Arcalyst Side Effects Center

Last updated on RxList: 8/15/2022
Arcalyst Side Effects Center

What Is Arcalyst?

Arcalyst (rilonacept) is an interleukin inhibitor used to treat some of the symptoms of rare genetic conditions such as Familial Cold Auto-inflammatory Syndrome (FCAS) or Muckle-Wells Syndrome (MWS).

What Are Side Effects of Arcalyst?

Common side effects of Arcalyst include:

  • cold symptoms (sneezing, runny or stuffy nose, sore throat, cough)
  • nausea
  • stomach pain
  • diarrhea
  • numbness or tingly feeling
  • injection site reactions (pain, swelling, redness, itching, bleeding, warmth, blistering, or other irritation)

Tell your doctor if you have serious side effects of Arcalyst including:

  • bloody, black, or tarry stools,
  • coughing up blood or vomit that looks like coffee grounds,
  • wheezing,
  • chest tightness,
  • trouble breathing,
  • pain or burning when you urinate,
  • headache,
  • neck stiffness,
  • increased sensitivity to light,
  • purple spots on the skin, and/or
  • seizure (convulsions).

Arcalyst may cause serious side effects including:

  • hives,
  • difficulty breathing,
  • swelling of your face, lips, tongue, or throat,
  • dizziness,
  • fever,
  • chills,
  • sore throat,
  • open sores on your body,
  • cough with mucus,
  • shortness of breath,
  • headache,
  • neck stiffness,
  • increased sensitivity to light,
  • confusion,
  • chest discomfort,
  • wheezing,
  • dry cough,
  • rapid weight loss,
  • bloody, black, or tarry stools,
  • coughing up blood,
  • vomit that looks like coffee grounds,
  • pain or burning when you urinate,
  • ear pain or full feeling,
  • trouble hearing,
  • drainage from the ear, and
  • fussiness in a child

Get medical help right away, if you have any of the symptoms listed above.

Seek medical care or call 911 at once if you have the following serious side effects:

  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in your chest; shortness of breath; and sudden dizziness, lightheartedness, or passing out;
  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors.

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

Dosage for Arcalyst

For adults, treatment with Arcalyst should be initiated with a loading dose of 320 mg delivered as two, 2 mL, subcutaneous injections of 160 mg each given on the same day at two different sites. Dosing should be continued with a once-weekly injection of 160 mg administered as a single, 2-mL, subcutaneous injection.

What Drugs, Substances, or Supplements Interact with Arcalyst?

Arcalyst may interact with etanercept, adalimumab, infliximab, blood thinners, cyclosporine, digoxin, theophylline, seizure medications, or heart rhythm medications. Tell your doctor all medications and supplements you use.

Arcalyst During Pregnancy and Breastfeeding

During pregnancy, Arcalyst should be used only if prescribed. It may be harmful to a fetus. Tell your doctor if you are pregnant or plan to become pregnant during treatment. It is unknown if this drug passes into breast milk or if it could harm a nursing baby. Consult your doctor before breastfeeding.

Additional Information

Our Arcalyst (rilonacept) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Arcalyst Consumer Information

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

You may get infections more easily, even serious or fatal infections. Call your doctor right away if you have signs of infection such as:

  • fever, chills, sore throat;
  • open sores on your body;
  • cough with mucus, feeling short of breath;
  • headache, neck stiffness, increased sensitivity to light, confusion; or
  • chest discomfort, wheezing, dry cough, rapid weight loss.

Also call your doctor at once if you have:

  • bloody, black, or tarry stools;
  • coughing up blood or vomit that looks like coffee grounds;
  • wheezing, chest tightness, trouble breathing;
  • pain or burning when you urinate; or
  • signs of an ear infection--fever, ear pain or full feeling, trouble hearing, drainage from the ear, fussiness in a child.

Common side effects may include:

  • cold symptoms such as stuffy nose, runny nose, sneezing, sore throat;
  • ear infection;
  • muscle or joint pain;
  • rash; or
  • pain, swelling, redness, itching, warmth, blistering, bleeding, bruising, a rash, or a lump where the medicine was injected.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Arcalyst Professional Information


The following clinically significant adverse reactions are described elsewhere in the labeling.

  • Serious Infections [see WARNINGS AND PRECAUTIONS]
  • Risk of Malignancy[see WARNINGS AND PRECAUTIONS]
  • Hypersensitivity Reactions [see WARNINGS AND PRECAUTIONS]
  • Lipid Profile Changes [see WARNINGS AND PRECAUTIONS]

Clinical Trial Experience

Clinical trials are conducted under widely varying conditions and, as such, adverse reaction rates observed cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

The data described herein reflect exposure to ARCALYST in over 2,000 patients who received at least one dose, including approximately 1700 exposed to 160 mg or more, of whom 151 patients were exposed for at least 6 months and 111 patients for at least one year. These included patients with CAPS and RP, patients with other diseases, and healthy volunteers.


Approximately 60 patients with CAPS were treated weekly with 160 mg of ARCALYST. The pivotal trial population included 47 patients with CAPS. These patients were between the ages of 22 and 78 years (average 51 years). Thirty-one patients were female and 16 were male. All of the patients were White/Caucasian. Six pediatric patients (12 to17 years) were enrolled directly into the open-label extension phase of the trial.

Part A of the clinical trial was conducted in patients with CAPS who were naive to treatment with ARCALYST. Part A of the study was a randomized, double-blind, placebo-controlled, six-week study comparing ARCALYST to placebo [see Clinical Studies]. Table 1 reflects the frequency of adverse events reported by at least two patients during Part A.

Table 1: Most Frequent Adverse Reactions in Patients with CAPS (Part A, Reported by at Least Two Patients)

Adverse Event ARCALYST 160 mg
(n = 23)
(n= 24)
Any AE 17 (74%) 13 (54%)
Injection-site reactions 11 (48%) 3 (13%)
Upper respiratory tract infection 6 (26%) 1 (4%)
Nausea 1 (4%) 3 (13%)
Diarrhea 1 (4%) 3 (13%)
Sinusitis 2 (9%) 1 (4%)
Abdominal pain upper 0 2 (8%)
Cough 2 (9%) 0
Hypoesthesia 2 (9%) 0
Stomach discomfort 1 (4%) 1 (4%)
Urinary tract infection 1 (4%) 1 (4%)


In a 2-year, open-label study, 6 pediatric patients with DIRA, 3 years to 6 years of age, received 2.2 to 4.4 mg/kg dose of ARCALYST once weekly [see Clinical Studies]. The safety profile was generally consistent with that seen in patients with CAPS. The most common adverse reactions were upper respiratory infection (6 of 6), rash (5 of 6), otitis media (3 of 6), pharyngitis (3 of 6) and rhinorrhea (3 of 6).


In the RP phase 3 study, a total of 86 patients received at least one dose of ARCALYST with a median treatment duration of 9 months [see Clinical Studies]. Of the patients, 49 (57%) were female and 37 (43%) were male; 93% were White/Caucasians. The mean age was 44.7 years. Seven patients (8%) were aged 12-17 years old. No new adverse reactions were identified in this study.

Adverse Reactions Of Special Interest

Injection-Site Reactions

In patients with CAPS or RP, the most common and consistently reported adverse event associated with ARCALYST was injection-site reaction (ISR). The ISRs included erythema, swelling, pruritus, mass, bruising, inflammation, pain, edema, dermatitis, discomfort, urticaria, vesicles, warmth and hemorrhage. Most injection-site reactions lasted for one to two days.


During Part A in the CAPS study, the incidence of patients reporting infections was greater with ARCALYST (48%) than with placebo (17%). In Part B, randomized withdrawal, the incidence of infections was similar in the ARCALYST (18%) and the placebo patients (22%). Part A of the trial was initiated in the winter months, while Part B was predominantly performed in the summer months.

In placebo-controlled studies across a variety of patient populations encompassing 360 patients treated with rilonacept and 179 treated with placebo, the incidence of infections was 34% and 27% (2.15 per patient-exposure year and 1.81 per patient-exposure year), respectively, for rilonacept and placebo.

Serious Infections

Six serious infections were reported by four patients during the CAPS clinical program: Mycobacterium intracellulare infection; gastrointestinal bleeding and colitis; sinusitis and bronchitis; and Streptococcus pneumoniae meningitis [see ADVERSE REACTIONS].

One patient receiving ARCALYST for an unapproved indication in another study 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. One 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.

Changes In Hematologic Parameters Laboratory Changes

One patient in a study in an unapproved indication developed transient neutropenia (ANC < 1 x 109/L) after receiving a large dose (2000 mg intravenously) of ARCALYST. The patient did not experience any infection associated with the neutropenia.

Lipid Profile Changes

Patients with CAPS treated with ARCALYST 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.


As with all therapeutic proteins, there is potential for immunogenicity. The detection of antibody formation is highly dependent on the sensitivity and specificity of the assay. The data reflect the percentage of patients whose test results were positive for antibodies to the rilonacept receptor domains in specific assays. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay is highly dependent on several factors including assay sensitivity and specificity, assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to rilonacept with the incidence of antibodies in other studies or to other products may be misleading.

Antibodies directed against the receptor domains of rilonacept were detected by an ELISA assay in patients with CAPS after treatment with ARCALYST. Nineteen of 55 patients (35%) who had received ARCALYST for at least 6 weeks tested positive for treatment-emergent binding antibodies on at least one occasion. Of the 19, seven tested positive at the last assessment (Week 18 or 24 of the open-label extension period), and five patients tested positive for neutralizing antibodies on at least one occasion. There was no correlation of antibody activity and either clinical effectiveness or safety.

In the Phase 3 study of patients with RP there were no patients who tested positive for antibodies at baseline. At any point in time, 26 out of 86 (30%) subjects tested positive at any assessment and of these, 6 tested positive for neutralizing antibodies (NAb). At the last assessment, 10 subjects remained positive for anti-drug antibodies (ADA) and 1 subject remained positive for NAb. There was no correlation of antibody activity and either clinical effectiveness or safety.


TNF-Blocking Agent And IL-1 Blocking Agent

Specific drug interaction studies have not been conducted with ARCALYST. Concomitant administration of another drug that blocks IL-1 with a TNF-blocking agent in another patient population has been associated with an increased risk of serious infections and an increased risk of neutropenia. The concomitant administration of ARCALYST with TNF-blocking agents may also result in similar toxicities and is not recommended [see WARNINGS AND PRECAUTIONS]. The concomitant administration of ARCALYST with other drugs that block IL-1 has not been studied. Based upon the potential for pharmacologic interactions between rilonacept and a recombinant IL-1ra, concomitant administration of ARCALYST and other agents that block IL-1 or its receptors is not recommended.

Cytochrome P450 Substrates

The formation of CYP450 enzymes is suppressed by increased levels of cytokines (e.g., IL-1) during chronic inflammation. Thus it is expected that for a molecule that binds to IL-1, such as rilonacept, the formation of CYP450 enzymes could be normalized. This is clinically relevant for CYP450 substrates with a narrow therapeutic index, where the dose is individually adjusted (e.g., warfarin). Upon initiation of ARCALYST, in patients being treated with these types of medicinal products, therapeutic monitoring of the effect or drug concentration should be performed, and the individual dose of the medicinal product may need to be adjusted as needed.

Read the entire FDA prescribing information for Arcalyst (Rilonacept)

© Arcalyst Patient Information is supplied by Cerner Multum, Inc. and Arcalyst Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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