Face rash, occurred after sweating in humid envr. spread all over face and neck. raised, little red nodules, have substance in them.

Prickly heat: Prickly Heat Rash or simply HEAT RASH. solution reduce exposure to extreme heat, reduce sweating. STAY COOL. Take cold showers.

Heat Rash?: The only way to be know for sure, is to have your rash looked at by a doc. However, the rash you describe is likely from the heat and is either an irritant or a minor skin infection of the hair follicles. Wash it well with soap and water to see if is would clear in a day or so. If not check it out with your doc.