Postural orthostatic tachycardia syndrome - Wikipedia

What could cause a person to feel dizzy or lightheaded when

Whenever I get up after sitting for 15 minutes, I get really dizzy

Why do I get really dizzy/nauseous after getting up after sitting

Why does my 11 year old sister frequently faint in school? 2 times

Dysautonomia - Titronics Research & Development, Inc

If my friend had a sudden blackout episode but blood pressure was

Why do I get really dizzy/nauseous after getting up after sitting down

Can you get dizzy from standing up too fast if you've been sitting

Research and Knowledge - Titronics Research & Development, Inc

Why does my 11 year old sister frequently faint in school? 2 times

Dysautonomia - Titronics Research & Development, Inc

If my friend had a sudden blackout episode but blood pressure was