Currently, small doses of aspirin are often used to prevent blood clots. This is because aspirin can reduce the synthesis of thromboxane A2, thus reducing the aggregation of platelets and preventing the formation of blood clots. In human blood, the life span of platelets is about 7-14 days, and 10% of fresh platelets are produced every day. If more than 20% of platelets are not inhibited, blood clots will be formed normally, so as soon as aspirin is stopped for more than two days, the anti-platelet effect disappears, so aspirin is needed to be taken continuously every day.