Siltuximab
Siltuximab is a monoclonal antibody that binds to interleukin-6 (IL-6), a signaling protein involved in immune responses. It is primarily used to treat multicentric Castleman disease, a rare condition where immune cells grow abnormally and produce excessive IL-6. By blocking IL-6 from binding to its receptors, siltuximab helps reduce inflammation and control symptoms associated with IL-6-driven disorders.
Siltuximab is an IL-6 inhibitor monoclonal antibody used to treat multicentric Castleman disease by blocking IL-6 signaling.
Key facts at a glance
- ATC
- L04AC11
- RxNorm
- 1535218
- Generic
- Siltuximab
- Class
- atc-l04
- Brands
- Sylvant
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- injection
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Siltuximab is FDA-approved for treating multicentric Castleman disease (MCD) in patients who are HIV-negative and human herpesvirus-8 (HHV-8)-negative. It may also be used in clinical settings for conditions associated with IL-6 overproduction.
Siltuximab is a chimeric monoclonal antibody that specifically binds to human IL-6, preventing it from attaching to both soluble and membrane-bound IL-6 receptors. This inhibition blocks IL-6-mediated signaling, which helps reduce the abnormal immune cell proliferation and inflammation seen in conditions like MCD.
Siltuximab is administered as an intravenous infusion. Common side effects may include rash, itching, upper respiratory tract infections, and infusion-related reactions. It should not be used in patients with severe infections. Patients should be monitored for infusion reactions and signs of infection during treatment. Live vaccines should be avoided during therapy.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 26, 2026. · Read our editorial policy