Fainting (Syncope)

Fainting is a temporary loss of consciousness. Though temporary, fainting can signal a more serious condition. You may injure yourself when you lose consciousness. Vasovagal syncope is a common cause of fainting. It occurs when your body overreacts to specific triggers, for example, the sight of blood or extreme emotional distress.

What causes fainting?

Fainting usually occurs when the heart isn’t able to pump a normal amount of oxygen-rich blood to the brain. This can be caused by many things, including:

  • Pain
  • Overheating
  • Dehydration
  • Emotional distress
  • Exhaustion
  • Some medicines
  • Rapid changes in blood pressure or body position
  • Underlying medical conditions

Symptoms of fainting

The primary symptom of fainting is a temporary loss of consciousness. People who experience fainting may also experience the following symptoms:

  • Skin paleness
  • Feeling lightheaded or dizzy
  • Nausea
  • Cold clammy sweat
  • Feeling drowsy or groggy
  • Changes in vision, such as tunnel or blurred vision
  • Headaches

How is fainting diagnosed?

Fainting can be a symptom of serious underlying heart, metabolic, neurologic and lung conditions. To help rule out underlying heart issues, your doctor will give you a physical exam and may recommend one or more of the following tests to rule out more serious causes of fainting:

How is fainting treated?

Treatment for fainting will vary depending on what is causing it. You may need to make adjustments to your lifestyle, including changes to medications or diet and avoiding things that trigger fainting.

Common triggers for vasovagal syncope include:

  • Standing in one place for long periods of time
  • Heat exposure
  • Straining, such as what occurs when having a bowel movement

If your doctor finds that an underlying condition such as arrhythmia (abnormal beating of the heart) is causing your fainting, you may need to consult with an electrophysiologist to determine if you need an implanted pacemaker or a cardiac defibrillator.