Fainting: Causes, Types, And Prevention

Have you ever felt a sudden drop in your blood pressure as if you’re just about to collapse? 

With a drop in blood pressure or heart rate, some individuals can experience a loss of muscle control and consciousness. 

This happens when blood vessels that ensure a constant blood pressure expand or dilate, resulting in oxygen deprivation to the brain, which causes loss of consciousness (fainting) due to low blood pressure. 

This article discusses everything about fainting, what causes it, its types, and how to prevent it. 


What Is Fainting?

Fainting, a medical term for syncope or syncopal episode, is a sudden, temporary loss of consciousness accompanied by the loss of muscle tone. This often occurs when there’s a temporary drop in blood pressure, due to which the heart doesn’t pump enough blood to the brain. 

In most cases, fainting usually lasts from a few seconds to a few minutes. The person then regains consciousness when the blood flow returns to normal. 

Usually, syncope is not a cause for concern. But sometimes, it can be a sign of an underlying medical condition if you faint more often accompanied by other symptoms. 

Fainting can occur at any age and affect healthy people, but it is more frequent in people as they get older. You should always seek medical attention if a person doesn’t regain consciousness within a few minutes. 

Presyncope: Presyncope is a feeling of nausea or lightheadedness, which indicates that you’re about to faint. Someone with a presyncope feels sweaty, weak, has palpitations, and has trouble hearing or visual “gray out.”

How Common Is Fainting?

Syncope is a common medical problem having a frequency ranging from 15% to 39%. People with or without any medical condition can experience this condition at any age. About 3.5% of women and 3% of men experience fainting at some point in their lives. About 6% of people experience fainting more often (11.1 episodes per 1000 individuals) as they get older. 

Types of Fainting

Some common types of syncope include:

1. Vasovagal Syncope

It is one of the most common types of syncope and the main reason for emergency department visits. During vasovagal syncope, the disruption of the balance between acetylcholine and adrenaline occurs. 

Adrenaline makes blood vessels narrower and heartbeat faster and increases blood pressure, while acetylcholine does the opposite. The stimulation of the vagus nerve causes the release of excess acetylcholine. 

As a result, heart rate slows, and blood vessels expand, decreasing the blood flow to the brain and causing loss of consciousness. 

Vasovagal syncope occurs as a result of stressful events, including: 

  • Pain

  • Emotional trauma and stress

  • Standing for a long time

  • Standing up quickly, which can cause a “head rush.”

  • The sight of the blood

Vasovagal syncope, also called cardio-neurogenic syncope, usually occurs because of an upright posture and results in lightheadedness, a sensation of warmth, and tunnel vision (visual gray-out). 

2. Cardiac Syncope

Cardiac syncope involves fainting episodes because of various heart complications like hypotension, tachycardia, bradycardia, increasing the risk of sudden cardiac death. It also occurs due to a reduced supply of oxygenated blood pumped to the brain because of potential heart conditions. 

In older adults aged over 70, recurrent syncope can occur due to atrial fibrillation or heart failure. 

3. Situational Syncope

Situational syncope is a common type of vasovagal syncope that occurs due to specific situations that affect the nervous system, leading to fainting spells. 

Some common situations include:

  • Sudden abdominal pain

  • Eating a meal (swallowing)

  • Coughing, sneezing, laughing

  • Intense emotional stress

  • Defecating

  • Pressure on the chest after exercise

  • Hyperventilation 

  • Dehydration

  • Use of alcohol or drugs

  • Urinating (occurs in men while standing to urinate – micturition syncope). 

4. Carotid Sinus Syncope

This type of syncope happens in older adults due to constriction of the carotid artery in the neck. The carotid artery is a blood vessel in the neck responsible for supplying blood to the brain. The carotid artery is pinched when you wear a collar that is too tight or turn your head to one side. 

5. Postural Syncope

The type of syncope that occurs when you quickly change your posture, such as from lying down to standing, is called postural syncope. A sudden change in posture also causes a temporary drop in blood pressure. 

Dehydration and certain medications can cause syncopal episodes. People who experience postural syncope experience a reduction in their blood pressure by at least 20 mmHg/ 10 mmHg while standing up. 

Symptoms of Syncope

One of the primary symptoms of syncope is losing consciousness. Other most common warning signs and symptoms include:

  • Sweating

  • Nausea

  • Lightheadedness

  • Blurred or “tunnel” vision

  • Headaches

  • Slurred speech

  • Rapid heartbeat

  • Feeling as if sounds are fading away

  • Sudden changes in body temperature, such as chills or flushes

  • Confusion 

A person having syncopal episodes also experiences:

  • Falling down

  • Loss of muscle control

  • Unusual paleness of the skin

  • A weak pulse

  • Blacking out

  • Hearing ringing in the ears

Sometimes, syncope may also occur due to a more serious event like a disturbance in the regular heart rate or a stroke. Frequent fainting can also be a symptom of something serious that might be telling you to need further examination. 

If you experience heart palpitations, faster or slower pulse, chest pains, or breathlessness, you should see a doctor. 

What Are the Causes of Fainting?

Occasionally, fainting occurs without any cause, and the person returns to consciousness after a few minutes. Sometimes, fainting results from environmental triggers, and sometimes, it occurs due to an emotional response to trauma. 

Changes in blood volume, low blood sugar, and intense pain can also cause fainting episodes. Some common causes of syncope include:

1. Dehydration

A drop in the body’s fluids causes a reduction in blood pressure. Dehydration causes blood volume to drop, making it hard for your body to stabilize blood pressure. 

As you age, your thirst mechanism and kidneys don’t work well, and you don’t think you’re becoming dehydrated. This may lead to fainting. 

2. Some Neurological Conditions

Brain disorders or neurological conditions like Parkinson’s disease narrow the blood vessels in the brain that lead to syncopal episodes. 

3. Uncontrolled Diabetes

Frequent urination is a symptom of diabetes that leads to dehydration. Diabetes also causes damage to certain nerves that regulate blood pressure.

4. Alcohol Consumption

Excessive alcohol consumption (alcohol abuse) in a short amount of time causes people to faint. 

5. Some Medications

The use of different medications for different conditions (polypharmacy) can lead to syncope due to adverse reactions and drug interactions. 

Medications also increase your chances of fainting by causing a drop in blood pressure. Some medications that cause fainting include beta-blockers, diuretics, antihypertensive drugs, and antidepressants. 

6. Orthostatic Hypotension

This condition is characterized by a sudden drop in blood pressure when you stand up suddenly, resulting in lightheadedness and fainting. 

If orthostatic hypotension leads to frequent syncopal episodes, it means that your body is trying hard to maintain healthy blood pressure.

7. Pregnancy

Pregnancy can also cause fainting because of orthostatic hypotension and compression of the inferior vena cava by the expanding uterus. 

Other medical conditions that may cause syncope are:

  • Seizures

  • Anxiety

  • Atherosclerosis

  • Chronic lung disease, such as emphysema

  • Arrhythmia 

When Is Fainting an Emergency?

You should call 911 or another relevant emergency service if someone faints and:

  • Has difficulty with speech or vision

  • Pregnant

  • Doesn’t regain consciousness within a few minutes

  • Unable to move their muscles

  • Has an irregular heartbeat

  • An older adult with no history of fainting

  • Not breathing

  • Has lost bladder control

  • Has convulsions

  • Disoriented and confused

  • Has fallen and sustained an injury

How Is Syncope Diagnosed?

Ruling out the cause of syncope is crucial as it can help you identify the underlying medical conditions on time. 

Some tests can help you determine the cause of syncope. They can also check blood flow, blood volume, the amount of blood in your body, and how fast your heart is beating. These tests include:

1. Tilt Table Test: This test is performed to measure and record your blood pressure and heart rate in response to different positions, including sitting, standing, lying down, and upright tilt. 

2. Physical Examination: Physical examination includes carotid sinus stimulation and vital orthostatic signs.

3. Electrocardiogram (ECG/EKG): ECG records the electrical rhythm of your heart by creating a graph. During ECG, electrodes are taped to different parts of your body to collect the information. 

4. Exercise Stress Test: This test records ECG while you’re strenuously exercising. 

5. Ambulatory Monitor: The information about your heart rate and rhythm is recorded by wearing a monitor that uses electrodes.

6. Echocardiogram: This test is performed to get an ultrasound of the heart for creating an image of heart structures. An echocardiogram uses very high-frequency sound waves. 

Portable Diagnostic Monitors

1. Event Monitor: This is a portable ECG device that you have to wear under your clothing for one to two months. Event monitor activates and records only when you have an abnormal heart rate. 

2. Holter Monitor: Holter monitor is an in-home portable device that you have to wear for 1-7 days to record and display heart rhythms. An individual has to press the button of the device whenever it feels they’re about to faint. 


If the cause of fainting is not an underlying health condition, then there’s no need for treatment as fainting resolves within a few minutes. But if you experience syncope because of a medical condition, treatment is necessary. 

The following are some treatment options depending on the underlying condition:

1. Pacemakers: Pacemakers are devices used to treat heart failure, heart block, or bradycardia by providing electrical pulses through electrodes to the heart. Pacemakers are inserted below the collarbone. 

2. Implantable Cardioverter Defibrillators (ICDs): ICDs are used to deliver electrical pulses to the heart to regulate irregular heartbeat. These implanted devices are used to treat heart failure or ventricular tachycardia

3. Catheter Ablation: This treatment involves cauterizing those heart cells that cause dangerously abnormal heart rhythms. 

How to Prevent Fainting

If you experience fainting due to some trigger, such as extreme heat, then it is vital to avoid that trigger. In case of blood pooling in your legs and feet, exercising and wearing compression is important. 

Also, make sure you drink plenty of fluids following a syncopal episode. Always try not to skip meals. Standing up suddenly can cause a head rush; make sure you get up slowly from a lying down or sitting position. 

If you notice any of the symptoms of fainting, you should immediately sit and place your head between your knees so that the blood supply to your brain can get back to normal. 

What To Do If Someone Faints

You should do the following if you notice someone fainting:

  • Loosen tight clothing and help them get some fresh air.

  • Lie them down on their back.

  • If the person regains consciousness, help them to get up slowly. 

If a person doesn’t regain consciousness, follow DRSABCD:

  • Danger: Make sure you’re not putting yourself in danger while helping the person.

  • Response: Check out if the patient responds to you by squeezing their shoulder, talking to them, or asking their name.

  • Send for help: If the patient doesn’t respond, call the emergency service. 

  • Airway: Check out if the patient is breathing and their airways are clear. If not, perform a head chin-tilt lift.

  • Breathing: Notice if the patient is breathing or not. 

  • CPR: If the patient is not breathing, start CPR by laying them on their back. Continue until the patient recovers. 

  • Defibrillator: Apply an Automated External Defibrillator if the patient is unconscious. The device will give electrical shocks to the patient to re-establish the normal heartbeat. 


Proper diagnosis and management are very helpful in controlling syncopal episodes. There are many causes of fainting that come with no medical concern. But if fainting is the result of an underlying medical condition, it should be managed appropriately.


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