From the Guidelines
Keytruda (pembrolizumab) can cause various side effects ranging from mild to severe, including common side effects such as fatigue, diarrhea, nausea, pruritus, rash, and musculoskeletal pain, as well as more serious immune-related adverse reactions like pneumonitis, colitis, hepatitis, and nephritis, as reported in the most recent study 1.
Common Side Effects
- Fatigue
- Diarrhea
- Nausea
- Pruritus
- Rash
- Musculoskeletal pain
- Anorexia
- Constipation
- Fever
- Cough
- Dyspnea
Serious Side Effects
- Pneumonitis (lung inflammation)
- Colitis (intestinal inflammation)
- Hepatitis (liver inflammation)
- Nephritis (kidney inflammation)
- Endocrinopathies (hormone gland problems)
- Severe skin reactions
- Infusion reactions
According to the study published in the Journal of the National Comprehensive Cancer Network 1, the most common adverse events from pembrolizumab were fatigue, pruritus, diarrhea, anorexia, constipation, nausea, rash, fever, cough, dyspnea, and musculoskeletal pain. Additionally, pembrolizumab may be associated with immune-mediated side effects, which include colitis, hepatitis, endocrinopathies, pneumonitis, or nephritis. Another study published in 2021 2 also reported similar common adverse effects with pembrolizumab, including fatigue, pruritus, diarrhea, anorexia, constipation, nausea, rash, fever, cough, dyspnea, and musculoskeletal pain. However, the most recent and highest quality study 1 is prioritized for its findings on the side effects of Keytruda.
It is essential for patients to immediately report any new or worsening symptoms to their healthcare provider, especially breathing problems, diarrhea, yellowing of skin, severe abdominal pain, headaches, or changes in urine output, as these could be indicative of more serious side effects. Regular monitoring through blood tests and physical exams is also crucial during treatment with Keytruda, as reported in the study 1. The side effects of Keytruda occur because it works by enhancing the immune system's ability to detect and fight cancer cells, but this can sometimes lead to the immune system attacking healthy tissues as well.
From the FDA Drug Label
What are the possible side effects of KEYTRUDA? KEYTRUDA can cause serious side effects. See “What is the most important information I should know about KEYTRUDA? ” Common side effects of KEYTRUDA when used alone include: feeling tired, pain, including pain in muscles, rash, diarrhea, fever, cough, decreased appetite, itching, shortness of breath, constipation, bones or joints and stomach-area (abdominal) pain, nausea, and low levels of thyroid hormone Side effects of KEYTRUDA when used alone that are more common in children than in adults include: fever, vomiting, headache, stomach area (abdominal) pain, and low levels of white blood cells Common side effects of KEYTRUDA when given with certain chemotherapy or chemotherapy with radiation therapy medicines include: feeling tired or weak, nausea, constipation, diarrhea, decreased appetite, rash, vomiting, cough, trouble breathing, fever, hair loss, inflammation of the nerves that may cause pain, weakness, and paralysis in the arms and legs, swelling of the lining of the mouth, nose, eyes, throat, intestines, or vagina, mouth sores, headache, weight loss, stomach-area (abdominal) pain, joint and muscle pain, trouble sleeping, bleeding, blisters, or rash on the palms of your hands and soles of your feet, urinary tract infection, and low levels of thyroid hormone Common side effects of KEYTRUDA when given with chemotherapy and bevacizumab include: tingling or numbness of the arms or legs, hair loss, low red blood cell count, feeling tired or weak, nausea, low white blood cell count, diarrhea, high blood pressure, decreased platelet count, constipation, joint aches, vomiting, urinary tract infection, rash, low levels of thyroid hormone, and decreased appetite Common side effects of KEYTRUDA when given with axitinib include: diarrhea, feeling tired or weak, high blood pressure, liver problems, low levels of thyroid hormone, decreased appetite, blisters or rash on the palms of your hands and soles of your feet, nausea, mouth sores or swelling of the lining of the mouth, nose, eyes, throat, intestines, or vagina, hoarseness, rash, cough, and constipation Common side effects of KEYTRUDA when given with lenvatinib include: low levels of thyroid hormone, high blood pressure, feeling tired, diarrhea, joint and muscle pain, nausea, decreased appetite, vomiting, mouth sores, weight loss, stomach-area (abdominal) pain, urinary tract infection, protein in your urine, constipation, headache, bleeding, blisters or rash on the palms of your hands and soles of your feet, hoarseness, rash, liver problems, and kidney problems. Common side effects of KEYTRUDA when given with enfortumab vedotin include: rash, tingling or numbness of the arms or legs, feeling tired, itching, diarrhea, hair loss, weight loss, decreased appetite, dry eye, nausea, constipation, changes in sense of taste, and urinary tract infection
The common side effects of Keytruda include:
- Feeling tired or weak
- Pain, including pain in muscles
- Rash
- Diarrhea
- Fever
- Cough
- Decreased appetite
- Itching
- Shortness of breath
- Constipation
- Nausea
- Low levels of thyroid hormone
- Hair loss
- Inflammation of the nerves
- Swelling of the lining of the mouth, nose, eyes, throat, intestines, or vagina
- Mouth sores
- Headache
- Weight loss
- Stomach-area (abdominal) pain
- Joint and muscle pain
- Trouble sleeping
- Bleeding
- Blisters or rash on the palms of your hands and soles of your feet
- Urinary tract infection
- High blood pressure
- Liver problems
- Kidney problems
- Dry eye
- Changes in sense of taste 3
From the Research
Keytruda Side Effects
- Immune-related adverse events (irAEs) are a common side effect of Keytruda (pembrolizumab) treatment, including rare immune-mediated inflammation due to autoimmune mechanisms 4
- Gastrointestinal side effects: + Colitis: mucosal inflammation of the rectum and sigmoid colon, resembling ulcerative colitis 4 + Pancreatitis: resembling type 2 autoimmune pancreatitis, with infiltration of inflammatory cells, mainly neutrophils 4
- Endocrinopathies: + Type 1 diabetes mellitus 5 + Autoimmune thyroiditis 5
- Respiratory side effects: + Pneumonitis: a rare but known complication of pembrolizumab treatment, with a median time frame of appearance of 2.8 months, but can occur as early as 48 hours after treatment initiation 6, 7 + Organising pneumonia: with patchy ground-glass opacities and basal perilobular consolidation 7
- Treatment of side effects: + Steroid therapy: effective in improving symptoms of colitis, pancreatitis, and pneumonitis 4, 6, 7