Odd as it may sound, a number of chemotherapy drugs are used to treat rheumatoid arthritis, usually in lower doses than when used to treat cancer. Rheumatoid arthritis is an
autoimmune condition in which an abnormal immune reaction causes the inflammation of the joints. When used to treat cancer, chemotherapy drugs are given to kill off tumor cells, but in cases of rheumatoid arthritis the drugs are given to slow cell reproduction and decrease the metabolic processes that lead to the inflammation.
The chemotherapy drugs most often used to treat rheumatoid arthritis include methotrexate, Imuran, and cytoxan. Some of the same side effects can occur as occur during cancer treatment, but they are usually not as severe because the drugs are prescribed at lower doses. For more information about the side effects of chemotherapy, see our list of helpful resources.