills, cough).

Very rarely, people using this medication have developed cancers (including skin cancer). Tell your doctor right away if you develop symptoms such as a new skin lesion or bump, change in size or color of a mole, night sweats, swollen glands, or unexplained weight loss.

This medication may increase your risk of getting a rare but very serious (possibly fatal) brain infection (progressive multifocal leukoencephalopathy-PML). Get medical help right away if you have any of these side effects:

• clumsiness
• loss of coordination/balance
• weakness
• sudden change in your thinking (such as confusion, difficulty concentrating, memory loss)
• difficulty talking/walking
• seizure
• vision changes

Get medical help right away if you have any very serious side effects, including:

• heart problems (such as chest/jaw/left arm pain, shortness of breath, unusual sweating)

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.

Before using belimumab, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• infections (current infections, infections that return)
• mental/mood problems (such as depression, thoughts of suicide)
• cancer

Belimumab can make you more likely to get infections or may make current infections worse. Stay away from anyone who has an infection that may easily spread (such as chickenpox, COVID-19, measles, flu). Talk to your doctor if you have been exposed to an infection or for more details.

Tell your doctor your vaccine history and ask if you need to get any vaccines before starting treatment with this medication. Tell your health care professional that you are using belimumab before having any immunizations/vaccinations. Avoid contact with people who have recently received live vaccines (such as flu vaccine inhaled through the nose).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

This drug passes into breast milk. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug include:

• other drugs that weaken the immune system/increase the risk of infection (such as natalizumab, rituximab)

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669.

Lab and/or medical tests may be done while you are using this medication. Keep all medical and lab appointments. Consult your doctor for more details.

It is important to get each dose of this medication as scheduled. If you miss a dose, ask your doctor or pharmacist right away for a new dosing schedule.

Not applicable. This medication is given in a clinic and will not be stored at home.

Your condition can cause complications in a medical emergency. For information about enrolling in MedicAlert, call 1-888-633-4298 (US) or 1-800-668-1507 (Canada).