Sandimmun, also known as cyclosporine, is an immunosuppressive medication primarily used to prevent organ rejection in patients who have undergone kidney, liver, and heart transplants. By inhibiting the activity of the immune system, Sandimmun reduces the risk of the body attacking and rejecting the transplanted organ. Additionally, this medication is used in the treatment of certain autoimmune diseases, such as rheumatoid arthritis and psoriasis, where suppression of the immune system can help manage symptoms. Sandimmun works by specifically targeting and inhibiting the function of T-lymphocytes, a type of white blood cell involved in the immune response. It is available in various forms, including oral capsules and an injectable solution, and its use requires careful monitoring by healthcare professionals to manage potential side effects and ensure the optimal balance between immunosuppression and the risk of infections.