Rilonacept Injection
Rilonacept injection (Arcalyst) is an interleukin-1 blocker used to treat rare inflammatory conditions including Cryopyrin-Associated Periodic Syndromes, Deficiency of IL-1 Receptor Antagonist, and recurrent pericarditis.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 1 clinical label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
📖 Rilonacept Injection: Patient Information Guide
A plain-language walkthrough of Rilonacept Injection — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
Rilonacept injection (Arcalyst) is approved for several rare inflammatory conditions driven by overactive IL-1 signaling.
- Arcalyst treats Cryopyrin-Associated Periodic Syndromes (CAPS), including Familial Cold Autoinflammatory Syndrome (FCAS) and Muckle-Wells Syndrome (MWS), in adults and children 12 years and older
- Arcalyst maintains remission of Deficiency of Interleukin-1 Receptor Antagonist (DIRA) in adults and children weighing at least 10 kg (about 22 lbs)
- Arcalyst treats recurrent pericarditis (repeated bouts of inflammation around the heart lining) and reduces the risk of future episodes in adults and children 12 years and older
⚙️How it works▾
Rilonacept is what's called an IL-1 cytokine trap. It acts like a decoy receptor floating in the bloodstream — it grabs onto two inflammatory proteins, interleukin-1 alpha (IL-1α) and interleukin-1 beta (IL-1β), and holds on so tightly that they can't reach the cells they would normally activate. In CAPS, genetic mutations cause an overactive inflammasome (an inflammation-triggering protein complex) that churns out too much IL-1β. In DIRA, the body naturally lacks a protein that keeps IL-1 in check. In recurrent pericarditis, damaged tissue releases IL-1α, which kicks off a self-amplifying cycle of inflammation. By blocking IL-1α and IL-1β, rilonacept interrupts that cycle and calms the inflammation.
💊How it's taken▾
Arcalyst is given as a subcutaneous (under-the-skin) injection, once a week. For CAPS and recurrent pericarditis, treatment typically starts with a higher loading dose on the first day, then continues with a lower weekly maintenance dose; pediatric patients (12–17 years) receive weight-based doses. For DIRA, both adults and children receive a weight-based weekly dose without a separate loading step.
- Inject under the skin — never into a vein
- Rotate injection sites (abdomen, thigh, or upper arm) and avoid bruised, red, tender, or hard skin
- If you miss a dose, inject it within 7 days and then return to your original schedule; if more than 7 days have passed, take the dose and start a new weekly schedule from that date
- Follow your prescriber's exact instructions — do not adjust your dose on your own
🤒Side effects — in detail▾
The most commonly reported side effects with Arcalyst are injection-site reactions and upper respiratory infections.
- Injection-site reactions: redness, swelling, itching, bruising, pain, or warmth at the injection site (most last only 1–2 days)
- Upper respiratory tract infections (colds, congestion)
- Sinusitis (sinus infection)
- Cough
- Nausea
- Increases in cholesterol and triglyceride levels
- Rash (seen in children with DIRA)
- Ear infections and runny nose (seen in children with DIRA)
More serious reactions — including severe infections, allergic reactions, and possible increased cancer risk — require prompt medical attention. Contact your doctor immediately if you develop a high fever, signs of meningitis (severe headache, stiff neck, light sensitivity), or signs of a severe allergic reaction.
⚠️Warnings & precautions▾
- Serious infections: Arcalyst suppresses part of the immune system, raising the risk of serious — even life-threatening — infections. A patient died from bacterial meningitis in a clinical study. Do not start Arcalyst if you have an active or chronic infection, and stop it if a serious infection develops.
- Avoid combining with TNF blockers: Using Arcalyst alongside TNF-blocking drugs (like etanercept or adalimumab) is not recommended — the combination significantly increases infection risk.
- Malignancy (cancer) risk: The long-term impact on cancer risk is not fully known, but immune-suppressing drugs carry a theoretical risk of increasing it.
- Lipid changes: Arcalyst can raise cholesterol and triglyceride levels — your doctor should check your lipid panel during treatment.
- Vaccinations: Live vaccines must be avoided during Arcalyst treatment. Get all recommended vaccines — including pneumococcal and inactivated flu vaccine — before starting therapy, since Arcalyst may reduce vaccine effectiveness.
- Hypersensitivity reactions: Allergic reactions have occurred. If you develop signs of a serious reaction, stop the injection and seek care immediately.
🔀What it interacts with▾
Arcalyst can interact with certain other medications, so tell your prescriber and pharmacist about everything you take.
- TNF-blocking agents (e.g., etanercept, adalimumab, infliximab): combining with Arcalyst greatly raises the risk of serious infections — this combination is not recommended
- Other IL-1 blockers (e.g., anakinra, canakinumab): using alongside Arcalyst is not recommended due to potential additive immune suppression and overlapping pharmacologic effects
- Warfarin and other narrow therapeutic index drugs (medications where even small dose changes matter): Arcalyst may change how these drugs are broken down in the body by normalizing certain liver enzymes — levels should be monitored and doses may need adjustment when starting or stopping Arcalyst
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- Tell your doctor about any active or chronic infection — Arcalyst should not be started until infections are resolved
- Get all recommended vaccines up to date before starting Arcalyst; live vaccines must be avoided during treatment
- Pregnancy: Based on animal studies, rilonacept may cause harm to a developing baby — discuss risks and benefits with your doctor if you are pregnant or planning to become pregnant
- Breastfeeding: It is not known whether rilonacept passes into breast milk — talk to your doctor before breastfeeding
- Children under 12 with CAPS or recurrent pericarditis have not had safety and effectiveness established; children weighing less than 10 kg with DIRA are also excluded
- Pediatric patients on Arcalyst should be monitored for growth and bone development during treatment
- Older adults (65+) may be more vulnerable to serious infections and should be closely monitored
- Kidney or liver impairment: No studies have been done in people with kidney or liver problems — tell your doctor if you have either condition
🚑If you take too much▾
No overdose cases with Arcalyst have been reported. In clinical trials, higher-than-usual doses were given to some patients without clear dose-limiting toxicities, but the maximum safe amount has not been determined. If an overdose is suspected, the guidance is to monitor for any unusual symptoms or side effects and seek appropriate medical care right away.
📡Pharmacodynamics — effects in the body▾
Arcalyst measurably reduces inflammation in the body. In patients with CAPS, it brought average levels of two key inflammation markers — C-Reactive Protein (CRP) and Serum Amyloid A (SAA) — down to normal and kept them there during clinical trials. In DIRA patients, CRP reduction was maintained over a 2-year study. In recurrent pericarditis, rilonacept was associated with resolution of acute episodes, with a median time to CRP normalization of just 7 days.
🔬Pharmacokinetics — how your body processes it▾
Rilonacept is given by subcutaneous injection and reaches steady-state (stable) blood levels in about 6 weeks in CAPS patients and about 2 weeks in recurrent pericarditis patients on a weekly schedule. Its half-life in the body is approximately 7 days, which is why once-weekly dosing works well. No studies have evaluated how kidney or liver disease affects how the body handles rilonacept, so caution is warranted in those populations.
📦How to store it▾
Store refrigerated at 2°C to 8°C (36°F to 46°F) in the original carton to protect from light.
📄 Written from Rilonacept Injection’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
🩺 Pharmacist Counseling Corner
Quick, plain-English answers to the questions patients ask most about Rilonacept Injection — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is Arcalyst treating — is it a steroid or immunotherapy? ▾
How do I give myself the injection, and does it hurt? ▾
What infections should I actually watch out for while on this medication? ▾
Can I get the flu shot or other vaccines while taking Arcalyst? ▾
Does Arcalyst affect any of my other medications? ▾
Is it safe to take Arcalyst if I'm pregnant or trying to get pregnant? ▾
Is Rilonacept Injection available over the counter? ▾
When was Rilonacept Injection first available? ▾
Who makes Rilonacept Injection? ▾
💬 Answers drafted from Rilonacept Injection’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
💊 How Rilonacept Injection comes
Rilonacept Injection is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Injection
How this form is used
- Arcalyst is used to treat Cryopyrin-Associated Periodic Syndromes (CAPS), including Familial Cold Autoinflammatory Syndrome and Muckle-Wells Syndrome, in adults and children 12 and older
- Arcalyst is used to maintain remission of Deficiency of IL-1 Receptor Antagonist (DIRA) in adults and children weighing at least 10 kg
- Arcalyst is used to treat recurrent pericarditis and reduce the risk of it coming back in adults and children 12 and older
- Arcalyst is given as a subcutaneous (under-the-skin) injection only — never intravenously
- Arcalyst must be reconstituted (mixed) with preservative-free Sterile Water for Injection before use; each vial is for single use only
- Arcalyst is typically given once weekly; rotate injection sites among the abdomen, thigh, or upper arm and avoid bruised, red, tender, or hard skin
- After reconstitution, Arcalyst may be kept at room temperature but must be protected from light and used within three hours; discard any unused portion
📊 Rilonacept Injection across the U.S. market
How Rilonacept Injection appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
📈 How widely Rilonacept Injection is used
A general measure of how commonly Rilonacept Injection is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Rilonacept Injection is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Rilonacept Injection prescribed? Of the 1,596 medications we measure, Rilonacept Injection ranks #1,186 by Medicaid prescriptions — more than 26% of them.
Utilization by Rilonacept Injection product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
rilonacept 220 MG Injection
Summed across the 1 of 3 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 763453
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Rilonacept Injection, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 1 of 3 listed Rilonacept Injection NDCs with Medicaid activity.
🔍 Compare Rilonacept Injection products
A representative set of FDA-listed product records for Rilonacept Injection — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Injection | ||||
| 160 mg/2 mL | — | Jubilant HollisterStier LLC × 3 listings | DRUG FOR FURTHER PROCESSING | View NDC → |
| 160 mg/2 mL | Subcutaneous | Kiniksa Pharmaceuticals (UK), Ltd. × 3 listings | BLA | View NDC → |
| 40 mg/mL | — | Regeneron Pharmaceuticals, Inc. | DRUG FOR FURTHER PROCESSING | View NDC → |
Showing 7 of 7 products — FDA National Drug Code Directory. See every product, package size and price: browse all 7 Rilonacept Injection NDCs →
📈 What people report — real-world data (FDA FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Rilonacept Injection — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Rilonacept Injection in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
🏛️ The road to your pharmacy
How Rilonacept Injection went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 Recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
Source: openFDA drug enforcement (recall) reports.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 763450 1 dose form · 1 strength
-
Dose form (SCDF) Injection RxCUI 1724259In current FDA listingsClinical drug / strength (SCD) 220 MGRxCUI 763453
Look up RxCUI 763450 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
📦 Supply & shortage status
Whether Rilonacept Injection is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
🏷️ Sold under these brand names
🏭 Manufacturers & labelers
RxNorm drug class
Rilonacept Injection belongs to the Interleukin inhibitors class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
🔬 Where this comes from
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 1 FDA-filed SPL label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Kiniksa Pharmaceuticals (UK), Ltd. is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.