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Overview: Sylvant is used for multicentric Castleman disease (MCD), a condition where you have many enlarged lymph nodes. This medicine works by blocking a substance that causes swelling. The most common side effects are rash, itchiness, common cold symptoms, and weight gain. While less common, serious side effects may include reactions during your infusion, allergic reactions, or stomach problems. Tell your health care provider right away if you think you have an infection during Sylvant treatment.

Uses

What is Sylvant used for?

Sylvant (siltuximab) is commonly used for multicentric Castleman disease (MCD). It is a rare condition where your lymph nodes become abnormally enlarged in several areas of your body. Sylvant is used to treat this condition in people who are not infected with HIV or human herpesvirus-8 (HHV-8).

Sylvant may also be used for other conditions as determined by your health care provider.

How does Sylvant work (mechanism of action)?

Multicentric Castleman disease (MCD) may cause enlarged lymph nodes due to high levels of interleukin-6 (IL-6). Sylvant works by blocking IL-6, a substance made by the body that causes swelling (inflammation). This can help reduce swollen lymph nodes and related symptoms in some people with MCD.

How is Sylvant supplied (dosage forms)?

Brands and other names

  • Sylvant

Dosage forms and strengths

Sylvant is available in an injectable form that is given by a health care provider.

How should I store Sylvant?

Sylvant is usually given by a health care provider in a hospital or clinic. You will not store it at home.

Side Effects

What are the most common side effects of Sylvant?

The most common side effects of Sylvant are listed below. Tell your health care provider if you have any of these side effects that bother you.

There may be other side effects of Sylvant that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of Sylvant?

While less common, the most serious side effects of Sylvant are described below, along with what to do if they happen.

Severe Allergic Reactions. Sylvant may cause allergic reactions, which can be serious. Get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Infusion Reactions. A dose of Sylvant is given as an infusion into a vein at a hospital or clinic. It usually takes about an hour. Some people have had serious reactions during the infusion. Your infusion may need to be slowed or stopped if you have these reactions. Tell your health care provider right away if you have any of the following symptoms of a serious infusion-related reaction.

  • Trouble breathing
  • Dizziness
  • Back pain
  • Chest pain
  • Nausea and vomiting
  • Flushing or redness
  • Feeling of skipped heartbeats

Stomach Tears. Sylvant may cause tears (perforation) in your gut. Get emergency help if you have any of the following symptoms.

  • Stomach pain
  • Upset stomach
  • Vomit or poop that looks bloody or black

Warnings & Precautions

Who should not use Sylvant?

Allergies to Ingredients. People who are allergic to any of the following should not use Sylvant.

  • Siltuximab
  • Sylvant
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in Sylvant.

What should I know about Sylvant before using it?

Sylvant is usually given by a health care provider in a hospital or clinic.

Sylvant can affect your immune system. Tell your health care provider right away if you have an infection or think you have symptoms of an infection while using Sylvant. Do not get a vaccine during your treatment with Sylvant unless your health care provider recommends it.

What should I tell my health care provider before using Sylvant?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if Sylvant is right for you.

In particular, make sure that you discuss any of the following.

Severe Infection. Sylvant can hide the symptoms of an infection and change how your body responds to an infection. Tell your health care provider if you may have an infection. They may wait to start your Sylvant treatment until after your infection has been treated or goes away. 

Vaccines. Talk with your health care provider about any vaccines that you may need. You should not receive certain vaccines right before or while using Sylvant. Tell your health care provider about any vaccines you have recently received or have scheduled.

Other Medicines and Supplements. Sylvant may interact with other medicines and supplements. Before using Sylvant, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Other Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Stomach or bowel problems, such as ulcers or diverticulitis
  • Severe kidney or liver problems
  • Infection

Pregnancy. It is not known if or how Sylvant could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant. To avoid getting pregnant, use birth control during treatment with Sylvant and for three months after your last dose. 

If you become pregnant while using Sylvant, the medicine may affect your baby’s immune system. Your baby is more likely to get infections and certain vaccines may be risky. You and your health care provider can discuss these risks and decide if your baby will get certain vaccines. 

Breastfeeding. It is not known if Sylvant passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should stop breastfeeding or stop Sylvant. Do not breastfeed during treatment with Sylvant and for three months after your last dose. 

How can I get more information about Sylvant?

For more information about Sylvant, you can visit the drugmaker’s website at www.sylvant.com or call them at 888-575-8344.

Interactions

Does Sylvant interact with foods or drinks?

There are no known interactions between Sylvant and foods or drinks.

It is unknown if drinking alcohol will affect Sylvant, but heavy drinking can slow your immune response and make it harder for your body to fight infections.

Does Sylvant interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before using Sylvant.

  • A birth control pill
  • Warfarin, which is a blood thinner
  • Cyclosporine (Gengraf, Neoral, Sandimmune, and others), which is a medicine that suppresses your immune system
  • Theophylline (Elixophyllin, Theo-24), which is a medicine for asthma or certain other breathing problems
  • A statin, such as atorvastatin (Lipitor and others) or lovastatin, which is a medicine to lower cholesterol

Sylvant may alter the blood levels of many other medicines. Tell your health care provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with Sylvant. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much Sylvant?

If you or someone else has used too much Sylvant, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of Sylvant?

Sylvant is usually given by a health care provider in a hospital or clinic. If you miss an appointment to get your Sylvant dose, call to reschedule as soon as possible.