Q: I heard that Propecia stops working after five years. Is this true and why in five years? — B.P., Stamford, CT

A: That is not correct. Although the effects of Propecia (finasteride 1mg) will diminish over time, it does continue to work. Using finasteride long-term will still be better than stopping it at some arbitrary interval. In clinical practice, I often increase the dose of finasteride, after someone had been on the medication 3 to 5 years, to help maintain its effectiveness.