Mij
Senior Member (Voting Rights)
I think my case of orthostatic intolerance is caused by pooling of blood in the lower part of the body.
Possibly my experience too. My legs turn purple when I stand after taking a warm shower, I need to lie down for half an hour after to recover.
But after I go for power walks in the evenings when I'm feeling better, I can sit upright for hours after w/o any issues and can talk on the phone w/o cognitive issues. I have increased blood flow circulation to my brain.