This information was forwarded to me by a dermatologist friend of mine via email.

The UC Berkeley Wellness Letter expressed concern about the unproven long-term safety of Propecia and recommended cutting a standard 1 milligram dose into quarters to reduce the cost without reducing its effectiveness.

This claim appears to be supported by clinical pharmacological data reviewed by the FDA during Propecia's approval process that suggested that the advantage of taking 1 mg per day over 0.2 mg per day is statisticially small. Some people have unsuccessfully petitioned the FDA to re-examine the approved dosage in light of the statistical evidence and unknown long-term risks. The FDA responded and said that just because the level of DHT found in the scalp was not signifigantly different does not mean there is a correlation with Hair loss. A study would have to show that the benefits of using 0.2 mg and 1 mg were not statistically different. According to the FDA such a study has been performed and a 1 mg dose has a greater benefit.

Supporters of Propecia respond that while the drug must be taken for a lifetime in order to avoid losing hair, future treatments are widely expected by baldness specialists to replace Propecia, which would end the need for continued use.