Vasomotor Symptoms (Hot Flashes)

Hot flashes are a rapid and exaggerated heat dissipation response consisting of profuse sweating, peripheral vasodilation, and feelings of intense internal heat. ^[1] Vasomotor symptoms (VMS) comprise hot flashes or flushes and night sweats, and they are common among women undergoing the menopausal transition. ^[2] According to an ACOG practice bulletin, VMS are the most commonly reported menopausal symptoms, with a reported prevalence of 50-82% among U.S. women who experience natural menopause. ^[3] A JAMA review estimates that approximately 50% to 75% of women have hot flashes, night sweats, or both during the menopausal transition. ^[4] The highest-quality menopause clinical practice guidelines list VMS alongside disturbed sleep, musculoskeletal pain, decreased sexual function or desire, and mood disturbance as symptoms associated with perimenopause and menopause. ^[5] Menopausal symptoms after cancer treatment, including VMS, can be more severe than at natural menopause. ^[6]

Hot flashes are triggered by small elevations in core body temperature acting within a greatly reduced thermoneutral zone, the core temperature range between the sweating and shivering thresholds. ^[1] This narrowing of the thermoneutral zone is due in part, but not entirely, to estrogen depletion at menopause. ^[1] Elevated central sympathetic activation, mediated through alpha-2 adrenergic receptors, is one factor responsible for narrowing the thermoneutral zone. ^[1] The occurrence of VMS increases during the transition to menopause and peaks approximately 1 year after the final menstrual period. ^[3] VMS are reported to typically last more than 7 years, so for many women they are a prolonged rather than a brief transitional complaint. ^[4] During female midlife, obesity has been associated with menopausal symptoms including hot flashes, although the relationships between weight, the menopausal process, aging, and hormone levels remain poorly understood.

VMS have been associated with elevated blood pressure and increased cardiovascular disease risk, an association rather than proven causation, and autonomic dysregulation of blood pressure has been posited as a contributing factor. ^[2] Women with VMS during menopause seem to have an unfavourable cardiometabolic profile, an association rather than an established causal link. ^[8] A review of menopause and cardiovascular risk notes that menopause-related symptoms such as VMS, sleep disturbances, and mood changes may have a direct impact on cardiovascular disease risk. ^[9] Hot flashes are responsible for some, but not all, of the sleep disturbance reported during menopause, which is relevant when assessing sleep complaints in midlife women. ^[1] VMS, particularly when severe or sleep-disrupting, are associated with greater vulnerability to depressive symptoms over the

The 2022 hormone therapy position statement of The North American Menopause Society states that hormone therapy remains the most effective treatment for VMS. ^[13] In the 2022 NAMS statement, the benefit-risk ratio is favorable for bothersome VMS in women younger than 60 years or within 10 years of menopause onset without contraindications, and appears less favorable when therapy starts more than 10 years from menopause onset or after age 60 because of greater absolute risks of coronary heart disease, stroke, venous thromboembolism, and dementia. ^[13] Systemic estrogen alone or combined with a progestogen reduces the frequency of VMS by approximately 75%, and oral and transdermal estrogen have similar efficacy. ^[4] The 2023 nonhormone therapy position statement of The North American Menopause Society recommends cognitive-behavioral therapy, clinical hypnosis, SSRIs/SNRIs, gabapentin, and fezolinetant (Level I evidence), oxybutynin (Levels I-II), and weight loss and stellate ganglion block (Levels II-III). ^[14] The same NAMS nonhormone statement does not recommend paced respiration, supplements or herbal remedies, cooling techniques, trigger avoidance,