Yervoy (ipilimumab) is a medication used to treat advanced melanoma, a type of skin cancer. According to the sources provided, Yervoy may cause several side effects, some of which can be severe.

The most common side effects of Yervoy include fatigue, diarrhea, itching, rash, nausea, vomiting, loss of appetite, and headache. These side effects are usually mild to moderate and go away on their own. However, some patients may experience more severe side effects, such as inflammation of the intestines, liver, and lungs, as well as hormonal imbalances that can affect the thyroid, pituitary, and adrenal glands.

The Mayo Clinic [2] reports that Yervoy can also cause serious immune system reactions, including inflammation of the colon, liver, and lungs, as well as nerve damage that can lead to muscle weakness and paralysis. In rare cases, Yervoy can cause severe allergic reactions that can be life-threatening.

It is important to note that Yervoy can also affect the immune system's ability to fight infections, which can increase the risk of infections and make them more severe. Patients taking Yervoy should be monitored closely for signs of infection and should avoid contact with people who have contagious illnesses.

In conclusion, Yervoy can cause several side effects, some of which can be severe. Patients taking Yervoy should be aware of the potential side effects and should report any unusual symptoms to their healthcare provider immediately. It is important to weigh the potential benefits of Yervoy against the risks of side effects before starting treatment.

Sources:
[1] https://www.drugpatentwatch.com/p/biologics/tradename/YERVOY
[2] https://www.mayoclinic.org/drugs-supplements/ipilimumab-intravenous-route/side-effects/drg-20074841
[3] https://www.yervoy.com/side-Effects