Benlysta (Belimumab)
Monoclonal antibody for systemic lupus erythematosus (SLE) and lupus nephritis
Benlysta (belimumab) is a biologic medicine used to treat systemic lupus erythematosus (SLE) and lupus nephritis. It works by blocking a protein called BLyS (B-lymphocyte stimulator), which helps reduce the overactive immune response that causes lupus symptoms. Benlysta is given as a subcutaneous injection and is always used alongside other lupus medications.
Quick Facts
Key Takeaways
- Benlysta is the first biologic therapy specifically approved for systemic lupus erythematosus, targeting the BLyS protein to reduce B-cell overactivity.
- It is administered as a weekly subcutaneous injection (200 mg) for adults and is approved for children aged 5 years and older with active SLE.
- Common side effects include infections (urinary and respiratory tract), injection site reactions, nausea, and diarrhea. Serious risks include depression, suicidal ideation, and severe allergic reactions.
- Benlysta must always be used in combination with standard lupus therapy, not as a standalone treatment.
- Store refrigerated at 2–8°C. A pre-filled pen may be kept at room temperature for up to 12 hours before use.
What Is Benlysta and What Is It Used For?
Benlysta contains the active substance belimumab, a fully human monoclonal antibody that targets and inhibits the soluble form of B-lymphocyte stimulator (BLyS), also known as B-cell activating factor (BAFF). BLyS is a naturally occurring protein in the body that plays a crucial role in the survival and differentiation of B cells — a type of white blood cell that is central to the immune system.
In people with systemic lupus erythematosus (SLE), the immune system mistakenly attacks the body's own healthy cells and tissues. This autoimmune process involves overactive B cells that produce harmful autoantibodies, leading to chronic inflammation and damage to multiple organ systems including the skin, joints, kidneys, blood vessels, and the central nervous system. Patients with SLE typically have elevated levels of BLyS, which contributes to the survival of these autoreactive B cells.
By blocking BLyS, belimumab reduces the number of circulating B cells, including autoreactive B cells, without completely depleting the immune system. This targeted approach helps decrease disease activity while preserving some baseline immune function. Clinical trials have demonstrated that belimumab, when added to standard lupus therapy, significantly reduces disease flares, decreases the need for corticosteroids, and improves overall disease control.
Benlysta was first approved by the U.S. Food and Drug Administration (FDA) in 2011, making it the first new drug approved specifically for lupus in over 50 years. It has since received regulatory approval in the European Union, Japan, and many other countries worldwide, representing a landmark advance in the management of SLE.
Approved Indications
Benlysta as a subcutaneous injection is approved for the following indications:
- Systemic Lupus Erythematosus (SLE) in adults (18 years and older): For patients whose disease remains highly active despite standard treatment with corticosteroids, antimalarials, immunosuppressants, or non-steroidal anti-inflammatory drugs (NSAIDs).
- SLE in children and adolescents (5 to 17 years, weighing at least 15 kg): For pediatric patients with active SLE despite standard therapy.
- Active lupus nephritis in adults (18 years and older): Used in combination with immunosuppressive therapies for kidney inflammation caused by lupus.
Benlysta does not replace your existing lupus medications. It is designed to be used in combination with your current standard treatment regimen, such as corticosteroids, hydroxychloroquine, azathioprine, or mycophenolate mofetil. Your doctor will determine the most appropriate combination for your individual situation.
How Does Benlysta Work?
The mechanism of action of belimumab is based on its ability to selectively bind to soluble BLyS and prevent it from interacting with its receptors on B cells. This process has several important downstream effects:
- Reduced B-cell survival: Without BLyS signaling, fewer B cells survive and mature, leading to a gradual reduction in the number of circulating B cells over weeks to months.
- Decreased autoantibody production: Fewer autoreactive B cells means reduced production of the harmful antibodies (such as anti-dsDNA antibodies) that drive lupus inflammation.
- Lower disease activity: The overall reduction in autoimmune activity leads to fewer disease flares, less organ damage, and improved quality of life.
Unlike some other B-cell-targeting therapies, belimumab does not directly destroy existing B cells or plasma cells. Instead, it prevents the formation and survival of new autoreactive B cells, which is why its therapeutic effects develop gradually over several weeks of treatment.
What Should You Know Before Taking Benlysta?
Contraindications
You must not use Benlysta if you are allergic (hypersensitive) to belimumab or to any of the other ingredients in this medicine. Ingredients include arginine hydrochloride, histidine, histidine monohydrochloride, polysorbate 80, sodium chloride, and water for injections. If you have a known allergy to polysorbate 80, inform your doctor before starting treatment.
Benlysta has not been studied and is therefore not recommended in patients with severe active central nervous system lupus or in patients with severe active lupus nephritis requiring urgent aggressive immunosuppressive therapy (such as dialysis or high-dose cyclophosphamide).
Warnings and Precautions
Before starting Benlysta, have an open discussion with your doctor about your complete medical history. The following situations require special attention:
- Current or chronic infections: If you have an ongoing infection or a history of frequent infections, your doctor will assess whether it is safe to start belimumab. Benlysta can weaken parts of the immune system and may increase susceptibility to infections.
- Vaccinations: Certain types of vaccines (live vaccines) should not be given shortly before or during treatment with Benlysta. If you have been vaccinated within the last 30 days or plan to be vaccinated, discuss this with your doctor. Inactivated vaccines can generally be given, but the immune response may be reduced.
- Neurological lupus: If your lupus affects your nervous system, additional monitoring may be required.
- HIV or low immunoglobulin levels: Benlysta has not been studied in patients with HIV infection or those with very low immunoglobulin levels, and is generally not recommended in these populations.
- Hepatitis B or C: If you have or have had hepatitis B or C, inform your doctor as Benlysta may affect the immune response to these infections.
- Organ or stem cell transplant: Patients who have received an organ transplant, bone marrow transplant, or stem cell transplant have not been studied with Benlysta.
- History of cancer: The safety of Benlysta in patients with a history of malignancy has not been fully evaluated.
- Previous severe skin reactions to Benlysta: If you have ever developed severe rashes, blistering, or mouth sores after using Benlysta, do not use it again.
Depression, suicidal thoughts, and suicide attempts — including completed suicide — have been reported during treatment with Benlysta. If you have a history of depression or mental health conditions, discuss this with your doctor before starting treatment. During treatment, contact your doctor immediately or seek emergency help if you experience new or worsening feelings of depression, hopelessness, or thoughts of self-harm. Consider telling a family member or close friend about your treatment so they can help watch for changes in your mood or behavior.
Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) have been reported in connection with Benlysta treatment. Stop using Benlysta and seek immediate emergency medical attention if you develop reddish target-like or circular patches on the trunk, blistering, peeling skin, or sores in the mouth, throat, nose, genitals, or eyes. These serious skin reactions may be preceded by fever and flu-like symptoms.
Pregnancy and Breastfeeding
Benlysta is generally not recommended during pregnancy. Animal studies have shown effects on the developing fetus, including reduced B-cell numbers. If you are pregnant, think you may be pregnant, or are planning to become pregnant, talk to your doctor before using Benlysta. Your doctor will weigh the potential benefits against the risks.
Contraception: Women of childbearing potential must use effective contraception during treatment with Benlysta and for at least 4 months after the last dose. This is because belimumab may remain in the body for some time after treatment ends.
Breastfeeding: It is likely that Benlysta can pass into breast milk. Discuss with your doctor whether to discontinue Benlysta during breastfeeding or to stop breastfeeding while on treatment.
Driving and Operating Machinery
Benlysta may cause side effects such as fatigue, dizziness, or other symptoms that could impair your ability to drive or use machines safely. If you experience any such effects, do not drive or operate machinery until you feel well enough to do so.
Children and Adolescents
Benlysta subcutaneous injection (pre-filled pen) is approved for children and adolescents aged 5 to 17 years who weigh at least 15 kg for the treatment of SLE. The dosing frequency is adjusted according to body weight. However, Benlysta subcutaneous injection is not approved for children or adolescents under 18 years for the treatment of lupus nephritis. For children under 10 years, the injection must be administered by a healthcare professional or a trained caregiver.
How Does Benlysta Interact with Other Drugs?
Because Benlysta works by suppressing part of the immune system, combining it with other immunosuppressive medications can increase the overall degree of immune suppression and raise the risk of serious infections. It is essential to tell your doctor about all medicines you are currently taking, have recently taken, or might take.
While Benlysta is routinely used alongside standard lupus therapies such as hydroxychloroquine, corticosteroids, azathioprine, and mycophenolate mofetil, certain drug combinations require particular caution or are contraindicated.
Major Interactions
| Interacting Drug | Interaction Type | Clinical Significance | Recommendation |
|---|---|---|---|
| Rituximab (and other anti-CD20 agents) | Additive B-cell depletion | Greatly increased risk of severe infections and profound immunosuppression | Avoid combination; not studied together |
| Cyclophosphamide (IV) | Additive immunosuppression | Increased risk of serious and opportunistic infections | Not recommended in combination |
| Other biologic immunosuppressants | Additive immunosuppression | Compounded immune system suppression | Avoid; clinical data insufficient |
| Live vaccines (e.g., MMR, varicella, yellow fever) | Reduced immune response / risk of vaccine-strain infection | Vaccines may be ineffective or cause active infection | Avoid live vaccines during treatment; administer 30 days before starting Benlysta if needed |
Minor Interactions
Benlysta is commonly used together with the following standard lupus medications, and no clinically significant pharmacokinetic interactions have been identified:
- Hydroxychloroquine: Safe to combine; no dose adjustment needed.
- Oral corticosteroids (e.g., prednisolone): Safe to combine; Benlysta may allow gradual corticosteroid dose reduction over time.
- Azathioprine: Safe to combine; monitor blood counts as both can cause leukopenia.
- Mycophenolate mofetil: Safe to combine; monitor for signs of infection.
- NSAIDs: No known interaction with belimumab.
Inactivated (non-live) vaccines, such as influenza or pneumococcal vaccines, can be given during Benlysta treatment. However, the immune response to vaccination may be somewhat reduced. Your doctor may recommend checking antibody levels after vaccination to ensure adequate protection.
What Is the Correct Dosage of Benlysta?
Benlysta must always be used exactly as prescribed by your doctor or pharmacist. The subcutaneous injection is administered under the skin of the abdomen (stomach area) or thigh. Do not inject into a vein (intravenously). The dosing schedule varies depending on the indication and patient age and weight.
Adults — Systemic Lupus Erythematosus
Standard SLE Dosage
The recommended dose is 200 mg (the full contents of one pre-filled pen) given as a subcutaneous injection once weekly.
Adults — Lupus Nephritis
Lupus Nephritis Dosage
Your doctor will prescribe the appropriate dose for your situation. The options are:
- Option A: 200 mg (one pre-filled pen) once weekly from the start of treatment.
- Option B: 400 mg (two pre-filled pens on the same day) once weekly for the first 4 weeks, followed by 200 mg (one pre-filled pen) once weekly thereafter.
Children and Adolescents (5–17 years)
The recommended dose for children and adolescents with SLE depends on body weight:
| Body Weight | Dose | Frequency |
|---|---|---|
| 50 kg or more | 200 mg (1 pre-filled pen) | Once weekly |
| 30 kg to under 50 kg | 200 mg (1 pre-filled pen) | Every 10 days |
| 15 kg to under 30 kg | 200 mg (1 pre-filled pen) | Every 2 weeks |
Benlysta subcutaneous injection is not approved for children or adolescents under 18 years for the treatment of lupus nephritis.
How to Self-Inject
Your doctor or nurse will show you (or your caregiver) how to inject Benlysta using the pre-filled pen. They will supervise your first self-injection. After you have been trained in the correct injection technique, your doctor or nurse may allow you to inject at home. Key steps include:
- Remove the pre-filled pen from the refrigerator and let it reach room temperature for 30 minutes before injection. Do not warm it by any other means (e.g., microwave, hot water, or direct sunlight).
- Inspect the solution through the viewing window — it should be colorless to slightly yellow and free of particles. It is normal to see air bubbles.
- Choose an injection site on the abdomen or thigh. Do not inject within 5 cm of the navel. Rotate injection sites to prevent skin hardening.
- Clean the injection site with an alcohol swab and let it air dry.
- Remove the cap immediately before injection. Place the pen at a 90° angle to the skin and press firmly. The injection takes up to 15 seconds to complete.
- Dispose of the used pen in a sharps container. Do not replace the cap.
If you need two injections for your full dose (e.g., 400 mg), the injections should be given at least 5 cm apart if using the same body area.
Missed Dose
If you forget a dose, inject it as soon as you remember. Then continue with your regular weekly schedule, or start a new weekly schedule from the day you injected the missed dose. If you do not realize you have missed a dose until it is time for your next scheduled injection, simply give the next dose as planned. Do not double up doses to make up for a missed one.
Overdose
If you accidentally use more Benlysta than prescribed, contact your doctor or nurse immediately. They will monitor you for any signs or symptoms of adverse effects and provide treatment as needed. If possible, bring the packaging or this information with you. There is no specific antidote for belimumab overdose; treatment is supportive and symptomatic.
Changing Your Dosing Day
If you wish to change your injection day, simply take a dose on the new day (even if it has been fewer days than usual since your last dose). Continue with the new schedule from that day forward.
Stopping Treatment
Do not stop using Benlysta without first talking to your doctor. Your doctor will decide if you need to stop treatment and will advise on the best approach for discontinuation.
What Are the Side Effects of Benlysta?
Like all medicines, Benlysta can cause side effects, although not everyone experiences them. The safety profile of belimumab has been established through extensive clinical trials involving thousands of patients, including the pivotal BLISS-52, BLISS-76, and BLISS-LN studies. Understanding the frequency and nature of potential side effects helps you and your doctor make informed treatment decisions and know when to seek medical attention.
Very Common
- Bacterial infections
- Urinary tract infections
- Upper respiratory tract infections (cold, sinusitis, bronchitis)
Common
- Fever (elevated temperature)
- Injection site reactions (rash, redness, itching, swelling)
- Hives (urticaria) and rash
- Low white blood cell count (leukopenia)
- Infection of the nose, throat, or stomach (nasopharyngitis, gastroenteritis)
- Pain in hands or feet
- Migraine
- Nausea
- Diarrhea
- Depression
Uncommon
- Severe allergic (anaphylactic) reactions
- Suicidal thoughts or suicide attempts
- Angioedema (swelling of face, lips, or throat)
Frequency Not Known
- Stevens-Johnson syndrome (SJS)
- Toxic epidermal necrolysis (TEN)
Allergic Reactions
Benlysta can cause injection reactions or allergic (hypersensitivity) reactions. These reactions are common (affecting up to 1 in 10 patients) but are usually mild. However, severe reactions are uncommon (up to 1 in 100 patients) and can be life-threatening. Serious allergic reactions are more likely to occur on the day of the first or second treatment but may be delayed and appear several days later.
Seek immediate medical attention if you experience any of the following:
- Swelling of the face, lips, mouth, or tongue
- Wheezing, difficulty breathing, or shortness of breath
- Widespread rash or hives
- Itchy, raised bumps on the skin
In rare cases, delayed reactions may occur, typically 5 to 10 days after an injection. These can include a combination of rash, feeling unwell, fatigue, muscle pain, headache, and facial swelling. Report any such symptoms to your doctor promptly.
Infections
Benlysta may increase the risk of infections, including infections of the urinary tract and respiratory tract. These are very common and may affect more than 1 in 10 patients. Some infections can be serious and may, in rare cases, be fatal. The risk of infections may be higher during the initial months of treatment and in patients who are also taking other immunosuppressive medications.
Contact your doctor immediately if you experience:
- Fever and/or chills
- Cough or breathing difficulties
- Diarrhea or vomiting
- Burning sensation during urination or frequent need to urinate
- Warm, red, or painful skin, or sores on the body
Depression and Mental Health
Depression, suicidal thoughts, and suicide attempts have been reported during treatment with Benlysta. Depression may affect up to 1 in 10 patients. Suicidal thoughts and suicide attempts may affect up to 1 in 100 patients. It is important to note that depression is also common in people with lupus itself, so it may be difficult to determine whether symptoms are related to the disease or the medication. Regardless of the cause, any new or worsening mood changes should be reported to your doctor immediately.
Medicines that weaken the immune system, including Benlysta, may increase the risk of a rare but serious brain infection called progressive multifocal leukoencephalopathy (PML), caused by the JC virus. Symptoms of PML include memory loss, difficulty thinking, difficulty speaking or walking, and vision loss. Tell your doctor immediately if you develop any of these symptoms or notice any changes in symptoms you had before starting Benlysta. PML can be fatal if not detected early. There is no specific treatment for PML; management typically involves stopping immunosuppressive therapy to allow the immune system to fight the infection.
How Should You Store Benlysta?
Proper storage of Benlysta is essential to ensure the medicine remains effective and safe to use. Biologic medicines like belimumab are sensitive to temperature and light, and improper storage can degrade the active ingredient, reducing efficacy or potentially causing adverse reactions.
- Refrigerate: Store at 2°C to 8°C (36°F to 46°F).
- Do not freeze. If the pre-filled pen has been frozen, do not use it even if it has thawed.
- Protect from light: Keep in the original carton until ready for use.
- Room temperature: A pre-filled pen can be stored at room temperature (up to 25°C / 77°F) for a maximum of 12 hours, provided it is kept protected from light.
- After removal from refrigerator: The pen must be used within 12 hours or discarded. Do not return it to the refrigerator.
- Keep out of reach of children.
- Check expiry date: Do not use after the expiration date printed on the label and carton (EXP). The expiration date refers to the last day of that month.
- Do not use damaged pens: If the pre-filled pen has been dropped on a hard surface, do not use it.
Do not dispose of medicines in wastewater or household waste. Ask your pharmacist how to properly dispose of medicines you no longer use. This helps protect the environment.
What Does Benlysta Contain?
Active Ingredient
The active substance is belimumab. Each 1 mL pre-filled pen contains 200 mg of belimumab.
Inactive Ingredients (Excipients)
| Ingredient | Function |
|---|---|
| Arginine hydrochloride | Stabilizer |
| Histidine | Buffer (pH control) |
| Histidine monohydrochloride | Buffer (pH control) |
| Polysorbate 80 (E 433) | Surfactant / stabilizer |
| Sodium chloride | Tonicity agent |
| Water for injections | Solvent |
This medicine contains 0.1 mg polysorbate 80 per pre-filled pen. Polysorbates may cause allergic reactions in sensitive individuals. Inform your doctor if you have known allergies to polysorbates. This medicine contains less than 1 mmol (23 mg) sodium per dose, meaning it is essentially sodium-free.
Appearance and Packaging
Benlysta is supplied as a colorless to slightly yellow solution in a single-use pre-filled pen containing 1 mL. It is normal to see one or more air bubbles in the solution. Do not use the pen if the solution appears cloudy, discolored, or contains visible particles.
Available pack sizes: 1 or 4 pre-filled pens per carton, and multipacks containing 12 pre-filled pens (3 cartons of 4 pens). Not all pack sizes may be marketed in your country.
Marketing Authorization Holder
GlaxoSmithKline (Ireland) Limited, 12 Riverwalk, Citywest Business Campus, Dublin 24, Ireland.
Frequently Asked Questions About Benlysta
Medical References and Sources
This article is based on current medical research, approved product information, and international guidelines. All claims are supported by scientific evidence from peer-reviewed sources.
- European Medicines Agency (EMA). "Benlysta (belimumab) – Summary of Product Characteristics." EMA EPAR – Benlysta European regulatory product information including approved indications, dosage, and safety data.
- U.S. Food and Drug Administration (FDA). "Benlysta (belimumab) – Prescribing Information." FDA Prescribing Information U.S. regulatory approved labeling with comprehensive drug information.
- Furie R, et al. (2011). "A phase III, randomized, placebo-controlled study of belimumab, a monoclonal antibody that inhibits B lymphocyte stimulator, in patients with systemic lupus erythematosus." Arthritis & Rheumatism. 63(12):3918–3930. doi:10.1002/art.30613 BLISS-76 pivotal clinical trial demonstrating efficacy of belimumab in SLE.
- Navarra SV, et al. (2011). "Efficacy and safety of belimumab in patients with active systemic lupus erythematosus: a randomised, placebo-controlled, phase 3 trial." The Lancet. 377(9767):721–731. doi:10.1016/S0140-6736(10)61354-2 BLISS-52 pivotal clinical trial confirming belimumab efficacy.
- Furie R, et al. (2020). "Two-year, randomized, controlled trial of belimumab in lupus nephritis." New England Journal of Medicine. 383(12):1117–1128. doi:10.1056/NEJMoa2001180 BLISS-LN trial supporting belimumab approval for lupus nephritis.
- Fanouriakis A, et al. (2023). "EULAR recommendations for the management of systemic lupus erythematosus: 2023 update." Annals of the Rheumatic Diseases. Annals of the Rheumatic Diseases European League Against Rheumatism guidelines for SLE management including biologics.
- American College of Rheumatology (ACR) (2024). "Guidelines for the Treatment of Lupus." ACR Guidelines American guidelines for lupus management including biologic therapy recommendations.
- World Health Organization (WHO). "Model List of Essential Medicines – 23rd List (2023)." WHO Essential Medicines WHO reference list for essential medicines and treatment standards.
Evidence grading: This article uses the GRADE framework (Grading of Recommendations Assessment, Development and Evaluation) for evidence-based medicine. Evidence level 1A represents the highest quality of evidence, based on systematic reviews of randomized controlled trials.
iMedic Medical Editorial Team
Specialists in rheumatology, immunology and internal medicine
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