Belatacept is used to help prevent organ rejection in people who have received a kidney transplant. It is used along with other medications (such as mycophenolate, corticosteroids) to allow your new organ to function normally. Belatacept belongs to a class of drugs known as immunosuppressants.  Belatacept prevents organ rejection after a kidney transplant. Limit the amount of time you spend in sunlight. Avoid using tanning beds or sunlamps. Wear protective clothing and use sunscreen. Belatacept belongs to group of drugs called selective T-cell costimulation blockers. Common side effects of belatacept include low red blood cell count (anemia), diarrhea, and kidney or bladder infection.