A fainting spell can be a frightening experience. The brief loss of consciousness associated with fainting can trigger significant anxiety in the person unfortunate enough to experience it. The good news is that a fainting spell is usually not associated with a serious underlying medical problem and is unlikely to cause lasting harm unless an injury occurs during the episode. What causes fainting spells to occur?
What Causes Fainting Spells?: Vasovagal Syncope
The most common type of fainting spell in a healthy person is known as vasovagal syncope. This occurs when the nervous system signals the blood vessels in the legs to dilate, causing blood to pool in the lower extremities. At the same time, the blood pressure drops and there is a brief loss of consciousness. A fainting spell of this type can be brought on by a variety of triggers including fear, stress, coughing, pain, or the sight of blood. One common cause of vasovagal syncope, particularly in older people, is straining at the toilet. A fainting spell of this type is known as micturition syncope.
What Causes Fainting Spells?: Low Blood Sugar and Low Blood Volume
Another fairly common cause of a fainting spell is low blood sugar. This can be a life threatening problem if it occurs in a diabetic who takes insulin. Fainting in a diabetic requires an immediate source of sugar to raise blood sugar levels and provide nourishment to the brain. This is why diabetics are encouraged to carry a sugar source with them at all times. Fainting can also occur when the volume of blood pumped by the blood vessels is reduced due to dehydration, heavy bleeding, excessive diarrhea, or vomiting.
What Causes Fainting Spells?: Orthostatic Hypotension
Some people experience a fainting spell when they get up from a sitting or lying position too quickly. This type of fainting spell arises from orthostatic hypotension where the blood vessels in the legs dilate and don’t return blood to the heart properly causing the blood pressure to drop quickly. This can be made worse by dehydration or warm temperatures. This type of fainting spell becomes more common with age.
What Causes Fainting Spells?: Medications
An often overlooked cause of a fainting spell is medications. A variety of medications can increase the risk of a fainting spell. These include certain types of blood pressure medications, medications used to treat heart conditions, and some drugs used to treat mood disorders.
More Serious Causes of a Fainting Spell
Although fainting is not generally a sign of a serious medical problem, it can be caused by an excessively slow or irregular heart rhythm. It may also indicate the presence of undiagnosed heart disease. For this reason, if a fainting spell occurs for no apparent reason, it’s important to see a doctor. In some cases, fainting can be difficult to differentiate from a seizure, another cause of loss of consciousness.
The Bottom Line?
Fainting that occurs with no obvious trigger or frequent fainting spells should be evaluated by a doctor. In most cases, no serious cause will be found, but why take a chance?
