Heat exhaustion is best characterized by

• A. Exercise intolerance, increased core body temperatures, and the absence of neurologic disturbances
• B. Severe hyperthermia with altered mental status
• C. Extreme dehydration with hypotension and coma
• D. Fever with seizures

Answer: (A)

Heat illness exists on a spectrum, and telling them apart hinges on how the brain is affected and how hot the body gets. Heat exhaustion is driven by heat exposure and dehydration, leading to fatigue and an inability to tolerate exertion. The body’s core temperature can be elevated, but there are no neurologic disturbances. That combination—exercise intolerance with a rising core temperature and no CNS signs—fits heat exhaustion best.

In contrast, heat stroke shows severe hyperthermia with clear central nervous system involvement, such as confusion, agitation, seizures, or coma, and it requires urgent, aggressive cooling. The other scenarios describe conditions with CNS effects or fever from another cause, which are not characteristic of heat exhaustion.