For my my OI (I have POTS, orthostatic hypertension up to 197/138, orthostatic hypotension down to 40/0 or lower, narrowing of the pulse pressure to only 7. I also can get orthostatic arrthymia.. irregular heart beat when standing). The ways it can affect me (depends on which way it goes at the time) is
- feeling faint or dizzy or shaky on standing
- feeling faint, dizzy or shaky after Ive been on my feet for a little time
- feeling pale
- feeling weak or weak legs, legs can suddenly give way
- pressure feeling in my brain (as if its about to explode, I think I get that symptom when my orthostatic hypertension has kicked in)
- headache
- legs can go feeling very heavy when upright
- loss of balance
- shaking and spasming and twitching, seizure like activity (when not enough blood is getting to my brain)
- my ability to think declines (when blood isnt getting to brain
- very low (to nil dystolic which forces me to lay and it can remain at such low levels for up to that noone should ever see on a BP monitor for up to 5mins. The hospital has put monitors on both my arms as they couldnt believe what they were seeing on the monitors. I can still be speaking ok at crazy low BP levels though unable to sit) to very high BP
- blurred vision or even NIL vision (the world will go black and I completely loose my sight before some collapses)
- feeling nauseus and like im will throw up if I dont lay down
- collapse to unconsciousness (ive been unconscious according to someone for 3-5 mins after I collapsed due to being upright too long)
- swelling of my optic discs (I believe it was caused by orthostatic hypertension I had at time. This could be putting me at risk of sudden permanent blindness)
I probably get other symptoms with it too but those are just the ones I can think of right now off my head I get with it.
You should have a tilt table test done or at least a poor mans standing test done in the doctors office to try to figure out what kind/s of OI you have as treatment can be different for different kinds.