Which sign is characteristic of heat stroke but not heat exhaustion?

• A. Not sweating
• B. Sweating
• C. Normal mentation
• D. Temperature below normal

Answer: (A)

A key distinction between heat stroke and heat exhaustion is the status of sweating. In heat exhaustion, the body still sweats to help cool itself, and mental status is usually intact. In contrast, heat stroke involves a failure of the body's thermoregulation, leading to very high body temperature and often little or no sweating (anhidrosis). The lack of sweating makes heat stroke more dangerous because the body can overheat rapidly, and mental status is typically altered (confusion, agitation, or even seizures). So, not sweating is the sign that points to heat stroke rather than heat exhaustion. Sweating would be more typical of heat exhaustion, normal mentation would be unlikely in heat stroke, and a temperature below normal would not match the hyperthermia seen in heat stroke.