Cayokay is correct, at least according to everything I've heard.

Before MRI's, they used to dip us in hot baths to see if that would stimulate symptoms, so I'm guessing a lot of people do have problem with heat. Perhaps that symptom tends to become more apparent the longer we've had the disease too . . . but people are getting dx much earlier these days.

I've never heard heat causes "permanent" damage, but it may trigger symptoms for some people. My symptoms always let up let up when I cool off though . . . so I'd be surprised if we need to be concerned beyond that.

Cherie