Abstract: In recent years, small molecule drugs and targeted biological agents have been increasingly applied in the treatment of hair loss diseases by specifically interfering with immune pathways. Based on current clinical research, this article systematically evaluated the clinical efficacy and safety profiles of various small molecule drugs and targeted biological agents in the treatment of moderate-to-severe AA. By integrating the latest clinical trials and real-world data, it deeply analyzed the similarities and differences in treatment response, recurrence, and long-term tolerance between the two types of drugs, further clarified their potential as new therapies, and promoted the development of future precision treatment.

Key words: alopecia areata, JAK inhibitors, biologics, small molecule drugs