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Siltuximab Side Effects

Medically reviewed by Last updated on Mar 6, 2023.

Applies to siltuximab: intravenous powder for solution.

Serious side effects of Siltuximab

Along with its needed effects, siltuximab may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking siltuximab:

More common

  • Black, tarry stools
  • bleeding gums
  • bloating or swelling of the face, arms, hands, lower legs, or feet
  • bloody urine
  • blurred vision
  • body aches or pain
  • chills
  • confusion
  • cough
  • decreased frequency or amount of urine
  • difficulty with breathing
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • ear congestion
  • fever
  • full or bloated feeling
  • headache
  • increased thirst
  • loss of appetite
  • loss of voice
  • lower back or side pain
  • nasal congestion
  • nausea
  • pinpoint red spots on the skin
  • pressure in the stomach
  • rapid weight gain
  • runny nose
  • sneezing
  • sore throat
  • stomach pain
  • sweating
  • swelling of the abdominal or stomach area
  • tingling of the hands or feet
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • unusual weight gain or loss
  • vomiting

Less common

  • Back pain
  • chest pain or discomfort
  • dizziness
  • dry mouth
  • fainting
  • fast, irregular, pounding, or racing heartbeat or pulse
  • feeling of warmth
  • flushing or redness of the skin
  • lightheadedness
  • rapid breathing
  • redness of the face, neck, arms, and occasionally, upper chest
  • sunken eyes
  • unusually warm skin
  • wrinkled skin


  • Difficulty with swallowing
  • hives, itching, or skin rash
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • tightness in the chest

Other side effects of Siltuximab

Some side effects of siltuximab may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Difficulty having a bowel movement
  • difficulty with moving
  • joint pain, stiffness, or swelling
  • muscle pain or stiffness
  • rash with flat lesions or small raised lesions on the skin

Less common

  • Darkening of the skin
  • decreased appetite
  • dry skin
  • skin rash, encrusted, scaly, and oozing

For Healthcare Professionals

Applies to siltuximab: intravenous powder for injection.


The most common adverse reactions were pruritus, weight gain, rash, hyperuricemia, and upper respiratory tract infection.[Ref]


Very common (10% or more): Upper respiratory tract infection (63%), nasopharyngitis (13%)

Common (1% to 10%): Lower respiratory tract infection, oropharyngeal pain[Ref]


Very common (10% or more): Rash (28%), pruritus (28%), eczema

Common (1% to 10%): Skin hyperpigmentation, psoriasis, dry skin[Ref]


Very common (10% or more): Diarrhea (32%), abdominal pain/abdominal distention (12%), oropharyngeal pain, nausea, vomiting, constipation, gastroesophageal reflux disease, mouth ulceration

Frequency not reported: Gastrointestinal perforation[Ref]


Very common (10% or more): Weight gain (19%), hyperuricemia (11%), localized edema

Common (1% to 10%): Hypertriglyceridemia, hypercholesterolemia, decreased appetite, dehydration[Ref]


Very common (10% or more): Edema (26%), hypertension

Common (1% to 10%): Hypotension[Ref]


Common (1% to 10%): Anaphylactic reaction[Ref]


Very common (10% or more): Fatigue (21%)[Ref]


Very common (10% or more): Pain in extremities (21%), arthralgia (21%)[Ref]


Common (1% to 10%): Renal impairment[Ref]


Very common (10% or more): Thrombocytopenia, neutropenia[Ref]

Nervous system

Very common (10% or more): Headache, dizziness[Ref]


Uncommon (0.1% to 1%): Positive test for anti-siltuximab antibodies[Ref]


Common (1% to 10%): Infusion related reactions (e.g., back pain, chest pain/discomfort, nausea, vomiting, flushing, erythema, palpitations)[Ref]


Very common (10% or more): Urinary tract infection[Ref]


1. Product Information. Sylvant (siltuximab). Janssen Biotech, Inc. 2014.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.