The National Institutes of Health (US NIH, 2018) estimates that in the US 
approximately 50 million men and 30 million women suffer from AGA (also known as 
pattern hair loss). Minoxidil is the only topical drug for the treatment of both 
female and male pattern hair loss. In the US, minoxidil is approved 
over-the-counter (OTC) at a maximum concentration of 5%. In this review, we 
summarize the findings of the pivotal studies used in support of the drug's 
approval as well as recent discoveries and novel developments in the use of 
minoxidil for the treatment of AGA.