From the Guidelines
Keytruda (pembrolizumab) commonly causes side effects related to its mechanism as an immune checkpoint inhibitor, with the most frequent side effects including fatigue, musculoskeletal pain, decreased appetite, itching, diarrhea, nausea, rash, fever, cough, shortness of breath, and constipation, as reported in the most recent study 1.
Common Side Effects
The most common adverse events from pembrolizumab are:
- Fatigue
- Pruritus
- Diarrhea
- Anorexia
- Constipation
- Nausea
- Rash
- Fever
- Cough
- Dyspnea
- Musculoskeletal pain These side effects are well-documented in the literature, with the most recent study 1 providing a comprehensive overview of the common adverse events associated with pembrolizumab.
Immune-Mediated Side Effects
More serious immune-related adverse reactions can occur as Keytruda works by activating the immune system, which may lead to inflammation in various organs, including:
- Pneumonitis (lung inflammation)
- Colitis (intestinal inflammation)
- Hepatitis (liver inflammation)
- Endocrinopathies (hormone gland problems like thyroid disorders, diabetes, or adrenal insufficiency)
- Nephritis (kidney inflammation)
- Skin reactions These immune-mediated side effects are a concern with pembrolizumab treatment, and patients should be closely monitored for any signs of inflammation or immune-related adverse reactions, as reported in 1.
Management of Side Effects
Patients should immediately report symptoms like severe diarrhea, shortness of breath, yellowing of skin, severe abdominal pain, persistent headaches, or unusual fatigue to their healthcare provider. These side effects can develop at any time during treatment or even after treatment has ended, so ongoing monitoring is essential. Most side effects can be managed effectively if caught early, sometimes requiring corticosteroids or hormone replacement therapy, as noted in 1.
From the FDA Drug Label
The most common adverse reactions (incidence ≥20%) of pemetrexed for injection, when administered in combination with pembrolizumab and platinum chemotherapy, are fatigue/asthenia, nausea, constipation, diarrhea, decreased appetite, rash, vomiting, cough, dyspnea, and pyrexia Table 2: Adverse Reactions Occurring in ≥20% of Patients in KEYNOTE-189 Pemetrexed for injection Pembrolizumab Platinum Chemotherapy n=405 Adverse ReactionAll Gradesa (%)Grade 3-4 (%) Gastrointestinal Disorders Nausea563.5 Constipation351.0 Diarrhea3152 Vomiting243.7 General Disorders and Administration Site Conditions Fatigueb56125 Pyrexia200.2 Metabolism and Nutrition Disorders Decreased appetite281.5 Skin and Subcutaneous Tissue Disorders Rashc252.0 Respiratory, Thoracic and Mediastinal Disorders Cough2102 Dyspnea213.7
The common side effects of Keytruda (pembrolizumab) are:
- Fatigue/asthenia
- Nausea
- Constipation
- Diarrhea
- Decreased appetite
- Rash
- Vomiting
- Cough
- Dyspnea
- Pyrexia 2
From the Research
Common Side Effects of Keytruda (Pembrolizumab)
- Immune-related adverse events, such as hypophysitis, thyroiditis, and adrenal insufficiency, have been reported in patients treated with pembrolizumab 3, 4, 5, 6
- Endocrinopathies, including thyroid dysfunction, insulin-deficient diabetes mellitus, primary adrenal insufficiency, and hypophysitis, are potential side effects of pembrolizumab 5
- Hematological adverse events, such as thrombotic thrombocytopenic purpura, have also been reported in patients treated with pembrolizumab 7
- Other potential side effects include rash, colitis, hepatitis, and pneumonitis 7
Rare but Serious Side Effects
- Hypophysitis, a rare side effect, can be life-threatening if not promptly diagnosed and treated 3, 5, 6
- Adrenal insufficiency, another rare side effect, can occur during or after treatment with pembrolizumab 4
- Thrombotic thrombocytopenic purpura, a rare and life-threatening side effect, has been reported in patients treated with pembrolizumab 7