Fainting: Symptoms, Causes & Preventative Measures

Fainting, or syncope, is something most people experience at least once in their lives. While it’s often harmless, it can sometimes signify a more serious issue. In this article, we’ll explore what causes fainting, how to recognize it, and when to seek medical help. Let’s discover what you need to know about this common but mysterious condition.

What is Fainting (Syncope)?  

Fainting, also called syncope (sin-copay), is a brief loss of consciousness (passing out) that lasts for a few seconds to a few minutes before you regain consciousness. Some causes of fainting are harmless, such as dehydration or not eating. In contrast, others can be life-threatening, such as atrial fibrillation, which is a type of irregular heartbeat.

Common Causes of Fainting  

What Causes Fainting?  

Fainting or syncope occurs when there is a sudden decrease in blood flow to the brain. The brain does not get enough oxygen, causing a temporary loss of consciousness.

Cardiac Syncope

The heart muscle pumps blood to the rest of the body. Cardiac syncope occurs due to a problem with the heart, which affects its ability to pump enough blood to the brain.

Carotid Sinus Syncope

The carotid arteries are blood vessels in the neck that supply blood to the brain. A carotid sinus syncope can occur if something pinches or presses upon these blood vessels. For example, direct pressure on the neck, wearing tight clothing, overstretching the neck, or overgrowth of a bone that presses upon the carotid artery.

Vasovagal Syncope

Vasovagal syncope is a neurally mediated syncope triggered by a stressful event. It occurs when the nervous system overreacts and blood pressure drops. This prevents the brain from getting oxygenated blood for a few minutes, leading to syncope or fainting. The sudden drop in blood pressure and heart rate is a type of reflex syncope that happens automatically and is not controlled.

Potential triggers that can cause vasovagal syncope include:

• Fatigue or exhaustion

• Physical trauma

• Severe pain

• Emotional trauma or emotional distress

• Sight of blood or needles

• Movements during peeing, pooping, straining, coughing, or stretching

Dehydration and Overheating

Dehydration (lack of enough fluids), excessive sweating, and overheating can lead to fainting spells. This occurs due to a reduction in the circulating blood volume, making it harder for your heart to deliver oxygen-rich blood to vital organs such as the brain.

Low Blood Pressure (Orthostatic Hypotension)

Orthostatic hypotension is a type of postural low blood pressure that occurs when one moves too quickly from sitting or lying to standing. The sudden drop in blood pressure can lead to dizziness, lightheadedness, and fainting. It is called a head rush or pre-syncope if one feels faint but doesn’t lose consciousness. This type of fainting is particularly common in the elderly and is a frequent cause of falls.

Low Blood Sugar (Hypoglycemia)

People with diabetes who take insulin and other diabetes medications can develop hypoglycemia (low blood sugar). Rarely, hypoglycemia can cause fainting or brief loss of consciousness.

Other Health Conditions

Other causes of fainting may include an underlying health condition such as:

• Anemia

• Seizure disorders

• Head injury

• Heart attack

• Stroke

Medications

Certain medications can cause fainting as a side effect. For example, medications used to treat hypertension (high blood pressure) can cause fainting by causing a drop in blood pressure. Older adults may be more sensitive to medications and at a higher risk of fainting and falls. 

Examples of medicines that can make you lose consciousness briefly include:

• Diuretics (water pills) 

• Angiotensin-converting enzyme (ACE) inhibitors 

• Calcium channel blockers 

• Nitrates used to treat heart disease 

• Antihistamines

• Opioid pain medications

• Antipsychotics

Lifestyle Factors

Certain lifestyle factors can lead to fainting, such as:

• Skipping meals

• Not drinking enough water

• Physical exhaustion (working or playing hard, especially in hot weather)

• Hyperventilating (breathing fast)

• Standing up quickly 

• Using alcohol, marijuana, or illegal drugs

What Is The Most Common Cause of Syncope?

The most common cause of syncope or fainting is a sudden drop in blood pressure, which decreases blood flow and oxygen supply to the brain. 

Common Symptoms of Impending Syncope  

Warning Signs You’re About to Pass Out

Presyncope is a feeling that you are about to faint. Warning signs that you are about to lose consciousness may include:

• Dizziness

• Lightheadedness

• Cold and clammy skin

• Hot and sweaty skin

• Weakness

• Heart palpitations

• Emotional stress, anxiety, or restlessness

What Happens After a Syncope Episode?

After a syncope episode, you may experience:

• A fall

• Headache

• Confusion

• Loss of muscle control

• Chest pain

• Shortness of breath

• Changes in vision such as blurry vision, seeing stars, gray-out, blackout, whiteout, or tunnel vision

• Ringing in the ears

• Numbness and tingling

• Nausea, vomiting, stomach pain

• Loss of bladder or bowel control

Simple Fainting vs Cardiac Syncope 

People who experience “simple fainting” often have presyncope or a feeling that they are about to faint with symptoms such as lightheadedness, dizziness, nausea, graying out of vision, palpitations, weakness, or sweating. 

In contrast, cardiac syncope often occurs without warning or presyncope symptoms such as dizziness. It is typically caused by arrhythmias, structural heart disease, or other cardiovascular conditions and requires urgent medical evaluation.

What Can Be Mistaken For Fainting?  

As mentioned, fainting occurs when there isn’t enough blood flow to the brain. It’s a common symptom, and about 50% of people experience fainting at least once in their lifetime.

Seizures occur when the electrical activity in the brain is disturbed. They are less common, and about 10% of people experience one in their lifetime. Different types of seizures can cause various symptoms, such as loss of consciousness, staring into space, or shaking violently.

Responding to Fainting Episodes  

What To Do If I Feel Faint?

If you feel like you are going to faint, lie down and keep your legs raised. This increases blood flow to your brain with gravity. If you can't get into a lying position, sit with your head between your knees.

How Do You Respond to a Person With Syncope?

If someone faints:

• Make sure the person’s airway is not blocked.

• Check if they are breathing.

• Check if they have a pulse.

• Call 911 or seek medical attention immediately if they have any injuries.

• Begin CPR (cardiopulmonary resuscitation) if the person isn’t breathing and does not have a pulse. Check out how to do CPR.

• Look for an automated external defibrillator (AED). This device can restart the heart in people experiencing cardiac arrest.

What To Do After a Person Regains Consciousness?

After a person wakes up after fainting:

• Check for any injuries.

• Ensure fresh air.

• Have the person lie down or sit leaning forward with their head between their knees for 10-15 minutes.

• Offer cold water. 

When to Seek Medical Assistance  

Most fainting episodes are due to harmless causes and are not a medical emergency. However, you should seek a medical evaluation if you have frequent fainting spells or other symptoms. 

Seek medical care if you have the following symptoms with fainting: Chest discomfort or pain, shortness of breath, vision changes, confusion, slurred speech, irregular heartbeat, or loss of bladder control.

Also, seek medical care if you have fainting episodes while exercising, injuries from a fall sustained during fainting, or if you take more than a few minutes to regain consciousness. 

People who are pregnant, have diabetes or heart problems, or have a family history of sudden death should have a fainting episode evaluated by a healthcare professional.

Diagnostic Tests for Fainting

Your doctor can do a diagnostic workup to find out if you have an underlying medical condition, such as a heart arrhythmia or seizure disorder causing your fainting spells.

Some of the tests your healthcare provider may do include blood tests, electrocardiogram (EKG), echocardiogram, tilt table test, Holter monitor, and electroencephalogram (EEG).

How is Fainting Treated?

A single episode of fainting does not usually require treatment. Treatment for fainting depends on the underlying cause. For example:

If fainting is due to orthostatic hypotension (a drop in blood pressure with changes in position), your doctor may change your medications, recommend compression stockings, encourage fluid and salt intake, and/or prescribe leg exercises.

Long-Term Care  

If you are diagnosed with a heart condition, treatment options may include medications, catheter ablation, pacemaker placement, implantable cardioverter defibrillator (ICD), or heart valve replacement surgery.

Carotid sinus syncope may be treated with medication or a pacemaker. 

Prevention and Management of Fainting  

Lifestyle Strategies to Prevent Fainting  

Some fainting episodes are reflex syncope and are not in your control. However, you can prevent fainting caused by specific activities or lifestyle factors:

• Drink plenty of water and stay well hydrated. 

• Stand up slowly when getting out of bed.

• Avoid activities that trigger vasovagal syncope.

If you feel faint, try the following:

• Lie down.

• Sit with your head between your knees.

• Try counter-pressure measures to increase blood pressure, such as:

  • Make a fist with your hand.

  • Interlock your fists.

  • Tense your arm muscles.

  • Pull your arms apart.

  • Squeeze your leg muscles.

  • Press your thighs together.

  • Cross your legs.