DVT Warning for Contraceptive Pill users
Safety of the contraceptive pill is again being questioned, sparked by the news that an Adelaide based law firm may be launching a class action on behalf of women taking the combined contraceptive pill who have suffered from deep venous thrombosis (clots in the legs). The action may be against a pharmaceutical manufacturer of one of these pills. The fact is that all combined oral contraceptive pills increase the risk of deep venous thrombosis (‘DVT’) by an overall factor of three to four times the risk (ie if not taking the pill), as determined by a recent Cochrane review of 25 publications. Despite this, the risk remains low overall. The lowest risk of clots from combined pills lies with pills containing 30 μg or less of oestrogen and with levonorgestrel as the progestagen. Conversely, pills with a greater amount of oestrogen or progestagen other than levonorgestrel have a higher incidence (50% to 80% higher) of causing clots. Progestagens other than levonorgestrel include drospirenone (marketed as Yaz or Yasmin), gestodene (Minulet), desogestrel (Marvelon) and cyproterone acetate (Estelle/Juliet/Dianne/Brenda) were similar in their increased risk, and about 50-80% higher than with levonorgestrel. The risk is still quite low, eg on average a clot would not occur until taking the combined pill continuously for more than 1000 years (if one was to live that long!). Immobilisation is a key risk factor for DVT. Family history also plays a role. The minipill, aka the progesterone only pill, avoids increasing the risk of DVT, but has limitations in comparison with the combined pill.