Ritlecitinib a new oral targeting inhibitor developed by Pfizer in the United States. Ritlecitinib is a medication used for the treatment of severe alopecia areata (hair loss). Ritlecitinib is a kinase inhibitor which inhibits Janus kinase 3 and tyrosine kinase. Clinical studies have proved that ritlecitinib can effectively block signaling molecules and immune cells activity, which are considered to be the cause of alopecia areata. Compared with the first generation of Pan-JAK inhibitors, the side effects  are little than previous drugs because of its precise blockade. Adult and adolescent patients have better survivability on ritlecitinib. The most common side effects were headache, nasopharyngitis, and upper respiratory tract infection. But it can be well relieved after stopping the drug for a period of time. In addition, ritlecitinib is used in non-segmental vitiligo patients aged 12 years or older who are suitable for systemic treatment. This is the third clinical indication of ritlecitinib approved in China after alopecia areata and ulcerative colitis.