Hidradenitis suppurativa is a chronic inflammatory disease of the folliculo-infundibular unit for which no individual treatment is uniformly effective. A wide array of therapies has been reported successful in the treatment of hidradenitis, although few high-quality clinical trials have been conducted. Comparing the effectiveness of different therapies has proven challenging due to heterogeneity and limited validation of outcome measures. We performed a systematic review of clinical trials of medical treatments for hidradenitis, yielding 8 articles reporting on 9 trials of antibiotic, hormonal, and biologic therapies. In addition, we discuss existing observational data on commonly used therapeutic regimens, as well as the outcome measures driving clinical research in hidradenitis suppurativa.