Hormone replacement therapy. Two patches used in hormone replacement therapy (HRT). HRT uses synthetic drugs to treat hormone deficiency in menopausal women. It helps prevent osteoporosis, atherosclerosis and atrophic vaginitis (thinning and dryness of the vagina). Both the patches contain combinations of the hormones oestradiol and norethisterone acetate. The patch is applied to the skin, and it releases the hormones into the bloodstream in a slow and controlled fashion. Adverse effects include nausea, tenderness of the breasts, fluid retention and leg cramps. There is also a greater risk of developing uterine cancer when taking oestrogen drugs.