5. An intense, throbbing headache
Another symptom that is often associated with heatstroke is an intense, throbbing headache. The headache can come on suddenly and be debilitating. The more time you spend in the sun or exposed to heat, the worse the headache will become. Why does heatstroke cause a headache? It has to do with dehydration.
The hotter your temperature is, the more water your body loses, and that water comes out in sweat. In addition to losing water, your body also loses electrolytes when you sweat, which also leads to dehydration. As a result, blood vessels narrow and the supply of oxygen and blood to your brain is reduced, which can cause an excruciating headache. On top of a throbbing headache, dehydration can also cause dryness in the mouth and listlessness. If you experience a headache when exposed to heat, you could be suffering a heat stroke.