You should see a doctor.<br />
Your body may not be regulating it's own core temperature correctly, or you could even be having circulatory problems.<br />
You should not be getting sick from simple heat.
If you afford a doctor then you should consult one. It could be nothing or a symptom for something serious. So its better to check it out.
I and my mom have this problem. It's probably low blood pressure. Heat can cause blood vessels to dilate, which lowers blood pressure and can result in feeling faint, or actual fainting.
I get that too - feeling nauseous. I think it goes with the fainting part. I see black spots, feel sick to my stomach, things start to spin and I realize I'm about to black out.
You're probably dehydrated. Drink more water.
I have the same problem with the shower. I get really light headed. Like I could hardly walk. But once I get out of the heat in the bathroom & drink some water, I'm all better. I love my hot showers tho.
My daughter has the problems that you've mentioned, she passes out when the weather gets warm. She is also intolerant of exercise and lost quite a bit of weight because she had no appetite and was vomiting quite often. After a few years back and forth to the doctors she was diagnosed with POTS (postural orthostatic tachycardia syndrome), it's very uncommon and extremely debilitating. I'd put a link to some info but I don't know how to do that, definitely look into it though (there's also a group on EP with POTS).
I have this trouble but not with showers. I absolutely can not submerge myself in a bath tub for more than 5 minutes.
Stay cool? Sounds stupid, but hot water or weather I think raises your blood pressure, causing lightheadedness. At the least it causes your cappilaries to try and rush blood to the skin surface in an attempt to cool you.
I say stay out of hot showers,hot days and hot tubs as much fun as hot tubs can lol
turn it down to warm it dose a beter job.i get the same problem in the summer when it,s over 30c or 90f go for 20 c or 80,f
Adjust for a warm shower