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Pembrolizumab Side Effects

In Summary

More frequently reported side effects include: hyperthyroidism. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to pembrolizumab: intravenous powder for solution, intravenous solution

Along with its needed effects, pembrolizumab 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 pembrolizumab:

More common
  • Bloating or swelling of the face, arms, hands, lower legs, or feet
  • body aches or pain
  • chills
  • constipation
  • cough
  • depressed mood
  • difficulty with breathing
  • difficulty with moving
  • dry skin and hair
  • ear congestion
  • feeling cold
  • fever
  • hair loss
  • headache
  • hoarseness or husky voice
  • loss of voice
  • muscle cramps, pain, and stiffness
  • pain in the joints
  • pale skin
  • rapid weight gain
  • runny or stuffy nose
  • slowed heartbeat
  • sneezing
  • sore throat
  • tingling of the hands or feet
  • trouble breathing
  • troubled breathing with exertion
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • unusual weight gain or loss
Less common
  • Chest pain
  • general feeling of discomfort or illness
  • nervousness
  • pain
  • sensitivity to heat
  • stomach cramps
  • sweating
  • tenderness
  • thickening of bronchial secretions
  • trouble sleeping
  • watery or bloody diarrhea
  • weight loss
  • Back, leg, or stomach pains
  • bleeding gums
  • blurred vision or other change in vision
  • cracks in the skin
  • darkened urine
  • drowsiness
  • eye pain
  • fast heartbeat
  • general body swelling
  • general tiredness and weakness
  • indigestion
  • light-colored stools
  • loss of appetite
  • loss of heat from the body
  • nausea
  • nosebleeds
  • pain, swelling, or redness in the joints
  • pains in the stomach, side, or abdomen, possibly radiating to the back
  • pale skin
  • red, swollen skin
  • redness of the eye
  • scaly skin
  • seizures
  • sensitivity of the eye to light
  • tearing
  • upper right abdominal or stomach pain
  • vomiting
  • yellow eyes and skin

Some side effects of pembrolizumab 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

For Healthcare Professionals

Applies to pembrolizumab: intravenous powder for injection, intravenous solution


Very common (10% or more): Peripheral edema (up to 17%)[Ref]


Very common (10% or more): Pruritus (up to 30%), rash (up to 29%), vitiligo (up to 11%)
Uncommon (0.1% to 1%): Exfoliative dermatitis[Ref]


Very common (10% or more): Hyperglycemia (up to 40%), hypertriglyceridemia (up to 25%)
Common (1% to 10%): Hypothyroidism, hyperthyroidism
Uncommon (0.1% to 1%): Hypophysitis, adrenal insufficiency[Ref]


Very common (10% or more): Nausea (up to 30%), constipation (up to 21%), diarrhea (up to 20%), vomiting (up to 16%), abdominal pain (up to 12%)
Common (1% to 10%): Colitis
Uncommon (0.1% to 1%): Pancreatitis[Ref]


Very common (10% or more): Anemia (up to 55%), immune-mediated hemolytic anemia[Ref]


Very common (10% or more): Hypoalbuminemia (up to 34%), increased aspartate aminotransferase (up to 24%)
Uncommon (0.1% to 1%): Hepatitis[Ref]


Very common (10% or more): Hyponatremia (up to 35%), decreased appetite (up to 26%), hypocalcemia (up to 24%)[Ref]


Very common (10% or more): Arthralgia (up to 20%), pain in extremity (up to 18%), myalgia (up to 14%), back pain (up to 12%)
Uncommon (0.1% to 1%): Arthritis, myositis, myasthenic syndrome, rhabdomyolysis[Ref]

Nervous system

Very common (10% or more): Headache (up to 16%), dizziness (up to 11%)
Uncommon (0.1% to 1%): Partial seizures[Ref]


Uncommon (0.1% to 1%): Uveitis, optic neuritis[Ref]


Very common (10% or more): Fatigue (up to 47%), chills (up to 14%), pyrexia (up to 11%), sepsis (up to 10%)[Ref]


Very common (10% or more): Insomnia (up to 14%)[Ref]


Uncommon (0.1% to 1%): Nephritis, renal failure[Ref]


Very common (10% or more): Cough (up to 30%), dyspnea (up to 18%), upper respiratory tract infection (up to 11%)
Common (1% to 10%): Pneumonitis[Ref]


1. "Product Information. Keytruda (pembrolizumab)." Merck & Company Inc, Whitehouse Station, NJ.

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online. Available from: URL:" ([2006]):

Some side effects of pembrolizumab may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

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