Its called heat intolerance. Its common with EDS and autonomic dysfunction. My doctors say theres not much to do about it, I'm not convinced, so I continue to look...

I have this but I have Ehlers-Danlos comorbid with PoTS so I assume mine has more to do with the PoTS than EDS. The things that help me best are making sure I've eaten something and also drank something with electrolytes before a shower. This might not help if you don't have PoTS, but it certainly couldn't hurt anything

If it becomes intolerable, you can always get a shower chair. They sell specially made ones, but you can also just use a metal or plastic folding chair. I use one, and it has helped me tremendously