10/20/2026
Standing up is a small circulatory event. Gravity pulls blood into the lower body, and the system has to push it back up so the brain and other organs stay supplied.
There are a few ways that compensation can fail, and the differences between them are what separate these diagnoses.
In POTS, the heart rate goes up and stays up. The usual reason is that blood vessels in the lower body aren’t constricting the way they should, so blood pools there, and the heart compensates by beating faster to move it upward.
The detail that distinguishes POTS is blood pressure. It often doesn’t change at all, and in some cases, it rises slightly. The tachycardia is doing the work of holding perfusion steady.
Orthostatic hypotension looks different on the cuff. Standing up produces a blood pressure drop.
The underlying causes can overlap considerably, which is why some of the treatments do too. Both can involve lower-body blood vessels that fail to compensate, and both can involve inadequate fluid volume in the system.
Same trigger, different failure, different numbers on standing.