Use dropper to apply directly onto scalp on the top and/or crown of head each morning and evening. Apply to towel dry or dry hair (does not need to be freshly shampooed). Allow one to two minutes to dry before applying other treatments or styling products (may apply other treatments, leave-in conditioners or styling product after applying Regrowth Treatment), style as usual.
"This is an oral, prescription-only medication with the brand name Propecia that’s also FDA approved to treat hair loss," says Spencer. Male pattern hair loss occurs when a hormone called dihydrotestosterone (DHT) prevents hair follicles from getting the nutrients they need. Finasteride works by blocking the production of DHT, which protects the follicles.
Propecia's 1 mg dose of finasteride can effectively lower DHT levels in the scalp by as much as 60% when taken daily. It is DHT that shrinks or miniaturizes the hair follicle, which eventually leads to baldness. This 60% reduction in DHT has proven to stop the progression of hair loss in 86% of men taking the drug during clinical trials. 65% of trial participants had what was considered a substantial increase of hair growth.
In either sex, hair loss from androgenetic alopecia occurs because of a genetically determined shortening of anagen, a hair's growing phase, and a lengthening of the time between the shedding of a hair and the start of a new anagen phase. (See "Life cycle of a hair.") That means it takes longer for hair to start growing back after it is shed in the course of the normal growth cycle. The hair follicle itself also changes, shrinking and producing a shorter, thinner hair shaft — a process called "follicular miniaturization." As a result, thicker, pigmented, longer-lived "terminal" hairs are replaced by shorter, thinner, non-pigmented hairs called "vellus."