On March 20, 2026, the U.S. Food and Drug Administration (FDA) issued a safety warning that requires products containing carbidopa/levodopa to carry new labeling which warns about the potential for Vitamin B6 (pyridoxine) deficiency. The warning guides physicians and other health care professionals to test for baseline vitamin B6 levels (with a blood test) prior to starting patients on treatment with carbidopa/levodopa therapies and periodically while on treatment and to supplement with vitamin B6 as necessary. Of note – it is important that patients do not take vitamin B6 on their own without monitoring blood levels, since vitamin B6 levels that are too high can be dangerous as well.