I hav very bad heat intolerance to the point where i will completely pass out.what could this be a sign of?had it all my life.wat causes such sensitiv

2 thoughts: The three thoughts that come to mind are: are you overweight ?(which causes heat intolerance) and have you had your thyroid checked? And do you sweat? Disorders of any of these 3 would cause heat intolerance.

Possible dysautonomi: You have syncope and in the setting of heat intolerance could be a sign of dysautonomia or pots. Other common symptoms include postural intolerance, palpitations, fatigue, headaches, shortness of breath. Therapy options are available and could be discussed with a specialist.