The option that is not an early sign of heat illness is usually a flushed face (hot, very red, often dry skin), because this tends to appear later and is more associated with more severe heat illness or heat stroke, not the early, warning-stage symptoms.

Early signs of heat illness

Common early signs of heat illness (heat exhaustion and milder heat-related problems) include:

  • Dizziness or lightheadedness
  • Headache
  • Excessive sweating with cool, pale or clammy skin
  • Nausea or feeling sick
  • Muscle cramps
  • Weakness, fatigue, or feeling unusually tired
  • Thirst

These are the “warning” symptoms that appear before dangerous heat stroke develops.

Why flushed face is not early

A flushed, very red face is more typical of:

  • Later or more severe heat illness, especially when the body temperature is higher
  • Heat stroke, where skin may be hot and red and sweating can decrease

In contrast, early heat illness is usually marked by heavy sweating and skin that is cool and pale or clammy, not prominently flushed.

TL;DR: If the choices are dizziness, headache, flushed face, and excessive sweating, the one that is not an early sign of heat illness is flushed face. Information gathered from public forums or data available on the internet and portrayed here.