What is heat syncope?

• A. Fainting due to heat
• B. Heat rash
• C. Heat exhaustion
• D. Heat stroke

Answer: (A)

Heat syncope is fainting caused by heat exposure. It occurs when the body dilates blood vessels to shed heat, causing blood to pool in the skin and legs. This reduces the amount of blood returning to the heart and, consequently, the brain, leading to a brief loss of consciousness. You often see it after standing for long periods or when moving quickly from a hot environment to a cooler one. The episode is typically short and resolves with lying down, cooling, and hydration.

This is distinct from heat exhaustion, which involves fatigue, dizziness, sweating, weakness, and thirst without a fainting spell, and from heat stroke, where the person experiences confusion or other mental status changes and a markedly elevated core temperature requiring emergency care. Heat rash is simply a skin irritation from sweating.