Fainting is a loss of consciousness that happens quickly and sometimes without warning. A fainting episode usually resolves within seconds to minutes. If fainting is caused by another condition, then the condition will need to be treated.


In general, fainting is caused by decreased blood flow to the brain.
Blood Flow to the Brain
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Decreased blood flow to the brain can be caused by:Most commonly, vasovagal spells. Vasovagal spells can occur:
  • During medical procedures
  • During times of high stress, trauma, or fright
  • After standing still for a long period of time
Medical conditions:Fainting can also occur as a side effect to medications. These include:
  • Blood pressure medications
  • Medications to regulate heart rhythms
  • Diuretics
  • Certain antidepressants

Risk Factors

Factors that increase your risk of fainting include having a history of fainting.


Symptoms may include:
  • Sudden loss of consciousness
  • Inability to remain standing or sitting
  • Consciousness regained without any need for intervention
  • Lightheadedness before losing consciousness

When Should I Call My Doctor?

Call your doctor if you are having episodes of fainting. This is especially important if you:
  • Have a heart condition
  • Have a job where you or others may be at risk if you faint. Examples include airline pilot, bus driver, or machinist.

When Should I Call for Medical Help Immediately?

Call for emergency medical services right away if you have:
  • Weakness or numbness of face, arm, or leg, especially on the left side of the body
  • Confusion
  • Loss of balance, coordination problems
  • Vision problems
  • Severe headache
  • Rapid, irregular heartbeat; chest pain

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