Blood clot risk increases with anti-androgen pill - study

Taking anti-androgen contraceptive pills increases the risk of getting blood clots, a New Zealand study has found.

Richard Beasley, director of the Wellington-based Medical Research Institute, said today using Diane-35 and Estelle-35 contraceptives increases the risk of clots leading to deep vein thrombosis (DVT) and pulmonary embolism.

The risk was similar to that of "third generation" pills, which are recognised to increase the risk of clots, Professor Beasley said.

The findings supported Health Ministry advice to doctors that use of the pills should be limited.

Diane-35 and Estelle-35 are popular in New Zealand because they also reduce acne and facial hair in women, caused by male hormones (androgens), he said.

The risk of clots increases with age and is affected by which pill women take.

Of the 100,000 taking the pill every year, about 35 women will develop a clot and one will die.

The odds of getting a clot increased by three to four times for women taking second generation pills and six to eight times for third generation or anti-androgen pills compared with women who take no contraceptive pill.

Women taking progesterone-only pills are at little risk of clots.

The findings were reassuring because it confirmed the relative safety of second generation pills, Prof Beasley said in a statement.

The study, published today in the New Zealand Medical Journal, was undertaken by the institute, Auckland's Green Lane Hospital, Wellington School of Medicine and Health Sciences, drug-funding body Pharmac and Southampton University in England.

- NZPA