Minoxidil solution has been clinically studied and is proven to be effective against hair loss (alopecia areata). Studies have shown that noticeable results can be seen after just 3 moths of treatment when used twice a day (with one 1 ml application in the morning and one 1 ml application in the evening). Generally, Minoxidil 2% is recommended for women and a 5% minoxidil solution is recommended for men.