Topical minoxidil has been used for almost 40 years to treat alopecia. There is growing evidence supporting off-label use of low-dose oral minoxidil.To conduct a systematic review evaluating the use of oral minoxidil for all types of alopecia.A primary literature search was conducted using PubMed in May 2019, utilizing the search term "oral minoxidil AND (hair loss OR alopecia OR baldness)". Reviews, non-English studies, and articles concerning only topical minoxidil were excluded.Ten articles were included for review comprising a total 19,218 patients (215 women and 19,003 men). Oral minoxidil dose ranged from 0.25 to 5 mg daily to twice daily. The strongest evidence existed for androgenetic alopecia and alopecia areata (AA), with 61-100% and 18-82.4% of patients demonstrating objective clinical improvement. Successful treatment of female pattern hair loss, chronic telogen effluvium, monilethrix, and permanent chemotherapy-induced alopecia was also reported. The most common adverse effects with oral minoxidil included hypertrichosis and postural hypotension.Oral minoxidil is a safe and successful treatment of androgenic alopecia and AA. In addition to its therapeutic benefits, practical advantages over topical minoxidil stem from improved patient compliance.