Although tamoxifen is mainly used for patients with advanced ovarian cancer, or breast cancer, a day missed in the course of taking the drug often does not have much effect, but after the missed dose is found, it is necessary to make up for it in time. For patients who are already menopausal, they usually do not show menstruation in the process of taking tamoxifen, so even if they miss 3 days of dosing, the effect is not significant. For non-menopausal patients, if irregular vaginal bleeding or even heavy vaginal bleeding occurs while taking tamoxifen, then it is also necessary to suspend tamoxifen.