Causes of Heat Intolerance

Updated March 23, 2017

Heat intolerance causes some people to feel uncomfortable when temperatures rise, and summer temperatures and areas with high humidity can exacerbate heat sensitivity. The body becomes overheated, and the person begins sweating profusely. According to the University of Maryland Medical Center, the condition often develops slowly and lasts a long time. Heat intolerance can result from hormonal changes, health problems and the consumption of certain stimulants.

Symptoms of Heat Intolerance

Symptoms of heath intolerance include blurred vision when overheated, fatigue, tremors and memory problems, according to the Multiple Sclerosis Resource Centre. Other symptoms are dizziness, fainting, heart palpitations, elevated heart rate and vomiting. Call your doctor if you think you are heat intolerant. The doctor will conduct a physical examination, including a blood and thyroid test, and document your medical history.

Drugs and Caffeine

Drugs and caffeine are two common causes of heat intolerance. The Consumer Health Information Corporation says they interfere with the body's natural ability to regulate its temperature. These drugs increase blood flow, causing the skin to overheat and sweat. Medications that lead to heat sensitivity include allergy medications, psychotropic drugs, tranquillisers, recreational drugs and medication for high blood pressure. Caffeine in medications and beverages like coffee and tea can also cause heat intolerance and cause fluid loss and muscle cramps, according to Texas A&M Family and Consumer Sciences.

Thyroid Conditions and Multiple Sclerosis

Health conditions that cause heat intolerance include thyroid problems and multiple sclerosis. According to MedlinePlus, one of the symptoms of thyrotoxicosis is sensitivity to heat. This condition results in an overproduction of thyroid hormone. Health problems that cause overactive thyroids are Graves disease, inflammation from viral infections and tumours on reproductive organs. Heat intolerance from multiple sclerosis occurs because the sheath that protects nerve fibres breaks down, causing nerve signals to malfunction. The Multiple Sclerosis Resource Centre states that heat sensitivity does not cause permanent damage.


Menopause causes heat intolerance because of hormonal changes in the body. The body stops producing eggs, and progesterone and oestrogen levels decrease. A person may experience hot flushes, night sweats and warm skin. Treatments include hormone replacement therapy and lifestyle changes like reducing alcohol, spicy foods and caffeine consumption.

Managing Heat Intolerance

Lifestyle changes can help manage heat intolerance, including drinking lots of water to avoid dehydration, eating ice pops, staying inside during the warmer time of the day and using personal misters and cooling sprays. Persistent conditions may require medical intervention.

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About the Author

Based in Tucson, Ariz., Cicely A. Richard has been writing since 1996. Her articles have been published in the “Arizona Daily Star” newspaper and “ForeWord Magazine.” Richard earned Bachelor of Arts degrees in English and journalism from Louisiana State University. .