Frequently Asked Questions


Frequently Asked Questions icon


SYLVANT® is a prescription medicine that is used to treat patients with Multicentric Castleman’s Disease (MCD) who do not have human immunodeficiency virus (HIV) and human herpesvirus-8 (HHV-8) infection. It was not studied in patients with MCD who are HIV positive or HHV-8 positive because SYLVANT® did not bind to virally produced interleukin-6 (IL-6) in a nonclinical study. It is not known if SYLVANT® is safe and effective in children.

A doctor or nurse in a hospital or clinic will give you SYLVANT® as an intravenous (IV) infusion. It is given slowly over a period of 1 hour.

The recommended dosing of SYLVANT® is once every 3 weeks.

Even if you are not experiencing symptoms and are feeling better, it is important to continue to receive treatment with SYLVANT® for as long as your doctor recommends.

You may have symptom relief, and your doctor will order tests to assess how you are doing on treatment. But it is also important for you to tell your doctor how you are feeling during each visit. To learn more about Multicentric Castleman’s Disease (MCD) and SYLVANT®, or to access a tool to help you track symptoms, click here

Though the cause of MCD is not fully understood, it is believed that a protein in the body called interleukin-6 (IL-6) has a role in the disease.

When produced in the normal amounts, IL-6 helps regulate the activity of the immune system. Often, high levels of IL-6 are seen in patients with MCD. As a result, white blood cells called lymphocytes multiply too rapidly. This causes the lymph nodes to become enlarged, and other symptoms may occur.

SYLVANT® may cause serious side effects, including:


SYLVANT® may lower your ability to fight infections. Tell your healthcare provider right away if you have any signs or symptoms of an infection during treatment with SYLVANT®.

Infusion and allergic reactions

If you have an infusion or allergic reaction while receiving SYLVANT®, your healthcare provider will stop your infusion and treat your reaction. If you have a severe infusion or allergic reaction, your healthcare provider may stop your treatment completely. Tell your healthcare provider or get medical help right away if you have any of these symptoms during or after your infusion of SYLVANT®: trouble breathing, chest tightness, wheezing, dizziness or light-headedness, swelling of the lips, or skin rash.

The most common SYLVANT® side effects include:

  • Rash
  • Itching
  • Upper respiratory tract infection
  • Weight gain
  • Increased blood level of uric acid

Tell your healthcare provider if you have any side effect that bothers you or that does not go away.

These are not all the possible side effects of SYLVANT®.

Report any signs of new or worsening medical conditions to your healthcare provider.

Call your doctor for medical advice about side effects.

Learn more in Important Safety Information

SYLVANT® works by blocking the action of an important protein called interleukin-6 (IL-6), a substance produced in the lymph nodes. SYLVANT® is a monoclonal antibody that prevents IL-6 from binding to IL-6 receptors.

Patients should not receive SYLVANT® if they have had a severe allergic reaction to siltuximab or any of the ingredients in SYLVANT®. The active ingredient in SYLVANT® is siltuximab. The inactive ingredients are L-histidine and L-histidine monohydrochloride monohydrate, polysorbate 80, and sucrose.

Even if you are not experiencing symptoms and are feeling better, it is important to continue to receive treatment with SYLVANT® for as long as your doctor recommends.

Before you receive SYLVANT®, tell your healthcare provider about all of your medical conditions, including if you:

  • have an infection. You should not receive SYLVANT® if you have a severe infection.
  • have had a recent vaccination or are scheduled to receive any vaccinations. You should not receive a live vaccine during your treatment with SYLVANT®.
  • have or have had any stomach or bowel (intestine) problems, such as diverticulitis or ulcers. Tell your healthcare provider if you have pain in your stomach area.
  • are pregnant or plan to become pregnant. It is not known if SYLVANT® will harm your unborn baby. You should not become pregnant while receiving treatment with SYLVANT®. Females who are able to become pregnant should use effective birth control during treatment with SYLVANT® and for 3 months after stopping treatment.
  • are breastfeeding or plan to breastfeed. It is not known if SYLVANT® passes into your breast milk. You and your healthcare provider should decide if you will take SYLVANT® or breastfeed. You should not do both.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements

General information about the safe and effective use of SYLVANT®

Medicines are sometimes prescribed for purposes other than those listed in a Patient Information leaflet. You can ask your healthcare provider or pharmacist for information about SYLVANT® that is written for health professionals.

Report any signs of new or worsening medical conditions to your healthcare provider.

You are encouraged to report negative side effects of prescription drugs to the FDA.

Visit, or call 1-800-FDA-1088 (1-800-332-1088).

Janssen CarePath can assist you in identifying options to help reduce medication out-of-pocket costs, whether you have commercial insurance, government-funded insurance (such as Medicare), or are uninsured. A range of options are below.

If you have commercial insurance

You may be eligible for the Janssen CarePath Patient Rebate Program to save on your co-pay, co-insurance, and deductible costs for SYLVANT®. If eligible and enrolled, you pay $50 per infusion and receive a rebate up to $1,000 per infusion for your medication costs. The costs of intravenous-infusion services are not covered by this program. The program exhausts 12 months from your first eligible date of service, and you may be able to re-enroll to continue receiving a benefit. For additional information about the Janssen CarePath Patient Rebate Program, call 1-855-299-8844, Monday-Friday, 8:00 AM-8:00 PM ET.

Enroll in one easy step

Download, complete, and sign the , obtain physician’s signature, and submit enrollment form to the program.
Fax: 1-855-578-1689 or
Mail: Patient Rebate Program, 14001 Weston Parkway, Suite 103, Cary, NC 27513

5 Simple Steps to receive rebate if enrolled
  1. You receive infusion treatment with SYLVANT®.
  2. Your physician’s office/hospital/infusion provider submits a claim to your insurance company.
  3. You and your physician’s office/hospital/infusion provider receive an Explanation of Benefits (EOB) statement from your insurance company. You or your physician’s office mails or faxes the EOB to the Janssen CarePath Patient Rebate Program.
  4. A Janssen CarePath Patient Rebate Program Coordinator reviews the EOB, determines your rebate amount, and mails you a rebate check within 5-7 business days.

For full eligibility requirements and restrictions, click here.

If you have government-funded insurance, such as Medicare

Janssen CarePath can refer you to the Medicare Savings Plan program, so that you can learn more about eligibility and program benefits and how a Medicare Savings Plan can help you pay for Medicare Part B products. To learn more, click here.

If you are uninsured

Johnson & Johnson Patient Assistance Foundation, Inc., is committed to providing access to uninsured patients who lack the financial resources to pay for their medicines. If you need SYLVANT® and are uninsured and unable to pay for medicine, you should call the program at 800-652-6227, or visit the foundation website at to see if you might qualify for assistance.

Learn more about the Johnson & Johnson Patient Assistance Foundation.

For a comprehensive list of additional programs to help with your medication costs, visit