Siltuximab: uses, dosing, side effects & brands
Siltuximab is a medicine sold in the U.S. under one brand, for castleman disease. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Treats
- Castleman Disease
- Available as
- Injectable
- Sold as
- Sylvant
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
How siltuximab is dosed
From the FDA label for Sylvant (application BLA125496). Other siltuximab products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
For intravenous infusion only. Administer as an 11 mg/kg dose given over 1 hour by intravenous infusion every 3 weeks. ( 2 ) 2.1 Recommended Dosage Administer SYLVANT 11 mg/kg over 1 hour as an intravenous infusion every 3 weeks until treatment failure. Perform hematology laboratory tests prior to each dose of SYLVANT therapy for the first 12 months and every 3 dosing cycles thereafter. If treatment criteria outlined in Table 1 are not met, consider delaying treatment with SYLVANT. Do not reduce dose. Table 1: Treatment Criteria Laboratory parameter Requirements before first SYLVANT administration Retreatment criteria Absolute Neutrophil Count ≥1.0 × 10 9 /L ≥1.0 × 10 9 /L Platelet count ≥75 × 10 9 /L ≥50 × 10 9 /L Hemoglobin SYLVANT may increase hemoglobin levels in MCD patients <17 g/dL <17 g/dL Do not administer SYLVANT to patients with severe infections until the infection resolves. Discontinue SYLVANT in patients with severe infusion related reactions, anaphylaxis, severe allergic reactions, or cytokine release syndromes. Do not reinstitute treatment. 2.2 Instructions for Preparation and Administration Use aseptic technique for reconstitution and preparation of dosing solution. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit 1. Calculate the dose (mg), total…
Siltuximab side effects
The following clinically significant adverse reactions are also discussed in other sections of the labeling: Concurrent active severe infections [see Warnings and Precautions (5.1) ] Infusion-related reactions and hypersensitivity [see Warnings and Precautions (5.3) ] Gastrointestinal perforation [see Warnings and Precautions (5.4) ] The most common adverse reactions (>10% of patients) were rash, pruritus, upper respiratory tract infection, increased weight, and hyperuricemia. To report SUSPECTED ADVERSE REACTIONS, contact Recordati Rare Diseases Inc., at 1-888-575-8344 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. Study 1, in MCD, was an international, multicenter, randomized Phase 2 study of every 3 week infusions comparing SYLVANT and best supportive care (BSC) to placebo and BSC. There were 53 patients randomized to the SYLVANT arm at a dosage of 11 mg/kg and 26 patients randomized to the placebo arm. Of the 26 placebo-treated patients, 13 patients subsequently crossed-over to receive SYLVANT. The median age was 48 years (range 20 to 78), 66% male, 48% Asian, 39% White,…
Who shouldn’t take siltuximab
Severe hypersensitivity reaction to siltuximab or any of the excipients in SYLVANT [see Warnings and Precautions (5.3) ] . Hypersensitivity reactions, including anaphylactic reaction, hypersensitivity, and drug hypersensitivity have been reported in patients treated with siltuximab. Severe hypersensitivity reaction to siltuximab or any of the excipients in SYLVANT. ( 4 )
Siltuximab drug interactions
7.1 Cytochrome P450 Substrates Cytochrome P450s in the liver are down regulated by infection and inflammation stimuli including cytokines such as IL-6. Inhibition of IL-6 signaling in patients treated with SYLVANT may restore CYP450 activities to higher levels leading to increased metabolism of drugs that are CYP450 substrates compared to metabolism prior to treatment with SYLVANT. Upon initiation or discontinuation of SYLVANT, in patients being treated with CYP450 substrates with a narrow therapeutic index, perform therapeutic monitoring of effect (e.g., warfarin) or drug concentration (e.g., cyclosporine or theophylline) as needed and adjust dose. The effect of SYLVANT on CYP450 enzyme activity can persist for several weeks after stopping therapy. Exercise caution when SYLVANT is co-administered with CYP3A4 substrate drugs where a decrease in effectiveness would be undesirable (e.g., oral contraceptives, lovastatin, atorvastatin).
Every siltuximab product we track (1)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
Only one: Sylvant.
Siltuximab and breastfeeding
From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.
Full LactMed record for siltuximab: levels in milk, effects in breastfed infants, and the drugs it would consider insteadNo information is available on the clinical use of siltuximab during breastfeeding. Because siltuximab is a large protein molecule with a molecular weight of about 145,000 Da, the amount in milk is likely to be very low. It is also likely to be partially destroyed in the infant's gastrointestinal tract and absorption by the infant is probably minimal. Until more data become available, siltuximab should be used with caution during breastfeeding, especially while nursing a newborn or preterm infant. The manufacturer recommends that breastfeeding be discontinued during siltuximab therapy and for 3 months after the last dose.
National Institute of Child Health and Human Development, record revised November 15, 2023. LactMed states its information is not a substitute for professional judgement.
What people report to the FDA about siltuximab
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 318 reports naming siltuximab, and the FDA flagged 89% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- cytokine release syndrome37 reports
- hypertension36 reports
- drug effective for unapproved indication32 reports
- hepatic steatosis31 reports
- cataract30 reports
- cushingoid30 reports
- osteopenia30 reports
- short stature30 reports
Read these as a signal, not a rate. A report does not mean siltuximab caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 26, 2026.
Related calculators
Frequently asked questions
What is siltuximab?
Sylvant (Siltuximab) is a medication used to treat Castleman Disease.
Can you take siltuximab with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run siltuximab against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What forms does siltuximab come in?
Across the brands we track, siltuximab is currently marketed as injectable, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic siltuximab?
We do not currently list a generic-labelled siltuximab product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Siltuximab: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/siltuximab
- MLA
- “Siltuximab: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/siltuximab.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for siltuximab on DailyMed (NIH) ↗.