After taking kynurenine tablets for 20 days and stopping the drug, it usually takes 2-7 days before menstruation, depending on the person, not a generalization. Norethindrone tablets will not come to menstruation immediately after stopping taking them for 20 days, and it usually takes about 2-7 days for menstruation to come after stopping norethindrone tablets. If you don’t have your period for more than 7 days, you need to consult a doctor to rule out the possibility of pregnancy, and you also need to rule out the lack of menstruation caused by the decline of ovarian function. Norethindrone tablets are used for contraception, but can also treat dysfunctional uterine bleeding, menstrual irregularities, endometriosis. It is contraindicated for those who are allergic to norethindrone tablets, and allergy sufferers and first-time patients should be alert to the occurrence of allergy. The drug is contraindicated in patients with severe liver and kidney disease, breast lumps to avoid danger. The main side effects of the drug are nausea, dizziness and tiredness. Therefore, if you don’t have a period even 7 days after stopping the use of kynurenine tablets, it is important to consult a doctor in time to find out the cause and treat the cause.