Rilonacept (Arcalyst)
What Is It?
Rilonacept (Arcalyst) is an anti-inflammatory medication used to treat a variety of inflammatory disorders. Rilonacept is FDA approved to treat recurrent pericarditis and the following autoinflammatory diseases: Cryopyrin-Associated Periodic Syndromes (CAPS), including Familial Cold Autoinflammatory Syndrome (FCAS) and Muckle-Wells Syndrome (MWS) in adults and children ages 12 and older.
How To Take It
Rilonacept is taken as an injection. In adults 18 years or older, it is first taken as a loading dose of two subcutaneous injections (injections under the skin), on the same day at two different body sites; each injection has a dose of 160 mg, for a total of 320 mg. It is then followed by weekly subcutaneous injections of a single 160 mg dose.
In children 12–17 years of age, the initial dose is 4.4 mg/kg (up to 320 mg), delivered in either one or two subcutaneous injections. It is then followed by weekly subcutaneous injections of a single 2.2 mg/kg (up to 160 mg) dose.
Side Effects
Rilonacept modulates the body’s ability to fight infections, which may cause you to be more susceptible to viral and bacterial infections. The most common side effects of this drug are injection site reactions, upper respiratory tract infections, nausea, diarrhea, and sinusitis. Injection site reactions include redness, pain, itching or swelling of the area and often resolve with cold compresses, topical steroids or antihistamines. Serious infections and change in lipid profile can happen but are rare.
Tell Your Rheumatology Provider
Tell your healthcare provider if you develop fevers, or any signs or symptoms of an infection. Stop the drug if you develop a serious infection. Tell your healthcare provider if you are pregnant or planning to conceive. You should discuss it with your healthcare provider before receiving any vaccinations. Live vaccines should be avoided while on this medication. You should discuss updating your vaccinations prior to starting this medication.
Reviewed September 2025 by Pankti Reid, MD, MPH, and reviewed by the American College of Rheumatology Communications and Marketing Committee.
This information provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnosis and treatment of a medical or health condition.