Alopecia areata, as an example, is an autoimmune disease that causes patchy or complete hair loss, including on the head, body, eyebrows and eyelashes. But more than 50 percent of 66 patients treated with the drug Xeljanz (tofacitinib citrate) saw hair regrowth in three months. The patients took 5 milligrams of Xeljanz twice a day for three months. The drug is normally used as treatment for moderate to severe rheumatoid arthritis. Xeljanz appears to work by stopping the immune system’s attack on hair follicles. 11 million Americans have alopecia areata. However, Dr. Brett King, an assistant professor of dermatology at the Yale School of Medicine, in New Haven is doubtful that Xeljanz will work for the most common types of hair loss (such as male pattern baldness), which are not the result of an autoimmune disease. Treatment with Xeljanz is costing as much as $40,000 a year and for the instant it may not be covered by insurance for that use.