Cochrane Summaries

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Contraceptive pills and venous thrombosis

de Bastos M, Stegeman BH., Rosendaal FR., Van Hylckama Vlieg A, Helmerhorst FM, Stijnen T, Dekkers OM
Published Online: 
3 March 2014

Contraceptive pills are among the most popular contraception methods worldwide. A combined oral contraceptive pill contains two components, the estrogen and the progestagen compound. Despite its reliable contraception action, these pills may present side-effects including obstruction of leg and pulmonary vessels by clots (venous thrombosis). This side-effect is rare but the most frequently occurring serious adverse effect. Different combination pills show different vessel clotting obstruction tendencies (venous thrombosis risk). Evaluation of these different tendencies may play an important role in choosing the safest pill when starting pill use. COC containing higher estrogen doses (>30 μg) with levonorgestrel (a progestagen) or containing cyproterone acetate or drospirenone as progestagen are associated with higher VT risk than the oral contraceptive pill with 30 μg estrogen and levonorgestrel as progestagen. All combined monophasic oral contraceptive pills have the same effectiveness, that is preventing unwanted pregnancies.