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Near-Fainting: Vagal Reaction

Fainting (syncope) is a temporary loss of consciousness ("passing out"). This occurs when there is reduced blood flow to the brain. Your episode may from a common vagal reaction. A vagal reaction is a reflex response that causes a sudden drop in your blood pressure, and your pulse to slow down. If the pulse is low enough, the blood pressure falls and causes fainting or near-fainting. Lying down usually stops the reaction very quickly.

This reflex response can occur during sudden fear, severe pain, emotional stress, overexertion, or suddenly standing up after sitting or lying for a long time.

Signs and symptoms

The following are symptoms of near-fainting:

  • Feeling lightheaded or like you are going to faint

  • Weak pulse

  • Nausea

  • Sweating

  • Blurred vision

  • Palpitations

  • Chest pain

  • Trouble breathing

  • Cool and clammy


Causes for near-fainting include:

  • Sudden emotional stress like fear, pain, panic, sight of blood

  • Straining or overexertion, straining while using the toilet, coughing, sneezing

  • Standing up too quickly, or standing up for too long a time

  • Pregnancy

Home care

The following will help you care for yourself at home:

  1. Rest today and go back to your normal activities as soon as you are feeling back to normal.

  2. If you become light-headed or dizzy, lie down right away or sit with your head lowered between your knees.

Follow-up care

Follow up with your doctor as instructed.

Call 911

Call 911 if any of the following occur:

  • Another fainting spell occurs, and it is not explained by the common causes listed above

  • Fainting or loss of consciousness

  • Chest, arm, neck, jaw, back, or abdominal pain

  • Shortness of breath

  • Weakness, tingling, or numbness in one side of the face, one arm or leg

  • Slurred speech, confusion, trouble walking or seeing

  • Seizure

  • Blood in vomit or stools (black or red color)

When to seek medical care

Get prompt medical attention if you have occasional mild lightheadedness, especially when standing up.


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