Levonorgestrel tablets have no serious or lasting adverse effects, are well tolerated, safe and effective, and have been used as a contraceptive for more than 30 years. Common side effects include irregular menstruation, amenorrhea, spotting bleeding and endometrial breakthrough bleeding, etc. Rarely, headache, chest pain, weakness of limbs, numbness, mental depression, vision changes, lactation, etc. Occasionally, nausea and vomiting are seen, but the above symptoms are mild, short-lived and usually do not require treatment. Because the half-life of levonorgestrel tablets is 8.8-11h, that is to say, after about 3 days, the levonorgestrel in the blood is left 1/128, there is basically no residue in the body, so even if it is taken several times in a menstrual cycle, there will be no serious toxic side effects; on the other hand, the dose of levonorgestrel tablets is 0.75mg per tablet, and it will be taken again at an interval of 12 hours, and the total dose of one emergency The total dose of levonorgestrel is 1.5mg, which is less than half of the amount of levonorgestrel in conventional short-acting contraceptives. Levonorgestrel tablets are contraindicated in patients with diabetes, depression, hypertension, and venous thrombophilia.