A gender reassignment program for male to female transsexuals normally includes reducing androgen effects with spironolactone (cyproterone has been used in European countries) and stimulating feminization of secondary sex characteristics with estrogen.
There can be risks attached to hormone therapy in both men and women and therefore it is definitely inadvisable to take any form of hormone product unless it is medically prescribed.
The use of progesterone to augment breast development is controversial in physicians treating MTF transsexuals. When deciding on a hormone regimen, prescribers should remember that it is estrogen that causes the serious side effects, so the lowest effective dose should be used.
The manufacturers of oestrogen and progesterone products specify them for medical use in females and do not acknowledge their use for transsexuals, so there is little clinical data available regarding this usage.
Apart from a summary provided below, two excellent sites for information on hormones and dosages are: