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Does the thought of summer’s high temperatures make you a little queasy? Does that feeling get worse when you step into the scorching summer sun? It could be heat intolerance.


What are the symptoms of heat intolerance?

Heat intolerance is also called heat hypersensitivity. It happens when your body does not regulate its temperature correctly and cannot maintain a balance between cold and hot. Heat intolerance causes a more extreme reaction than many people's discomfort when temperatures rise.

Common symptoms include:

  • Excessive fatigue
  • Headaches
  • Mood changes
  • Muscle cramps or weakness
  • Nausea and vomiting
  • Rapid heartbeat
  • Sweating too much or not at all


What causes heat intolerance?

Heat intolerance is not an illness on its own. It is a term used to refer to a wide range of responses to heat. Some forms may not be fully treatable or preventable—depending on their cause.



You are more likely to be affected by the heat if you are older than 65, according to the Centers for Disease Control and Prevention (CDC). Older bodies do not constantly adjust to sudden temperature changes quickly or easily. And older adults are more likely to have an underlying medical condition or are on medication that affects their temperature control.


Chronic Medical Conditions

Some chronic medical conditions may make you more prone to heat intolerance, including:

  • Heart disease
  • Hyperthyroidism and Graves’ disease
  • Mental illness
  • Multiple sclerosis
  • Obesity

The reasons for this vary. Several chronic health conditions reduce your body’s ability to regulate its internal temperature. Others restrict how well you respond to extreme heat and temperature changes in the weather. For some people, the medication required to treat their medical issues also causes heat tolerance issues.



Some prescription and over-the-counter medications can trigger heat intolerance, including:

  • Allergy medications such as antihistamines or decongestants
  • Antibiotics
  • Antidepressants and antipsychotics
  • Blood pressure medication
  • Diabetes medication
  • Overactive bladder medication
  • Pain relievers 

Talk to your physician if you regularly take medication and experience heat-related health issues to determine if the two are linked.


How can I protect myself from heat intolerance?

Minimize your risk of having an adverse reaction to summer’s higher temperatures with these tips:

  • Monitor your medications. Side effects from drugs and dietary supplements can often be overlooked when determining the cause of your heat intolerance. Talk to your physician if you have any questions or concerns.
  • Plan to stay cool. Limit your outdoor activities to the early morning or later evening when it is not as hot outside. Stay in an air-conditioned room when the temperatures reach “furnace levels” of heat.
  • Stay hydrated. Be sure to get enough fluids when summer's heat makes dehydration possible—especially if you are taking diuretics or other medications that affect your hydration level.
  • Stick to the shade. Avoid being outdoors or staying in the shade when the sun’s rays peak.


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