given at days three to seven of a woman's cycle. Tamoxifen improves fertility in males with infertility by disinhibiting the hypothalamic–pituitary–gonadal axis (HPG axis) via ER antagonism and thereby increasing the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and increasing testicular testosterone production. Gynecomastia Tamoxifen is used to prevent and treat gynecomastia. It is taken as a preventative measure in small doses, or used at the onset of any symptoms such as nipple soreness or sensitivity. Other medications are taken for similar purposes such as clomifene and the anti-aromatase drugs which are used in order to try to avoid the hormone-related adverse effects. Early puberty Tamoxifen is useful in the treatment of peripheral precocious puberty, for instance due to McCune–Albright syndrome, in both girls and boys. It has been found to decrease growth velocity and the rate of bone maturation in girls with precocious puberty, and hence to improve final height in these individuals. Available forms Tamoxifen is available as a tablet or oral solution. Contraindications Tamoxifen has a number of contraindications, including known hypersensitivity to tamoxifen or other ingredients, individuals taking concomitant coumarin-type anticoagulant therapy, and women with a history of venous thromboembolism (deep vein thrombosis or pulmonary embolism). Side effects A report in September 2009 from Health and Human Services' Agency for Healthcare Research and Quality suggests that tamoxifen, raloxifene, and tibolone used to treat breast cancer significantly reduce invasive breast cancer in midlife and older women, but also increase the risk of adverse side effects. Endometrial cancer Tamoxifen is a selective estrogen receptor modulator (SERM). Even though it is an antagonist in breast tissue it acts as partial agonist on the endometrium and has been linked to endometrial cancer in some women. Therefore, endometrial changes, including cancer, are among tamoxifen's side effects. With time, risk of endometrial cancer may be doubled to quadrupled, which is a reason tamoxifen is typically only used for five years. The American Cancer Society lists tamoxifen as a known carcinogen, stating that it increases the risk of some types of uterine cancer while lowering the risk of breast cancer recurrence. Cardiovascular and metabolic Tamoxifen treatment of postmenopausal women is associated with beneficial effects on serum lipid profiles. However, long-term data from clinical trials have failed to demonstrate a cardioprotective effect. For some women, tamoxifen can cause a rapid increase in triglyceride concentration in the blood. In addition, there is an