Cyproterone acetate (CPA) is a progestin (synthetic progesterone, which is a hormone present in both males and females) that typically is used to treat prostate cancer. While it has not been approved by the U.S. FDA (Food and Drug Administration) to treat acne, doctors sometimes prescribe it to treat acne in women. This is called off-label prescribing, and it is a common practice with many medications.1
As a 2014 article in Clinics in Dermatology states, “Androgens play an important role in [skin oil] production and excretion. This subsequently contributes to the formation of acne lesions.”2 Because anti-androgens reduce the amount of androgens circulating in the body, they can help clear up acne lesions.1
Because anti-androgens reduce the amount of male hormones, doctors prescribe CPA for women only when treating acne. Cyproterone acetate can be taken either alone, but when used for acne, it is almost always prescribed in the form of a birth control pill (combined oral contraceptive - COC) that contains both CPA and an estrogen. In fact, researchers recommend that CPA by itself be prescribed only for women who no longer have a uterus or ovaries or who cannot tolerate estrogens.3
When taken alone, the recommended dose of CPA is 50–100mg. This is significantly higher than the dose present in COCs, which is 2mg. When taken alone, it should be started on either the first or fifth day of the menstrual cycle and stopped on the fourteenth day, just before ovulation. In contrast, COCs containing CPA should be taken daily.1
Is Cyproterone Acetate Effective in Treating Acne?
Several studies indicate that CPA is effective in treating acne, typically producing a 37-90% reduction in acne. All of these studies look at CPA given with estrogen in a COC. There are no studies on CPA taken alone for acne.
A 2004 review in The European Journal of Contraception and Reproductive Health Care summarized the results of clinical trials that investigated the effectiveness of CPA in reducing acne. Here are the trials that were included in the review:
- A 1986 randomized, double-blind trial compared three different COCs. Double-blind means that neither the women nor the researchers knew which treatment the women received. Two of the COCs contained CPA: one had 35 micrograms of estrogen and 2mg of CPA, and the other had 50 micrograms of estrogen and 2mg of CPA. After six months of treatment, all of the women taking a CPA-containing COC experienced a 70–72% reduction in acne lesions. The difference in results between the two CPA-containing COCs was not significant, meaning that they worked about the same. The women taking the non-CPA COC experienced a 35% reduction in acne lesions. The review article did not mention whether the difference between the CPA-containing COCs and the other COC was significant.
- A 1988 double-blind trial compared a COC containing 35 micrograms of estrogen and 2mg of CPA with a COC containing 50 micrograms of estrogen and 2mg of CPA. After nine months, between 57% and 63% of the women experienced significant improvement in their acne. The difference between the results of the different COCs was not significant either.
- A 1990 randomized trial compared two different COCs, one of which contained CPA. After nine months, 81–86% of the women taking the CPA-containing COC experienced a significant improvement in their acne. In women taking the non-CPA COC, 63–80% experienced significant improvement. The review did not mention whether the different between the CPA-containing COC and the non-CPA one was significant.
- A 1990 trial compared a COC containing 35 micrograms of estrogen and 2mg of CPA with a COC containing 50 micrograms of estrogen and 2mg of CPA. After 12 months, acne improved by 71% to 72%. The difference in results between the two COCs was negligible.
- A 1990 trial evaluated a COC containing 35 micrograms of estrogen and 2mg of CPA in 890 women. After six months, 83% of the women experienced more than a 50% reduction in the number of acne lesions.
- A 1990 trial evaluated a COC containing 35 micrograms of estrogen and 2mg of CPA (brand name, Diane-35) in 1161 women. After 36 months, 100% of the women experienced significantly improved acne of the face and chest, and 89% of the women experienced significant improvement of acne on the back.
A 2002 randomized, double-blind trial compared a COC containing 35 micrograms of estrogen with another COC. In the 82 women taking the CPA-containing COC, the average acne lesion count decreased by 62.5% after nine months of treatment. The average lesion count in women taking the non-CPA COC decreased by 58.8%. The review did not mention whether the difference between the two COCs was significant.4
More recently, a 2009 randomized, double-blind trial published in Contraception compared the effectiveness of a COC that contained CPA, one that did not, and a placebo in women with mild to moderate acne. After six months of treatment with the CPA-containing COC, the average number of inflammatory acne lesions decreased by 64.6%, and the average number of total lesions decreased by 53.6%. Overall, 90.2% of the women taking the CPA-containing COC experienced improvement of their facial acne. This study found also that the CPA-containing COC worked about the same as the non-CPA COC and that both worked better than the placebo.5 Because this study also included data from multiple countries, the evidence is strong.
Overall improvement with CPA-containing COCs was between 37% and 90%. In addition, these studies suggest that improvement occurs slowly, over a period of several months. It is important to note, however, that all COCs are effective in reducing acne, whether they contain CPA or a different progestin. Because of this and that CPA was evaluated in the context of only a COC, we cannot determine from this data how much of the improvement in acne was due to CPA and how much was due to the estrogen in the COCs.
Side Effects of Cyproterone Acetate
Cyproterone acetate can cause several side effects, including:
- Menstrual irregularities, such as bleeding more or less than normal and breakthrough bleeding (bleeding between menstrual periods)
- Breast tenderness
All of these side effects tend to lessen or disappear over time. In addition, menstrual irregularities are less frequent when CPA is combined with an estrogen in the COC. A less common but more serious side effect of CPA is liver toxicity, which is dose dependent, meaning that it is more likely to occur with high doses.1
Venous Thromboembolism (VTE)
One serious concern when taking any COC, especially one that contains CPA, is the risk of venous thromboembolism (VTE), which is a clot in a blood vessel. Venous thromboembolism can result in serious health problems and even in death. Risk factors that increase the risk of VTE include older age, obesity, smoking, immobilization, such as long periods of bed rest or being in a cast, and some blood clotting diseases. The risk of VTE generally is low in young, healthy women, unless they are affected by any of these risk factors.2
Two studies report an increased risk of VTE when taking a COC that contains CPA, however, as we will see, other studies did not replicate these findings.
A 2001 study in The Lancet compared the risk of VTE in women taking a COC that contained CPA with the risk in women taking one that contained another progestin called levonorgestrel. The researchers concluded that the risk of VTE was four times higher in women taking a COC containing CPA.6
A 2003 study in Human Reproduction investigated the risk of VTE in women taking a COC that contained CPA. This study performed two different analyses. In the first, women taking the CPA-containing COC were at more than twice the risk of VTE compared to women taking a different COC. In the second analysis, women taking the CPA-containing COC had almost three times the risk of VTE compared to women taking a different COC. However, the authors noted that they could not exclude other factors that could have influenced their results.7
Other studies found that the risk of VTE is not higher in CPA-containing COCs when compared to most other COCs.
A 2004 study in Pharmacoepidemiology and Drug Safety used the same research-design as the 2003 study in Human Reproduction. The authors found that women taking a CPA-containing COC had twice the risk of VTE compared to women taking a different COC. However, this difference was not statistically significant, and they concluded that the risk of VTE is not higher for those taking CPA-containing COCs than for those taking a different one.8
A 2014 systematic review (a rigorous literature review that combines the results of many studies into a single analysis) in the Cochrane Database of Systematic Reviews evaluated the risk of VTE when taking a COC. This review included 26 studies and concluded that the risk of VTE is more than three times higher in people taking any COC than in those not taking one. However, CPA-containing COCs carried about the same risk as COCs containing other progestins, such as gestodene, desogestrel, and drospirenone. In addition, this review found that COCs containing the progestin, levonorgestrel, were associated with 20–50% lower risk of VTE than the others.9
We can conclude from these studies that the risk of VTE increases when taking a CPA-containing COC but that this risk probably is not any greater for CPA-containing COCs than for most other ones, except those containing levonorgestrel.
Controversy Surrounding Cyproterone Acetate
Despite the mixed research results, the possible increased risk of VTE in people taking a CPA-containing COC has caused controversy in several countries.
According to a 2005 article in CMAJ, a Canadian television documentary on the CPA-containing COC called Diane-35 (known as Dianette in the UK) caused many women to switch from Diane-35 to a different COC. In February 2003, there was a sharp increase in the number of women, both with and without acne, who switched to a different COC.10
According to a 2013 article in BMJ, France banned the sale of Diane-35 in May 2013 because of the risk of VTE. Shortly thereafter, the European Commission ordered France to lift the ban, and the European Union required all European countries to follow the recommendations of the European Medicines Agency, which concluded that “the benefits of Diane-35 outweighed the risks, provided measures were taken to minimize those risks.”11The European Medicines Agency concluded also that Diane-35 should be prescribed only to women who needed birth control and had moderate to severe acne or hirsutism (excess hair that grows in a male pattern, such as on the face) related to androgen sensitivity. In addition, the agency stated Diane-35 should be prescribed for acne only if all other treatments fail and that it never should be prescribed in combination with another hormonal birth control pill.11
The Bottom Line
If you are a woman with acne that hasn’t responded to other treatments, and you also want to use a birth control pill, choosing a pill that contains CPA might be a treatment option for you. Be sure to talk to your doctor about the risks and benefits of this medication.