Skip to Content

Arcalyst Side Effects

Generic Name: rilonacept

Note: This document contains side effect information about rilonacept. Some of the dosage forms listed on this page may not apply to the brand name Arcalyst.

In Summary

Common side effects of Arcalyst include: upper respiratory tract infection and injection site reaction. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to rilonacept: subcutaneous powder for solution

Along with its needed effects, rilonacept (the active ingredient contained in Arcalyst) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking rilonacept:

More Common

  • Bleeding, blistering, burning, coldness, discoloration of skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at site
  • body aches or pain
  • chills
  • cough
  • difficulty in breathing
  • ear congestion
  • fever
  • headache
  • loss of voice
  • nasal congestion
  • runny nose
  • sneezing
  • sore throat
  • unusual tiredness or weakness

Incidence Not Known

  • Bloody or black, tarry stools
  • constipation
  • cough producing mucus
  • lower back or side pain
  • pain or tenderness around eyes and cheekbones
  • painful or difficult urination
  • severe stomach pain
  • shortness of breath or troubled breathing
  • tenderness
  • tightness of chest or wheezing
  • vomiting of blood or material that looks like coffee grounds

Some side effects of rilonacept may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More Common

  • Burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings

Less Common

  • Stomach discomfort

For Healthcare Professionals

Applies to rilonacept: subcutaneous powder for injection


In patients with Cryopyrin-Associated Periodic Syndromes (CAPS), the most common and consistently reported adverse event associated with rilonacept (the active ingredient contained in Arcalyst) was injection-site reaction (ISR). The ISRs included erythema, swelling, pruritis, mass, bruising, inflammation, pain, edema, dermatitis, discomfort, urticaria, vesicles, warmth, and hemorrhage. Most injection-site reactions lasted for one to two days. No ISRs were assessed as severe, and no patient discontinued study participation due to an ISR.[Ref]

Local side effects including injection-site reactions (48%) have been reported.[Ref]


One subject receiving rilonacept (the active ingredient contained in Arcalyst) for an unapproved indication developed an infection in his olecranon bursa with Mycobacterium intracellulare. The patient was on chronic glucocorticoid treatment. The infection occurred after an intraarticular glucocorticoid injection into the bursa with subsequent local exposure to a suspected source of mycobacteria. The patient recovered after the administration of the appropriate antimicrobial therapy.

A patient treated for another unapproved indication developed bronchitis/sinusitis, which resulted in hospitalization.

One patient died in an open-label study of CAPS from Streptococcus pneumoniae meningitis.[Ref]

Immunologic side effects including infections (34%) have been reported.[Ref]


Respiratory side effects including upper respiratory tract infection (26%), sinusitis (9%), and cough (9%) have been reported.[Ref]

Nervous system

Nervous system side effects including hypoesthesia (9%) have been reported.[Ref]


Gastrointestinal side effects including nausea (4%) diarrhea (4%) and stomach discomfort (4%) have been reported.[Ref]


Hematologic side effects have been reported including one case of transient neutropenia (ANC less than 1 x 109/L) after receiving a large dose (2000 mg intravenously) of rilonacept (the active ingredient contained in Arcalyst) Patients with CAPS treated with rilonacept experienced increases in their mean total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides. The mean increases from baseline for total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides were 19 mg/dL, 2 mg/dL, 10 mg/dL, and 57 mg/dL respectively after 6 weeks of open-label therapy.[Ref]

The patient did not experience any infection associated with the neutropenia.

Physicians should monitor the lipid profiles of their patients (for example after 2 to 3 months) and consider lipid-lowering therapies as needed based upon cardiovascular risk factors and current guidelines.[Ref]


Genitourinary side effects including urinary tract infection (4%) have been reported.[Ref]


1. "Product Information. Arcalyst (rilonacept)." Regeneron Pharmaceuticals Inc, Tarrytown, NY.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.