Dutastride inhibits both type I and type II forms of 5-alpha reductase up to 90%. As such Dutastride inhibits DHT.
DHT is the potent male hormone dihydrotestosterone.
By lowering DHT you increase the androgen to estrogen balance in favor of estrogens.
The mechanism is very similar to that of Proscar and Propecia.
Known side effects are feminization (more female like appearance, with gynecomastia and feminine fat storage patterns and loss of libido and even erections.
For a minority of men this has become a permanent problem even after the treatment has been withdrawn.
In other words it has led to a permanent hormone problem that sometimes has to be treated often for life.
Below is a website of a man who has suffered permanent damage from reduction of DHT. There is a link to a yahoo group dedicated to men who are suffering from similar problems across the world.
www.propeciasideeffects.com Do not touch this medication with a barge pole if you enjoy being a man!
Just to illustrate the fact that I am not blowing this out of proportion;
At this time Dutastride is only approved and available for treatment of prostate enlargement.
Reducing DHT is a form of chemical castration.