What is Belimumab: Uses, Dosage, Side Effects and More

Belimumab is a prescription medication that helps calm your overactive immune system when it mistakenly attacks your own body. It's specifically designed to treat autoimmune conditions like lupus, where your immune system needs gentle guidance to stop fighting against you.

This medication works by blocking a protein called BLyS (B-lymphocyte stimulator) that tells certain immune cells to become overactive. Think of it as turning down the volume on an immune system that's been playing too loudly.

What is Belimumab Used For?

Belimumab is primarily used to treat systemic lupus erythematosus (SLE), commonly known as lupus. Your doctor might prescribe it when you have active lupus that hasn't responded well enough to standard treatments like antimalarials, corticosteroids, or immunosuppressants.

The medication is also approved for treating lupus nephritis, which happens when lupus affects your kidneys. This is a more serious form of lupus that needs careful management to protect your kidney function.

Additionally, belimumab can help with active systemic lupus erythematosus in children aged 5 years and older. Your doctor will carefully weigh the benefits and risks before recommending it for younger patients.

How Does Belimumab Work?

Belimumab works by targeting B-cells, which are immune cells that produce antibodies. In lupus, these B-cells become overactive and create antibodies that attack your own healthy tissues instead of protecting you from infections.

The medication blocks BLyS, a protein that acts like fuel for these overactive B-cells. By reducing this fuel source, belimumab helps decrease the number of problematic B-cells in your system, which can reduce lupus symptoms and flares.

This is considered a targeted therapy rather than a broad immunosuppressant, meaning it's more precise in how it affects your immune system. However, it's still a strong medication that requires careful monitoring by your healthcare team.

How Should I Take Belimumab?

Belimumab comes in two forms: intravenous (IV) infusion and subcutaneous (under-the-skin) injection. Your doctor will determine which form is best for you based on your specific condition and lifestyle needs.

For IV infusions, you'll receive the medication at a healthcare facility every four weeks. The infusion typically takes about one hour, and you'll be monitored during and after the treatment for any immediate reactions.

If you're using the subcutaneous form, you'll likely inject it once weekly at home after proper training. Your healthcare team will teach you the correct injection technique and help you feel comfortable with the process.

You don't need to take belimumab with food, but it's important to maintain a consistent schedule. Some people find it helpful to mark their calendar or set phone reminders to stay on track.

How Long Should I Take Belimumab For?

Belimumab is typically a long-term treatment that you'll continue as long as it's helping your lupus and you're tolerating it well. Many people take it for years to maintain control of their symptoms and prevent flares.

You might start noticing improvements after a few months, though it can take up to six months to see the full benefits. This gradual improvement happens because belimumab works by slowly reducing the overactive immune cells rather than providing immediate relief.

Your doctor will regularly assess how well the medication is working through blood tests, symptom monitoring, and checking for any side effects. They'll help you decide when it's appropriate to continue, adjust, or potentially stop the treatment.

What Are the Side Effects of Belimumab?

Like all medications that affect your immune system, belimumab can cause side effects, though not everyone experiences them. Being aware of what to watch for helps you stay safe and get prompt care if needed.

The most common side effects you might experience include nausea, diarrhea, fever, stuffy nose, bronchitis, insomnia, and pain in your arms or legs. These symptoms are usually mild and often improve as your body adjusts to the medication.

More serious but less common side effects can include:

• Increased risk of infections due to immune system suppression
• Severe allergic reactions, especially during IV infusions
• Depression or mood changes
• Serious infections that may require hospitalization

Because belimumab affects your immune system, you'll have a higher risk of getting infections. This means you should contact your doctor if you develop fever, flu-like symptoms, or any signs of infection.

Rare but serious side effects include severe depression, thoughts of self-harm, progressive multifocal leukoencephalopathy (PML), and reactivation of hepatitis B in people who previously had this infection.

Who Should Not Take Belimumab?

Belimumab isn't right for everyone, and your doctor will carefully review your medical history before prescribing it. You shouldn't take this medication if you've had a severe allergic reaction to belimumab or any of its ingredients in the past.

People with active, severe infections should wait until the infection is fully treated before starting belimumab. This includes serious bacterial, viral, fungal, or other infections that could worsen with immune suppression.

Your doctor will be especially cautious if you have:

• A history of chronic infections or frequent infections
• HIV, hepatitis B, or hepatitis C
• A history of depression or suicidal thoughts
• Previous cancer or current cancer treatment
• Plans to receive live vaccines

If you're pregnant or planning to become pregnant, you'll need to discuss the risks and benefits with your doctor. Belimumab can cross the placenta and potentially affect your developing baby's immune system.

Belimumab Brand Names

Belimumab is available under the brand name Benlysta. This is the only brand name currently available for this medication, manufactured by GSK (GlaxoSmithKline).

Whether you receive the IV or subcutaneous form, both are marketed under the same Benlysta brand name. Your prescription will specify which formulation and strength you need.

Belimumab Alternatives

If belimumab isn't suitable for you or isn't providing adequate control of your lupus, several alternative treatments are available. Your doctor might consider other biologic medications like rituximab, which also targets B-cells but works differently.

Traditional immunosuppressive medications remain important options, including methotrexate, mycophenolate, azathioprine, and cyclophosphamide. These medications have longer track records and may be more appropriate for certain situations.

Newer treatments like anifrolumab (Saphnelo) offer another targeted approach for lupus treatment. Your doctor will consider factors like your specific symptoms, previous treatments, and overall health when selecting the best option for you.

Sometimes, combination therapy with antimalarials like hydroxychloroquine or careful corticosteroid management might be more appropriate than switching to a different biologic medication.

Is Belimumab Better Than Rituximab?

Comparing belimumab to rituximab isn't straightforward because they work differently and are used in different situations. Both target B-cells, but rituximab depletes these cells more completely while belimumab reduces their activation more gradually.

Belimumab has more robust clinical trial data specifically for lupus treatment, with FDA approval based on large, well-designed studies. Rituximab, while effective for many lupus patients, is used "off-label" for this condition.

The choice between these medications depends on your specific situation, including how severe your lupus is, which organs are affected, and how you've responded to previous treatments. Your doctor will consider your individual factors rather than declaring one universally "better."

Some people do well with belimumab's gentler, sustained approach, while others need rituximab's more dramatic B-cell depletion. Both medications require careful monitoring and have their own unique side effect profiles.