Menopause is the time when menstrual periods permanently stop, marking the end of the reproductive stage for the female human. It typically occurs between the ages of 45 and 55, although the exact timing can vary. Menopause is usually a natural change related to a decrease in circulating blood estrogen levels. It can occur earlier in those who smoke tobacco. Other causes include surgery that removes both ovaries, some types of chemotherapy, or anything that leads to a decrease in hormone levels. At the physiological level, menopause happens because of a decrease in the ovaries' production of the hormones estrogen and progesterone. While typically not needed, measuring hormone levels in the blood or urine can confirm a diagnosis. Menopause is the opposite of menarche, the time when periods start.

In the years before menopause, a woman's periods typically become irregular, which means that periods may be longer or shorter in duration, or be lighter or heavier in the amount of flow. During this time, women often experience hot flashes; these typically last from 30 seconds to ten minutes and may be associated with shivering, night sweats, and reddening of the skin. Hot flashes can recur for four to five years. Other symptoms may include vaginal dryness, trouble sleeping, and mood changes. The severity of symptoms varies between women. Menopause before the age of 45 years is considered to be "early menopause", and ovarian failure or surgical removal of the ovaries before the age of 40 years is termed "premature ovarian insufficiency".

In addition to symptoms (hot flushes/flashes, night sweats, mood changes, arthralgia and vaginal dryness), the physical consequences of menopause include bone loss, increased central abdominal fat, and adverse changes in a woman's cholesterol profile and vascular function. These changes predispose postmenopausal women to increased risks of osteoporosis and bone fracture, and of cardio-metabolic disease (diabetes and cardiovascular disease).

Medical professionals often define menopause as having occurred when a woman has not had any menstrual bleeding for a year. It may also be defined by a decrease in hormone production by the ovaries. In those who have had surgery to remove their uterus but still have functioning ovaries, menopause is not considered to have yet occurred. Following the removal of the uterus, symptoms of menopause typically occur earlier. Iatrogenic menopause occurs when both ovaries are surgically removed (oophorectomy) along with the uterus for medical reasons.

Medical treatment of menopause is primarily to ameliorate symptoms and prevent bone loss. Mild symptoms may be improved with treatment. With respect to hot flashes, avoiding nicotine, caffeine, and alcohol is often recommended; sleeping naked in a cool room and using a fan may help. The most effective treatment for menopausal symptoms is menopausal hormone therapy (MHT). Non-hormonal therapies for hot flashes include cognitive-behavioral therapy, clinical hypnosis, gabapentin, fezolinetant or selective serotonin reuptake inhibitors. These will not improve symptoms such as joint pain or vaginal dryness, which affect over 55% of women. Exercise may help with sleeping problems. Many of the concerns about the use of MHT raised by older studies are no longer considered barriers to MHT in healthy women. High-quality evidence for the effectiveness of alternative medicine has not been found.

During early menopause transition, the menstrual cycles remain regular but the interval between cycles begins to lengthen. Hormone levels begin to fluctuate. Ovulation may not occur with each cycle.

The term menopause refers to a point in time that follows one year after the last menstruation. During the menopausal transition and after menopause, women can experience a range of symptoms. However, for women who enter the menopause transition without having regular menstrual cycles (due to prior surgery, other medical conditions or ongoing hormonal contraception) the menopause cannot be identified by bleeding patterns and is defined as the permanent loss of ovarian function.

During the transition to menopause, menstrual patterns can show shorter cycling (by 2–7 days); longer cycles remain possible. There may be irregular bleeding (lighter, heavier, spotting). Dysfunctional uterine bleeding is often experienced by women approaching menopause due to the hormonal changes that accompany the menopause transition. Spotting or bleeding may simply be related to vaginal atrophy, a benign sore (polyp or lesion), or may be a functional endometrial response. The European Menopause and Andropause Society has released guidelines for assessment of the endometrium, which is usually the main source of spotting or bleeding.