Fainting (syncope) is a sudden and brief loss of consciousness. In some cases, the person both faints and falls to the ground (“passes out”). There are several potential causes of fainting, but the most common is a brief drop in the blood supply to the brain. People with mental disorders such as specific phobias, eating disorders, panic disorder and others may sometimes experience fainting as a symptom. In addition, patients who use certain medications (including antipsychotics and antidepressants) to treat emotional disorders may experience fainting as a side effect.
Just before a person faints, the skin may appear pale and their muscle tone may relax. The person may feel weak or nauseated, and have a sensation that surrounding noises are fading into the background. After fainting, a person usually regains consciousness within a couple of minutes and quickly makes a complete recovery.
In many cases, fainting is a medically harmless condition that should not worry the patient. However, in other cases fainting may be caused by a serious underlying medical condition. For this reason, all episodes of fainting should be viewed as potentially serious until a physician has had a chance to examine the patient and diagnose the cause of these episodes.
A physician may use several tests to help determine the cause of a patient’s fainting. During a tilt-table test, the patient lies flat on a table which is slowly tilted (head side up, feet side down) while blood pressure and heart rate are monitored. This can provide important information about how the gravitational stress (the force of gravity which causes the blood volume to move towards the feet when tilted) on the body’s autonomic nervous system (ANS) may trigger fainting. Tests that record the function of the heart and brain can also provide insight into the causes of fainting. However, in some cases the cause of fainting cannot be identified.
Fainting occurs when a person suddenly loses consciousness, most often due to a momentary drop in the supply of the blood to the brain. Also known as syncope, it is usually a brief episode that lasts just a couple of minutes and is followed by a rapid, complete recovery.
Mental disorders such as specific phobias, eating disorders, panic disorder and other conditions can sometimes cause a patient to faint. In addition, patients who use certain medications (including antipsychotics and antidepressants) to treat emotional disorders may experience fainting as a side effect of those medications.
During an episode of fainting, the autonomic nervous system (ANS) first creates an exaggerated response by increasing heart rate (rapid beats) and decreasing peripheral circulation (pale color) in an attempt to keep the blood flow stable. Following this initial exaggerated response, the blood pressure drops rapidly, reducing the blood flow to the brain. This inadequate blood flow causes the person to lose consciousness, and often, they will fall to the ground.
Once the person is lying flat, the blood flow to the brain quickly increases because it no longer has to fight gravity. For this reason, the person usually quickly regains consciousness. The patient may still feel tired for anywhere from a few minutes to a few hours before recovering.
In many cases, fainting may not be medically significant and should not worry the patient. However, in other cases, fainting may be caused by a serious underlying medical condition, such as heart rhythm disturbance (arrhythmia) or seizure disorder (e.g., epilepsy). Therefore, any episode of fainting should be considered potentially serious until a medical professional has determined otherwise and the cause is identified. This is particularly true of people who have heart-related problems, high blood pressure or diabetes.
Other symptoms related to fainting
Just before a person faints, their skin tone may turn pale and their muscle tone may relax. It is also not unusual for a person to feel weak or nauseated, and to have a sensation that surrounding noises are fading into the background.
Other signs and symptoms that may occur just before fainting include:
- Difficulty hearing
- Feeling of warmth
- Black out or white out in field of vision
- Lightheadedness or dizziness
- Rapid breathing (hyperventilation)
- Rapid heartbeats
A person who faints and exhibits slurred speech or difficulty moving an arm or leg afterward may have suffered a stroke (temporary or permanent loss of blood supply to the various brain areas). This requires immediate medical attention.
Patients should also notify a physician if fainting occurs suddenly without any warning signs, when turning one’s head or more than once in a one month period, or is associated with any of the following symptoms:
- Blurred vision
- Chest pain
- Irregular heartbeat
- Shortness of breath
- Difficulty talking
Potential causes and diagnosis of fainting
There are many different potential causes of fainting. A sudden decrease in blood flow to the brain is the most common cause, because it momentarily deprives the brain of an adequate flow of oxygen. Bleeding, severe dehydration or merely rising too quickly from a lying to a standing position can cause a drop in blood pressure that results in fainting. Actions that reduce oxygen flow to the brain can also lead to fainting, including standing for long periods of time, dehydration, coughing, urination and straining to have a bowel movement. Other causes of fainting include fear, emotional distress and hyperventilation (all symptoms potentially associated with mental disorders such as panic attacks and specific phobias), and severe pain.
Some people faint when their head is turned to the side. This may indicate that bones in the neck are pinching one of the blood vessels leading to the brain. A drop in blood sugar can cause fainting in both people with diabetes and in people who have not eaten for a long period of time (such as those with certain eating disorders). Use of both prescription drugs (including antipsychotics and antidepressants) and recreational drugs such as alcohol, marijuana and cocaine can cause fainting.
More serious causes of fainting include seizures and heart problems (e.g., arrhythmias, or irregular heartbeats, which may result from a number of conditions, including alcoholism [alcoholic cardiomyopathy]) or abnormalities in the blood vessels leading to the brain.
Several tests may be performed to reveal the cause of fainting including:
- Electrocardiograph (ECG). Machine that records the electrical impulses of the heart.
- Holter monitor. Machine that creates a record of the heart rhythm over 24 hours.
- Chest x-ray. A form of electromagnetic radiation that creates an image of the chest, lungs, heart, large arteries, ribs and diaphragm.
- Echocardiograph. Machine that creates an ultrasound image (produced by sound waves) of the heart.
- Electroencephalograph (EEG). Machine that creates a graphic record of brainwaves.
- Blood analysis. In some cases anemia (low red blood cell count) may make people feel lightheaded, or may cause fainting.
After ruling out the possible major physiological causes of fainting, a tilt-table test can also be performed to help determine neurological causes of a patient’s fainting. During this test, the patient lies flat on a table while blood pressure and heart rate are monitored. The table is tilted so the upper part of the body is raised in a fashion similar to going from a lying position to a standing position. The change in angle places stress on the autonomic nervous system (ANS), which regulates heart rate and blood pressure. The physician monitors the body’s reaction to this change, which can reveal important information about potential causes of fainting.
It should be noted that in some cases, the cause of fainting cannot be determined.
Relief options for fainting
Patients who feel faint should lie down immediately if possible. If lying down is not possible, they should sit down with their head between their knees, which will help force blood back to the brain.
If a person observes someone else fainting, several steps should be taken to aid the patient. These include:
- Place the patient so they are lying on the back. Legs should be elevated above the level of the heart.
- Watch the airway carefully. People who lose consciousness may vomit.
- Check breathing. Position an ear over the patient’s mouth and listen for breathing sounds. If breathing cannot be heard, dial 911 immediately and then initiate cardiopulmonary resuscitation (CPR, a technique designed to temporarily circulate oxygenated blood by chest compression and assisted breathing).
- Help restore blood flow. If the person is still breathing, elevate the legs above the level of the head. Loosen belts, collars and other clothing that may constrict breathing. If the person does not revive within two minutes, dial 911.
- Provide other aid as needed. Attend to any bumps, bruises or cuts suffered in a fall associated with fainting.
In some cases, fainting requires an emergency medical response. Call 911 if the patient fell from a height, does not regain consciousness quickly, is pregnant, is over 50 years old, or has diabetes. Symptoms that require a 911 response include:
- Chest pain, pressure or discomfort
- Inability to move one or more limbs
- Loss of bowel control
- Loss of speech
- Pounding or irregular heartbeat
- Tongue trauma
- Visual disturbances
Fainting cannot always be prevented. However, patients can take various steps to help reduce the likelihood of fainting episodes by avoiding any triggers that have caused fainting in the past. In addition, eating regularly and drinking plenty of water can help keep blood pressure from dropping while also helping minimize blood pressure changes that occur due to shifts in body position.
The likelihood of fainting may also be reduced by rising slowly from a lying or sitting to a standing position. This gives the body time to adjust to position changes.
In addition, new research shows that fainting spells may be reduced or alleviated in some individuals by practicing a group of simple muscle-tensing exercises.
Questions for your doctor regarding fainting
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about fainting:
- What is causing me to faint?
- Can fainting ever be harmless?
- Does my fainting indicate a serious problem?
- Is it possible that my fainting is related to a mental disorder?
- What tests will you perform to diagnose the cause of my fainting? How should I prepare? When can I expect the results?
- Are there signs or symptoms I should be on the lookout for that might indicate I am about to faint?
- Should I stop driving or engaging in any other activities until the cause of my fainting is determined?
- What should I do if I think I am going to faint?
- What should I do if someone faints near me?