Ongoing concerns regarding climate change have increased questions regarding the potential for differences between men and women in the risk of heat illness during exertional heat stress.  Interestingly, autonomic control mechanisms contributing to the regulation of body temperature and the regulation of arterial blood pressure have significant overlap in humans.  This includes central autonomic control in the hypothalamus as well as peripheral control of blood flow.  Mechanisms by which estradiol affects central and peripheral autonomic mechanisms result in conditions that favor both heat dissipation and lower arterial pressure.  This is likely an adaptive effect in terms of maintaining low / normal resting blood pressure – that is, young women are less likely to become hypertensive compared to men.  Similarly, conditions of high estradiol are often associated with increased heat dissipation (sweating / skin blood flow) and lower body temperature.  However, conditions favoring lower blood pressure and increased skin blood flow can decrease orthostatic tolerance – which can also contribute to collapse in the heat.  Menopause is associated with higher resting blood pressure and increased risk of hypertension.  Older people also have increased risk of heat illness due to changes in thermoregulatory mechanisms, which, in women, are in part due to loss of circulating reproductive hormones.  Some of the overlapping mechanisms associating estradiol with lower blood pressure and lower body temperature include beta-adrenergic receptors on peripheral blood vessels and increased nitric oxide-mediated vasodilation.  Practical implications for women in a range of occupational settings are currently being investigated, including influences of common types of contraception which provide varying concentrations of exogenously administered estrogens and/or progestins.