One placebo-controlled trial found a benefit of dutasteride for PMDD, but no trials have examined finasteride yet. Additional trials of these medications will be necessary before they are approved for widespread use. One concern with the use of dutasteride is that it can cause birth defects for months after it is discontinued, making careful birth control an important consideration for any female taking this medication. There is some expert consensus that birth defects are less likely with finasteride, since it leaves the system faster than dutasteride; however, finasteride has not been tested against placebo for PMDD. Some physicians do use these medications “off-label” for the treatment of PMDD, and carefully monitor their patients to determine whether it seems to be beneficial and safe. Overall, while 5-alpha reductase blockers such as dutasteride and finasteride may be a promising new approach to treatment, additional trials are needed to understand their effectiveness and safety before they can be recommended for widespread use.”

-Tory Eisenlohr-Moul, PhD July 1, 2019