The perimenopausal hot flash: epidemiology, physiology, and treatment

The "hot flash" (HF), or vasomotor instability, is experienced by 75% of perimenopausal and menopausal women in the United States. The experience for some women is a minor annoyance but for others, the HF is an intensely unpleasant sensation that is disruptive to their lives. The HF is thought to be triggered by a number of external and internal stimuli such as anxiety, stress, ambient high temperatures, caffeine, and alcohol. The thinner woman tends to experience more severe and frequent HFs than the woman with more adipose tissue, probably because of the ability of adipose tissue to transform androstenedione to estrone and estradiol. Smoking history also tends to be associated with the experience of HFs at an earlier age. The etiology of HFs in the decreasing estrogen state is related to the downward resetting of the hypothalamic thermoregulating mechanism, probably by the action of norepinephrine, which is usually modulated by estrogen. The body attempts to dissipate unwanted body heat by vasodilation, thus causing the sensation of the HF. The most successful treatment modalities have been hormone replacement therapy with estrogen and progesterone. Alpha 2-adrenergic blockers have also shown some limited effectiveness. Many alternative therapies such as vitamin E, primrose oil, dong quai, and black cohash have anecdotal support but have not been thoroughly studied. Relaxation, exercise, avoidance of triggering factors, and control of external environment have all been utilized with some success by women.