5-alpha reductase inhibitors are a class of medications that block the action of an enzyme responsible for the conversion of testosterone to dihydrotestosterone (DHT). DHT is a more potent form of testosterone and is responsible for many of the masculine characteristics associated with puberty and adulthood. Blocking the production of DHT can help to feminize hormone therapy. There are two types of 5-alpha reductase inhibitors: oral and topical. Oral 5-alpha reductase inhibitors, such as finasteride (Proscar) and dutasteride (#Avodart), are taken in pill form and can be effective in reducing DHT levels by up to 70%. Topical 5-alpha reductase inhibitors, such as alfinestride (#Propecia) and epristeride (#Androcur), are applied directly to the scalp or skin where they can be absorbed into the blood stream. They are less effective than oral medications, but they have fewer side effects. Both oral and topical 5-alpha reductase inhibitors can cause sexual dysfunction, including decreased libido, problems with erection, ejaculatory difficulties, and infertility. They may also cause breast enlargement or tenderness, headaches, rash or skin irritation where applied topically,. However,, these side effects tend to be milder than those caused by other #feminizing #hormones therapies such as #estrogens #health #medicines