The signs and symptoms of orthostatic hypotension and neurally mediated hypotension (NMH) are similar. They include:
Orthostatic hypotension may happen within a few seconds or minutes of standing up after you've been sitting or lying down.
You may feel that you're going to faint, or you may actually faint. These signs and symptoms go away if you sit or lie down for a few minutes until your blood pressure adjusts to normal.
The signs and symptoms of NMH occur after standing for a long time or in response to an unpleasant, upsetting, or scary situation. The drop in blood pressure with NMH doesn't last long and often goes away after sitting down.
In shock, not enough blood and oxygen flow to the body's major organs, including the brain. The early signs and symptoms of reduced blood flow to the brain include light-headedness, sleepiness, and confusion.
In the earliest stages of shock, it may be hard to detect any signs or symptoms. In older people, the first symptom may only be confusion.
Over time, as shock worsens, a person won't be able to sit up without passing out. If the shock continues, the person will lose consciousness. Shock often is fatal if not treated right away.
Other signs and symptoms of shock vary, depending on what's causing the shock. When low blood volume (from major blood loss, for example) or poor pumping action in the heart (from heart failure, for example) causes shock:
When extreme relaxation of blood vessels causes shock (such as in vasodilatory shock), a person feels warm and flushed at first. Later, the skin becomes cold and sweaty, and the person feels very sleepy.
Shock is an emergency and must be treated right away. If a person has signs or symptoms of shock, call 9–1–1.
The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.