Cyclosporin-A is an effective immunosuppressive agent that is chiefly responsible for improved success rates with kidney, heart, and liver transplants. It also has been found to be effective in some autoimmune diseases. It was studied in a number of clinical trials in MS, the largest involving 547 patients with chronic progressive disease. It was found to slightly reduce the progression rate and delay the time to requiring use of a wheelchair. These marginal to modest benefits from treatment, however, are outweighed by the long-term toxicity of the drug in impairing kidney function and causing hypertension.

In the opinion of the Committee, cyclosporin-A has some efficacy, but the association with serious side-effects makes it an unsuitable therapy in MS.