Some people also find it helpful to add an anti-androgen.
Progesterone consistently administered with estrogen seems to reduce the risk of fibrosis, cysts, and cancer from administration of estrogen alone. Moreover, progestins have a slightly androgenic effect in some people, and apparently can even antagonize estrogen absorption. Spironolactone and finasteride are recommended. Post-ops rarely find any antiandrogen useful except for finasteride. Of transsexuals taking estrogen, those who are older than 25 or so seem to find the anti-androgen much more important than those who are younger.