Cyproterone is a steroidal antiandrogen that was researched in the 1960s and 1970s but was never introduced for medical use. It is an analog of cyproterone acetate (CPA), an antiandrogen, progestin, and antigonadotropin that was introduced in place of cyproterone and is widely used as a medication. Cyproterone and CPA were among the first antiandrogens to be developed. It is important to clarify that the term cyproterone is often used as a synonym and abbreviation for cyproterone acetate, and when the term occurs, confusingly, it almost always means CPA and not really cyproterone. Cyproterone itself, unlike CPA, has never been introduced for medical use and is therefore not available as a drug. Therefore, only cyproterone acetate, which is in use, will be discussed below. CPA is used as a progestin and antiandrogen in hormonal birth control and in the treatment of androgen-dependent conditions. Specifically, CPA is used in combined birth control pills, in the treatment of androgen-dependent skin and hair conditions such as acne, seborrhea, excessive hair growth and scalp hair loss, high androgen levels, in transgender hormone therapy, to treat prostate cancer, to reduce sex drive in sex offenders or men with paraphilias or hypersexuality, to treat early puberty, and for other purposes. It is used in both low doses and higher doses.