ORAL CONTRACEPTIVES CONTAINING CYPROTERONE INCREASE RISK OF DEEP VEIN THROMBOSIS: four times more likely to develop deep vein thrombosis, or venous blood clots, than those taking OCs that contain levonorgestrel.
Deep vein thrombosis can cause potentially fatal pulmonary embolism if blood clots travel through the bloodstream and lodge in the lungs. The retrospective case-control study of 24,401 women ages of 16-39, 1992-1999. Of the 26 cases and 144 controls, 14 cases and 114 controls had taken OCs with levonorgestrel, and 12 cases and 30 controls had taken OCs with cyproterone.
The analysis also showed that duration of exposure did not affect risk of venous thromboembolism after cyproterone exposure (Lancet, 10/27). Cyproterone is found in "so-called third-generation" birth control pills, which contain more progestin than older versions, such as those that contain levonorgestrel [Research letter, 27Oct01, Vasilakis-Scaramozza/Jick, (Boston Univ School of Medicine) Lancet Reuters Health, 10/26; Kaiser Daily Reproductive Health Reports, 10/29]