Fainting Symptoms, Causes & Common Questions

Understand your fainting symptoms with Buoy, including 9 causes and common questions concerning your fainting.

  1. 9 Possible Fainting Causes
  2. Real-Life Stories
  3. Fainting FAQ
  4. Questions Your Doctor May Ask
  5. Statistics
  6. Related Articles

9 Possible Fainting Causes

The list below shows results from the use of our quiz by Buoy users who experienced fainting. This list does not constitute medical advice and may not accurately represent what you have.

Orthostatic syncope (fainting)

Orthostatic syncope refers to a type of loss of consciousness caused by rapidly standing up from a sitting position, and not enough blood reaches the head. This can cause a person to pass out, but then come back to consciousness without lasting effects.

Rarity: Uncommon

Top Symptoms: lightheadedness, brief fainting episode, dizziness and lightheadedness before passing out, fainting after standing up, fainting for the first time

Symptoms that always occur with orthostatic syncope (fainting): brief fainting episode, fainting after standing up

Urgency: Phone call or in-person visit

Stroke or tia (transient ischemic attack)

Transient ischemic attack, or TIA, is sometimes called a "mini stroke" or a "warning stroke." Any stroke means that blood flow somewhere in the brain has been blocked by a clot.

Risk factors include smoking, obesity, and cardiovascular disease, though anyone can experience a TIA.

Symptoms are "transient," meaning they come and go within minutes because the clot dissolves or moves on its own. Stroke symptoms include weakness, numbness, and paralysis on one side of the face and/or body; slurred speech; abnormal vision; and sudden, severe headache.

A TIA does not cause permanent damage because it is over quickly. However, the patient must get treatment because a TIA is a warning that a more damaging stroke is likely to occur. Take the patient to the emergency room or call 9-1-1.

Diagnosis is made through patient history; physical examination; CT scan or MRI; and electrocardiogram.

Treatment includes anticoagulant medication to prevent further clots. Surgery to clear some of the arteries may also be recommended.

Rarity: Common

Top Symptoms: dizziness, leg numbness, arm numbness, new headache, stiff neck

Symptoms that never occur with stroke or tia (transient ischemic attack): bilateral weakness

Urgency: Emergency medical service

Vasovagal syncope

Vasovagal syncope is sudden fainting caused by a sudden drop in heart rate and blood pressure when your body overreacts to certain emotional or neurologic triggers. A loss of consciousness occurs due to reduced blood flow to the brain.

Those with vasovagal syncope will also experienc...

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Concussion not needing imaging

A traumatic brain injury (TBI), or concussion, happens when a bump, blow, jolt, or other head injury causes damage to the brain. Every year, millions of people in the U.S. suffer brain injuries. More than half are bad enough that people must go to the hospital, and the worst injuries can lead to permanent brain damage or death.

Rarity: Common

Top Symptoms: dizziness, irritability, depressed mood, difficulty concentrating, trouble sleeping

Symptoms that always occur with concussion not needing imaging: head or face injury

Symptoms that never occur with concussion not needing imaging: recent fall from 6 feet or higher, severe vomiting, posttraumatic amnesia over 30 minutes, slurred speech, fainting, moderate vomiting

Urgency: Primary care doctor

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Narrowing of the aortic valve

Narrowing of the aortic valve is also called aortic valve stenosis, aortic stenosis, or AS. The aortic valve controls the flow of blood from the heart into the aorta, the body's main artery. If the aortic valve is abnormally narrow, the blood being pushed through it is blocked. Pressure may build up within the heart, causing damage.

AS may be caused by a congenital malformation of the valve, or by calcium deposits and/or the scarring that occurs as a person ages.

Symptoms may not appear right away. There will be chest pain with the feeling of pounding heartbeat, as well as shortness of breath with fatigue, lightheadedness, or even fainting.

It is important to see a medical provider for these symptoms, since AS can lead to stroke, blood clots, and heart failure.

Diagnosis is made through physical examination, echocardiogram, CT scan, and sometimes a stress test.

Treatment may simply involve monitoring and medication, while making lifestyle improvements in diet, exercise, weight, and smoking. Surgery to repair or replace the faulty aortic valve may be recommended.

Rarity: Uncommon

Top Symptoms: fatigue, shortness of breath, chest pain, shortness of breath on exertion, decreased exercise tolerance

Urgency: Hospital emergency room

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) means "abnormal thickening of the heart muscle." This can interfere with the heart's ability to pump blood.

Most often, an inherited genetic mutation causes HCM. However, aging, high blood pressure, diabetes, or thyroid disease can sometimes bring it about.

Many people have no symptoms at all. Some have unexplained chest pain, shortness of breath, fainting, or the feeling of rapid, fluttering heartbeat, because the abnormally thick heart muscle interferes with normal heartbeat and causes an arrhythmia. Take the patient to the emergency room or call 9-1-1.

Untreated hypertrophic cardiomyopathy can lead to serious heart disease and even sudden cardiac arrest and death, especially in people under age 30.

Diagnosis is made through echocardiogram; electrocardiogram; treadmill stress test; and/or cardiac MRI.

Treatment involves medication to relax the enlarged heart muscle and slow the rapid pulse. Surgery to remove some of the thickened muscle may be done, or a defibrillator may be implanted.

Anyone with a family history of HCM should ask their medical provider about screening for the disease, which involves regular echocardiography.

Rarity: Rare

Top Symptoms: fatigue, shortness of breath, dizziness, racing heart beat, shortness of breath on exertion

Urgency: Primary care doctor


Dehydration means the body does not have enough water to carry out its normal processes.

Most susceptible to serious dehydration are young children with fever, vomiting, and diarrhea. In adults, some medications increase urination and can lead to dehydration. Anyone exercising vigorously, especially in hot weather, can quickly become dehydrated.

Symptoms include extreme thirst; dry mouth; infrequent, dark-colored urine; dizziness; and confusion. Young children may have sunken eyes, cheeks, and soft spot on top of the skull.

Severe dehydration is a serious medical emergency that can lead to heat stroke, kidney damage, seizures, coma, and death. Take the patient to the emergency room or call 9-1-1.

Diagnosis is made through blood tests and urine tests.

Mild dehydration can be treated simply by drinking extra water, or water with electrolytes such as sports drinks. More serious cases may be hospitalized for intravenous fluids.

It's important for anyone who is outside in hot weather, or who is ill, to drink extra fluids even before feeling thirsty as thirst is not always a reliable guide.

Rarity: Rare

Top Symptoms: fatigue, dizziness, vomiting or diarrhea, racing heart beat, being severely ill

Urgency: Hospital emergency room

Heart attack

Most heart attacks happen when a clot in the coronary artery blocks the supply of blood and oxygen to the heart. Often this leads to an irregular heartbeat - called an arrhythmia - that causes a severe decrease in the pumping function of the heart.

Rarity: Uncommon

Top Symptoms: chest pain, shortness of breath, tight, heavy, squeezing chest pain, being severely ill, nausea

Urgency: Emergency medical service

Long qt syndrome

Long QT syndrome is an inherited or acquired condition of the heart that results in abnormal heart rhythms (arrhythmias). The heart beats dangerously fast and erratically due to dysfunction in the electrical activity of the heart.

Symptoms include fainting and therefore a higher risk of ...

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Real-life Stories

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FAQs About Fainting

Here are some frequently asked questions about fainting.

How do you feel when you are about to faint?

Fainting or syncope refers to a rapid onset loss of consciousness that is short in duration, typically caused by a decrease in blood flow to the brain. Before you lose consciousness, you may experience symptoms such as lightheadedness, sweating, and nausea.

Why do I faint after I get up in the morning?

When you sit or stand up in the morning, your brain is elevated above your heart, and thus it requires a higher pressure to supply blood to your brain. Your body accomplishes this by constricting your vessels throughout your body to maintain blood pressure. You may experience an initial decrease in blood pressure upon sitting or standing up which may cause you to faint. This is particularly true if you are dehydrated and get up quickly. Thus, fainting occurs more frequently in the mornings when you may have just spent eight hours without any fluid intake.

Why does the sight of blood make me faint?

When you are in the presence of a stressor such as the sight of blood, it may trigger your nervous system to slow down and your heart to dilate your blood vessels both of which contribute to decreasing your blood pressure. This is also known as the vasovagal reflex. If your blood pressure becomes sufficiently low, you will not be able to maintain perfusion of your brain and you will faint. In some people, this fainting response can also result from situational triggers such as urination or coughing.

Can you faint from not eating?

Yes, if you do not eat for an extended period of time, your blood sugar will decrease (hypoglycemia). If it becomes sufficiently low, your brain will no longer have enough energy to maintain consciousness. If you are not eating due to nausea, you may also be drinking less fluids and become dehydrated which predisposes you to fainting.

How do you stop yourself from fainting?

There's a number of ways to decrease your fainting episodes depending on the underlying cause. Always keep yourself well hydrated. If you feel lightheaded, consider lying down and elevating your legs such that they are above the level of your head. If you faint in response to specific triggers such as the sight of blood, avoid those triggers if possible.

Questions Your Doctor May Ask About Fainting

To diagnose this condition, your doctor would likely ask the following questions:

  • How long were you unconscious?
  • Do you notice your heart beating hard, rapidly, or irregularly (also called palpitations)?
  • Have you been experiencing dizziness?
  • Were you confused and disoriented when you woke up?

If you've answered yes to one or more of these questions

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Fainting Symptom Checker Statistics

People who have experienced fainting have also experienced:

  • 6% Dizziness
  • 6% Fatigue
  • 6% Nausea

People who have experienced fainting were most often matched with:

  • 63% Stroke Or Tia (Transient Ischemic Attack)
  • 18% Orthostatic Syncope (Fainting)
  • 18% Vasovagal Syncope

Source: Aggregated and anonymized results from Buoy Assistant (a.k.a. the quiz).

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