Fainting: Vagal Reaction

Fainting (syncope) is a temporary loss of consciousness that is associated with a loss of postural tone. It’s also called passing out. It occurs when blood flow to the brain is less than normal. Your healthcare provider believes that your fainting was because of a vagal reaction. This condition is not a sign of serious disease.

A vagal reaction is a response in your body that causes your pulse to slow down or the blood vessels to expand. This causes your blood pressure to fall. And this sends less blood to your brain if you are standing or sitting. That results in dizziness, near-fainting, or fainting. Lying down usually stops the reaction within 60 seconds.

This response can occur during sudden fear, severe pain, emotional stress, overexertion, overheating, hunger, nausea or vomiting, prolonged standing, or standing up after sitting or lying for a long time.

Home care

Follow these guidelines when caring for yourself at home:

  • Rest today. Go back to your normal activities as soon as you are feeling back to normal.

  • Stay hydrated and avoid skipping meals.

  • If you feel lightheaded or dizzy, lie down right away. Or sit with your head lowered between your knees.

Follow-up care

Follow up with your healthcare provider, or as advised.

When to seek medical advice

Call your healthcare provider right away if any of these occur:

  • Another fainting spell that’s not explained by the common causes listed above

  • Pain in your chest, arm, neck, jaw, back, or abdomen

  • Shortness of breath

  • Severe headache or seizure

  • Your heart beats very rapidly, very slowly, or irregularly (palpitations)

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