What would be a reason that someone does not sweat? no matter how much water they drink or exercise? i turn beat red, bad headache ... but no sweat?

Dysautonomia: This is a condition of the autonomic nervous system. Inability to sweat can lead to other conditions like over-heating. This symptom may be accompanied by other subtle symptoms. You should see a neurologist to better define the extent of your problem.

Autonomic problem: Although there are many potential causes, a common one relates to dysfunction of the autonomic nervous system (which is treatable). Autonomic dysfunction which is often seen with exposure to environmental toxins like toxic metals and toxic organic chemicals may lead to reduction or stoppage of sweating. This is not good as sweating plays a major role in toxin elimination (detox). I