Keytruda (pembrolizumab) is a prescription medication used to treat various types of cancer, including melanoma, lung cancer, and head and neck cancer. Keytruda is a type of immunotherapy drug that works by boosting the immune system to fight cancer cells. Like any medication, Keytruda may cause side effects, but the severity of these side effects can vary depending on the patient.

According to the Keytruda website [2], some of the common side effects of Keytruda include fatigue, cough, nausea, diarrhea, and decreased appetite. Other possible side effects may include skin rash, joint pain, and fever. These side effects are usually mild to moderate in severity and can be managed with medication or other treatments.

However, Keytruda can also cause more severe side effects, known as immune-related adverse events (irAEs). These side effects occur when the immune system attacks healthy cells in the body, leading to inflammation and damage to various organs. Some of the most serious irAEs associated with Keytruda include pneumonitis (inflammation of the lungs), colitis (inflammation of the colon), and hepatitis (inflammation of the liver). These side effects can be life-threatening if not treated promptly [3].

It is important to note that not all patients will experience side effects from Keytruda, and the severity of side effects can vary from person to person. Patients should talk to their doctor about their individual risk of side effects and how to manage them if they occur. Regular check-ups and monitoring are essential for patients taking Keytruda to ensure that any side effects are detected and treated promptly.

Sources:
[1] https://www.drugpatentwatch.com/p/biologics/tradename/KEYTRUDA
[2] https://www.keytruda.com/side-effects/
[3] https://www.cancer.net/navigating-cancer-care/how-cancer-treated/immunotherapy-and-vaccines/side-effects-immunotherapy