Heat intolerance is a chronic feeling of being too warm when external temperatures rise. Heat intolerance often causes flushing, overheating of the skin and as excessive sweating. This condition goes beyond ordinary discomfort with heat experienced by the majority of people. It is typically caused by impaired regulation of the body’s internal temperature and is exacerbated by high external temperatures.
Amphetamines and Caffeine
Two of the most common causes of heat intolerance are amphetamine use and caffeine. Amphetamines, such as appetite suppressants, and caffeine are stimulants that increase the body’s metabolism. Increased metabolism leads to increased blood flow, which causes the skin to overheat and produces excessive sweating. As outside temperatures rise, this overheating becomes more severe, causing symptoms of heat intolerance. If you are experiencing heat intolerance, try cutting back on caffeine intake, or ask your doctor about any new prescriptions you’re taking, which might include amphetamines.
Another common cause of heat intolerance is hyperthyroidism. Hyperthyroidism is a condition caused by an overactive thyroid that produces excess thyroid hormone. Excess thyroid hormone production can cause an individual to feel constantly warm and sweaty, and often causes other symptoms including heart palpitations, weight loss, muscle weakness, and fatigue. If you are experiencing a combination of these symptoms, ask your doctor about getting checked for hyperthyroidism.
Multiple Sclerosis and Other Chronic Conditions
Many chronic conditions, including multiple sclerosis, are negatively affected by high outside temperatures. The arrival of summer can mean a worsening of symptoms, which is called pseudoexacerbation. This form of heat intolerance may not cause traditional symptoms such as overheating and excess sweat; rather, it often manifests simply as an increase in severity of symptoms usually caused by the condition.
Many women going through menopause experience heat flashes and heat intolerance. Heat flashes can range from a barely noticeable feeling of warmth to a heat increase that results in profuse sweating. Some women experience heat intolerance in addition to or in the absence of heat flashes. Heat intolerance in menopausal women typically manifests as a chronic feeling of being too warm, even in winter. However, symptoms of heat intolerance usually resolve within two years.