Taking birth control pills will increase the risk of blood clots, but there are many reasons for blood clots, and it is not true that taking birth control pills will definitely cause blood clots, but long-term use of birth control pills may cause blood clots. Because birth control pills basically contain estrogen, estrogen promotes collagen adhesion in the blood as well as coagulation factors are more sensitive, which will cause an increase in blood viscosity, slow down the blood flow, and then make the blood coagulation, so long-term oral contraceptive pills will contribute to the formation of blood clots. Regular monitoring of blood coagulation status is necessary when using birth control pills, and it should not be used by people with abnormal liver function. Short-acting contraceptives are contraindicated for women with abnormal lipid metabolism or previous thrombotic disease. Women of childbearing age who need contraception are advised to choose other methods of contraception that do not have side effects, such as condoms, birth control rings, etc., which can reduce the risk of thrombosis. If a woman has any discomfort while taking birth control pills, she should go to the hospital in time for a clear diagnosis by the doctor and cooperate with the doctor for symptomatic treatment.