Despite a few tough years in the media and in research studies, hormone replacement therapy remains the most effective treatment for the hot flashes and vaginal discomfort which are characteristic of menopause. So how does it work? In the years prior to and during menopause, a woman's ovaries slowly begin decreasing production of the hormones estrogen and progesterone. Inadequate levels of these hormones are the cause of most menopausal symptoms. Hormone replacement therapy, or HRT, restores these hormonal levels, therefore causing a reduction in symptoms. There are two types of HRT. The first, estrogen-only therapy, is recommended ONLY for women who have undergone a hysterectomy, which is the surgical removal of the uterus. Although studies have found that estrogen-only therapy carries fewer risks of serious side effects, it should NOT be taken by women who have not had a hysterectomy. This is because the estrogen-only treatment can increase the risk of endometrial malignancy, or cancer of the uterine lining. Women with intact uteruses are advised to take combined hormone therapy, which adds the hormone progesterone to an estrogen regimen. The addition of progesterone to estrogen therapy is vital because this hormone promotes the sloughing of the uterine lining each month, thereby reducing the risk of endometrial cancer. Regardless of which type of HRT your doctor prescribes for you, you'll have many options for how the hormone is administered. The most common form is taken orally as a pill. Some tablets, like Prempro, combine estrogen and progesterone in a single pill, while others contain estrogen OR progesterone only. Women who prefer an alternative to pills may choose a transdermal patch, which delivers hormones gradually through the skin over several days. The patch can be placed on hidden areas such as the hips and buttocks, and the placement can be rotated with each change. Some estrogen therapy products, such as the vaginal ring, are inserted directly into the vagina and release hormones gradually for about three months before replacements are necessary. One brand of vaginal ring, called Estring, produces local effects only, meaning that it treats vaginal symptoms alone. Another form, Femring, alleviates hot flashes as well as vaginal discomfort. Creams and tablets are also inserted directly into the vagina to relieve localized symptoms. These contain estrogen alone, however, and thus are ineffective for relief of hot flashes. For this reason, women who have not undergone hysterectomy generally need to add a progesterone pill to complete their treatment. Whichever form of HRT you choose, it is vital to follow your doctor's instructions precisely, and to take the hormones only for the time prescribed. Hormone replacement therapy is a very individualized treatment. If you're experiencing symptoms of menopause and are interested in hormone supplementation, please speak with your doctor.