Long COVID Atlas
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Plain-language first, with specialist detail below. For understanding, not medical advice.

Long COVID Atlas › Glossary › Orthostatic intolerance

Autonomic

Orthostatic intolerance

https://longcovidatlas.org/glossary/orthostatic-intolerance

In plain language

What it is

Feeling dizzy, lightheaded, or foggy when you stand up or stay upright.

Why it matters

It is one of the most common and limiting symptoms in long COVID dysautonomia.

Think of it like

The body failing the small stress test that standing represents.

What standing up does Lying downheart rate about 72,blood spread evenly stand up Standingblood pools in the legs;to compensate the heartraces 30+ beats faster POTS = the racing heart on standing;orthostatic intolerance = dizzy, foggy, faint upright
Standing is a small cardiovascular stress test. Gravity pulls blood into the legs, and the body must tighten vessels and adjust heart rate to keep the brain supplied. When that reflex misfires, the heart compensates by racing (POTS) and the brain is briefly under-supplied, felt as dizziness, lightheadedness, and fog on standing.

For specialists

Formal definition

Symptoms on upright posture from impaired cardiovascular autonomic regulation, with or without the heart-rate criteria for POTS.

Mechanism

Blood pooling and blunted compensatory reflexes reduce cerebral perfusion on standing.

Sources

Related terms

POTSDysautonomia