Would Taking Dutasteride and Finasteride Cancel Each Other Out?

Dear Doctor,
after 6 years of Propecia, I have started to take also 1mg of Dutasteride daily. Would the daily combination of finastride and dutasteride run the risk of making both drugs ineffective?

I would not suggest that you take both medications at the same time — as both are prescription medications, you should be discussing that with your doctor. That being said… no, they won’t cancel each other out. These medications work roughly the same way on the mechanism for hair loss. There is a suggestion that dutasteride is a bit more powerful than finasteride, but there are more side effects and the dose in dutasteride to get a better DHT block is high (2.5 mg/day). There are reports that these higher doses may cause infertility in some men and we do not know if this is reversible. At this time, dutasteride is not FDA approved for the treatment of hair loss. For more on dutasteride, see past posts here.