Trade name for medroxyprogesterone acetate. Provera is a tabletized form of the same drug that is found in Depo-Provera. Often Provera is used as a trial run for Depo-Provera as an adverse reaction to Provera will indicate a possible intolerance of progestins. It is much easier to discontinue treatment with Provera than with Depo-Provera, as Depo-Provera is a monthly or three-monthly deep depot injection; once you're stuck with it, you're stuck with it.
Provera is used to treat irregular menstruation, endometriosis, osteoporosis, puberty-related autoimmune syndromes, menopause symptoms and other illnesses that come free with an X chromosome. It is used (somewhat erroneously) as a cruelty-free version of Premarin and is equally effective in treating some (especially menopausal) conditions. It's normally used in tandem with an estrogen.
Provera has in the past been used to subdue aggressive sex offenders and in some misguided attempts to 'cure' homosexuality. Notably, Alan Turing was dosed with the stuff. Progestins generally have an anti-androgenic effect as they can compete with testosterone for the same receptor site; they are however not especially efficient and drugs like Androcur, flutamide, GnRH analogs and finasteride are recommended instead.
Provera has a number of side effects, including blood thickening and clotting disorders. Liver-related problems tend to be exacerbated over its cousin Depo-Provera as the oral administration route takes it through the liver twice, once on the way into the body and once on the way out. Progestins of all kinds can cause psychological effects and extensive 'tuning' of regime may need to take place to find the patient's comfort zone. Provera is especially suspected to cause depression. As progesterone is a female hormone it does tend to cause sore breasts in women, headache in everyone and gynecomastia in men. It also tends to make women horny.
Patients taking Provera, especially phenotypically male patients, should be checked for liver function regularly. Underweight patients should be watched especially as they are more sensitive to overload with steroid hormones, as they have less adipose tissue for peripheral aromatization.