Dutasteride is not FDA-cleared for use on hair loss. It also has a very long half-life of 5-6 weeks in the bloodstream and many, many months in your body. That means if you develop side effects and stop the medications, the side effects can last up to a year. Finasteride, on the other hand, has a bloodstream half-life of 4-6 hours, and if you stop it, it will be out of your system in weeks, not months. The FDA also cleared finasteride for hair loss use.