Fainting (syncope)

What is fainting?

Fainting, also known as syncope, is a sudden, temporary loss of consciousness caused by a decrease in blood flow to your brain. It can happen when your blood pressure or heart rate suddenly drops.

Passing out unexpectedly can be scary. Usually, it’s not a major cause for concern and most people fully recover quickly. However, fainting can be dangerous if a person falls and hits their head or injures themselves in another way.

There are several types of syncope, including:

  • Vasovagal syncope: The most common type of syncope, which is usually harmless and occurs in response to triggers, like fear, standing too long or seeing blood
  • Situational syncope: A type of vasovagal syncope caused by certain activities that strain the heart’s ability to pump blood, such as coughing, using the bathroom or swallowing
  • Cardiac syncope: Results from an underlying heart or blood vessel condition that affects the blood flow to your brain
  • Neurologic syncope: Involves neurological conditions like seizures or stroke
  • Postural or orthostatic syncope: Occurs when you stand up or lie down too quickly, which causes your blood pressure to drop
  • Postural Orthostatic Tachycardia Syndrome (POTS): Due to a very rapid heartbeat that happens when you stand up or sit down
  • Unknown causes

Syncope can also be a sign of a more serious underlying condition. If you experience a fainting episode, it’s important to talk to your doctor to rule out any health issues.

Symptoms of fainting

You may experience one or more of these common symptoms before fainting:

  • Feeling dizzy or lightheaded
  • Feeling groggy
  • Feeling warm or flushed
  • Blurred or darkened vision
  • Nausea
  • Sweaty palms
  • Heart palpitations
  • Headache

Causes of fainting

Not getting enough blood flow to your brain causes you to pass out. There are many reasons why this can occur:

Response to certain triggers:

  • Having low blood sugar
  • Dehydration
  • Overheating
  • Standing up quickly
  • Sudden emotional distress or pain
  • Certain medications
  • The sight of blood
  • Coughing, laughing or sneezing

Underlying cardiovascular conditions:

Who is at risk for fainting?

Anyone can pass out, but certain risk factors can increase your chance of doing so:

  • Underlying heart conditions: People who have existing cardiac conditions are more likely to have an episode of syncope
  • Previous syncope: If you’ve fainted before, you’re more likely to pass out again
  • Age: The risk of developing a heart condition, becoming less active, having decreased blood circulation and taking medication that causes fainting increases as you get older
  • Certain health conditions: People with kidney failure, POTS, epilepsy, diabetes or Parkinson’s disease are more likely to develop syncope issues
  • Other risk factors: The risk of having a syncope diagnosis increases with:
    • Taking certain medications
    • Being dehydrated
    • Heat exposure
    • Blood loss

Fainting treatment options

If you see someone faint, make sure their airway is clear, check their breathing and have them lie down for at least 10 minutes. If they don’t improve, call 911.

At Main Line Health, our specialists will work with you to determine the cause of your syncope and whether additional treatment is needed. Treatment for fainting may include:

  • Lifestyle changes, such as staying hydrated or changing your diet
  • Avoiding known triggers that can cause you to pass out, like changing positions quickly and prolonged standing
  • Medications
  • Cardiac ablation
  • Heart surgery, like getting a pacemaker or an implantable cardioverter-defibrillator (ICD)

Diagnosis and testing for fainting

In order to diagnose syncope, your doctor will conduct an evaluation through tests that may include:

  • Exam: You'll discuss your symptoms and medical history with your doctor to rule out any heart, neurological or other health conditions
  • Diagnostic tests: Your doctor may order various tests, such as an electrocardiogram (ECG or EKG), echocardiogram or stress test
  • At-home cardiac monitoring: You may be asked to wear a holter monitor or event monitor
  • Bloodwork: Your doctor may order blood tests to look for certain indicators of conditions like anemia or low blood sugar that might have caused you to faint


Emergency Medicine

Take comfort in knowing that the Emergency Care Team at Main Line Health is here for you when you need us most to provide compassionate care as quickly as possible.

Genetics and Risk Assessment

Genetic evaluation is becoming an important part of personalized care, as many health conditions have a genetic basis and genetic test results can help to guide medical decisions. Our genetic counselors provide consultations related to cancer genetics, cardiovascular genetics and prenatal genetics.