Keytruda is a brand name for the drug pembrolizumab, which is a type of immunotherapy used to treat certain types of cancer. Immunotherapy drugs like Keytruda work by boosting the body's immune system to fight cancer cells. While Keytruda has been shown to be effective in treating cancer, it can also cause some side effects.

According to the Keytruda website [2], the most common side effects of Keytruda include fatigue, cough, nausea, itching, rash, decreased appetite, constipation, joint pain, and diarrhea. These side effects are usually mild to moderate in severity and can be managed with medication or other supportive measures.

More serious side effects can also occur, although they are less common. These can include severe allergic reactions, inflammation of the lungs, liver problems, kidney problems, and endocrine disorders. Patients who experience any of these symptoms should seek medical attention immediately.

Immunotherapy drugs like Keytruda can also cause autoimmune reactions, where the immune system attacks healthy cells in the body. This can lead to a variety of symptoms depending on which part of the body is affected. For example, autoimmune reactions can cause skin rashes, joint pain, or thyroid problems [3].

It's important to note that not everyone who takes Keytruda will experience side effects, and the severity of side effects can vary from person to person. Patients should talk to their doctor about any concerns they have about side effects and work with their healthcare team to manage any symptoms that do occur.

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