Objective To study the influence of concomitant use of hormonal contraception and non-steroidal anti-inflammatory drugs (NSAIDs) on the risk of venous thromboembolism. Design Nationwide cohort study. Setting Denmark through national registries. Participants All 15-49 year old women living in Denmark between 1996 and 2017 with no medical history of any venous or arterial thrombotic event, cancer, thrombophilia, hysterectomy, bilateral oophorectomy, sterilisation, or infertility treatment (n=2 029 065). Main outcome measure A first time discharge diagnosis of lower limb deep venous thrombosis or pulmonary embolism. Results Among 2.0 million women followed for 21.0 million person years, 8710 venous thromboembolic events occurred. Compared with non-use of NSAIDs, use of NSAIDs was associated with an adjusted incidence rate ratio of venous thromboembolism of 7.2 (95% confidence interval 6.0 to 8.5) in women not using hormonal contraception, 11.0 (9.6 to 12.6) in women using high risk hormon