Heat Intolerance (Uhthoff's Phenomena)

Many people with MS experience sensitivity to increased body temperature. Demyelinated fibers in the central nervous system can be very sensitive to even small elevations of core body temperature resulting in conduction delays or even conduction block. This sensitivity can be brought out by sunbathing, exercise, hot baths, emotion, fatigue, fever, or any other factor associated with an increase in body core temperature. Any MS symptom can present this way.


Symptoms disappear with rest and cooling.

Avoidance is the best defense, and when unavoidable, minimum exposure followed by cooling strategies should be sought. Generally the effects of heat exposure are reversed with rest and cooling and do not carry a long term consequence. A number of manufacturers make cooling vests, hats, etc. The following is a suggested list of manufacturers and suppliers of "cooling” clothing. These links are provided for your interest only – the MS Society does not endorse any supplier or manufacturer.

Key Healthcare Professionals

  • Neurologist
  • MS nurse
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