Tamoxifen blocks the actions of estrogen, a female hormone. Certain types of breast cancer require estrogen to grow._x000D__x000D_ Tamoxifen is used to treat some types of breast cancer in men and women. It is also used to lower a woman’s chance of developing breast cancer if she has a high risk (such as a family history of breast cancer)._x000D__x000D_ Tamoxifen may also be used for purposes not listed in this medication guide._x000D__x000D_ _x000D__x000D_ What is the most important information I should know about Tamoxifen citrate?_x000D__x000D_ Although tamoxifen reduces the risk of breast cancer, it may increase the possibility of developing endometrial (uterine) cancer. Women should notify their physician immediately if they develop abnormal vaginal bleeding, experience changes in vaginal discharge, or feel an increase in pelvic pain or pressure._x000D__x000D_ Tamoxifen may also cause other types of cancer in addition to uterine cancer._x000D__x000D_ Tamoxifen may cause women to develop noncancerous changes in their uterus. These include endometriosis, fibroids in the uterus, menstrual cycle irregularities, or the absence of menstrual periods._x000D__x000D_ Have regular gynecology checkups (“”female exams””), breast exams, and mammograms. Your doctor will tell you how often. These will check for signs of breast cancer and cancer of the endometrium (lining of the uterus)._x000D__x000D_ Tell all your doctors you see that you are taking tamoxifen._x000D__x000D_ Tamoxifen may increase the chances of developing a blood clot in the lung or in the leg._x000D__x000D_ Tamoxifen may increase the chance of developing liver cancer and liver abnormalities such as hepatitis._x000D__x000D_ Tamoxifen may cause eye problems. These include vision changes, damage to the retina of the eye, clots within the blood vessels of the eye, and cataracts._x000D__x000D_ Pay close attention to your body since Tamoxifen may cause serious side effects. Tell your doctor right away if you have any new breast lumps._x000D__x000D_ _x000D__x000D_ Menstruation is suppressed in a proportion of premenopausal women receiving tamoxifen for the treatment of breast cancer._x000D__x000D_ _x000D__x000D_ Tamoxifen is antiestrogen, produced for the reason of breast cancer in women because of high estrogenic amounts in there adipose tissues. For male athletes it was used for the primarily reason to stop the effect of conversion into estrogen causing gynecomastia. The structure of estrogen is very similar to testosterone, since it can aromatize many anabolic steroids is why the buildup of estrogens can be very serious concern. Estrogen can do two things negatively in males one is the extra build of fat, secondly being the extra water retention buildup in the body.Also it can increase production of FSH (follicle stimulating hormone) and LH (leutinizing hormone) in the male body. Activating the estrogen receptor can have a positive effect on HDL (good) cholesterol values._x000D__x000D_ A small number of cases of endometrial hyperplasia, endometrial polyps and an increased incidence of endometrial cancer and uterine sarcoma (mostly malignant mixed Mullerian tumours) have been reported in association with tamoxifen treatment. The underlying mechanism is unknown, but may be related to the oestrogen-like effects of tamoxifen._x000D__x000D_ Any patients receiving or having previously received tamoxifen who report abnormal gynaecological symptoms, especially vaginal bleeding including menstrual irregularities, post-menopausal bleeding and vaginal discharge, should be promptly investigated._x000D__x000D_ Nonetheless, the possibility that tamoxifen may also affect the development of endometrial pathology, including neoplasia, should be kept in mind when designing treatment regimes._x000D__x000D_ Investigations in different in vivo and in vitro systems have shown that tamoxifen has a genotoxic potential following hepatic activation. Gonadal tumours in mice and liver tumours in rats receiving tamoxifen have been reported in long term studies. The clinical relevance of these findings has not been established._x000D__x000D_ A number of second primary tumours, occurring at sites other than the endometrium and the opposite breast, have been reported in clinical trials, following treatment of breast cancer patients with tamoxifen. No casual links have been established and the clinical significance of these observations remains unclear._x000D__x000D_ In delayed microsurgical breast reconstruction, tamoxifen may increase the risk of microvascular flap complications._x000D__x000D_ In the literature it has been shown that CYP2D6 poor metabolisers have a lowered plasma level of endoxifen, one of the most important active metabolites of tamoxifen (see section 5.2)._x000D__x000D_ Concomitant medications that inhibit CYP2D6 may lead to reduced concentrations of the active metabolite endoxifen. Therefore, potent inhibitors of CYP2D6 (e.g. paroxetine, fluoxetine, quinidine, cinacalcet or bupropion) should whenever possible be avoided during tamoxifen treatment (see sections 4.5 and 5.2).