The Food and Drug Administration (FDA) announced on Tuesday, May 31, 2011 that is would be investigating the safety and possible increased risks of developing blood clots with the use of drospirenone containing birth control pills. The increased risk of developing blood clots, medically known as deep venous thrombosis or venous thromboembolism, in women taking birth control pills is well documented in the medical literature. Smoking and age over 35 significantly increase the risk, and their use is not advised for smokers or older women. Blood clots can be a life threatening condition without proper treatment. Birth control pills usually contain an estrogen hormone and a progestin hormone. Older birth control pills used a progestin called levonorgestrel while newer pills contain a progestin called drospirenone. Drospirenone is used in popular brands such as Yaz, Yasmin, Beyaz, and Safyral. Previous studies have not shown an increased risk of developing blood clots in women who used either of the two types of birth control pills (levonorgestrel-containing versus drospirenone-containing). Recently, two studies were published in the British Medical Journal that gave evidence that the newer drospirenone-containing birth control pills had a two to three times greater chance of developing life threatening blood clots. As a result, there is now conflicting data as to the dangers of developing deep venous thrombosis or venous thromboembolism with the use of the popular drospirenone-containing birth control pills. The FDA has commissioned a large study of more than 800,000 women to investigate the possible increased risk of blood clot formation with the use of drospirenone-containing birth control pills. The data from the study should be available later this summer. In the meantime, the FDA has advised that women taking drospirenone-containing birth control pills should not stop taking them until their investigation is complete. In addition, the FDA suggests that the symptoms of blood clots should be known and includes swelling of the leg, shortness of breath, and chest pain especially with deep inspiration. The European Medicines Agency announced on May 27, 2011, that is would update product labeling to reflect the increased risk of blood clots for drospirenone-containing birth control pills, but also added that women should not stop taking drospirenone-containing birth control pills. The popularity of the newer drospirenone-containing birth control pills makes this announcement very important and will likely affect millions of women throughout the world.