Cyclosporine is an immunosuppressive medication used to treat immune-mediated diseases in dogs and cats, such as atopic dermatitis and inflammatory bowel disease. It works by inhibiting the activity of T-cells in the immune system. Cyclosporine is typically given orally and can cause side effects such as vomiting, diarrhea, and decreased appetite. Long-term use can also increase the risk of infections and certain types of cancer.