Fainting is a sudden and temporary loss of consciousness which develops as a result of insufficient blood supply to the brain. A person soon regains consciousness because while lying down the brain receives more blood. Most people have had a fainting episode at least once. But in case one continues losing his/her consciousness there is a reason to worry and this should be reported to the doctor.
Causes of Fainting
In many cases fainting is harmless and occurs due to the vasovagal reflex. Namely, this reflex leads to severe drop in blood pressure and can be accompanied by brachycardia (slow heart rate). Even though there are many triggers of vasovagal reflex the most common ones are extreme pain or fear. The symptoms of fainting caused by vasovagal reflex are typical and include a sudden onset of nausea accompanied by dizziness or severe lightheadedness. There is also profuse sweating, feeling cold and clammy and one experiences weakness that precedes the loss of consciousness. The vasovagal reflex usually affects people while they are standing although it may also occur in the sitting position. Fainting caused by vasovagal reflex is not a disease and can be explained by inadequate adaptation of reflex mechanisms in charge of heart rate and blood pressure.
Orthostatic hypotension (postural hypotension) is another cause of fainting. In this case blood pressure suddenly falls if the person stands up too fast. Orthostatic hypotension may be additionally induced by the intake of certain medications (particularly antihypertensive drugs) or occurs due to dehydration.
Furthermore, fainting can be a sign of more serious medical conditions such as blood clot in the lungs and several heart conditions including arrhythmia, a heart valve problem and heart disease. The problem is also associated with transitory ischemic attack (TIA) or stoke.
And finally, there are cases when doctors simply cannot identify the actual cause of fainting.
When Is Fainting Serious?
Fainting can be a sign of serious and life-threatening conditions. For example, heavy bleeding (e.g. heavy internal bleeding) leads to fainting once the person has lost a certain amount of blood. The problem becomes even more severe if there are additional symptoms such as shortness of breath, chest pain, palpitations, numbness or tingling sensations of one side of the body etc.
What To Do about Fainting?
Even though fainting can be harmless it is best to consult a doctor who will take medical history, perform a physical and neurological exam and several more tests and exams in order to identify the underlying cause. When the doctor confirms the person is not suffering from a serious medical condition if the same person is prone to fainting he/she may prevent fainting by sitting with the head between the knees or lie down in case there are introductory (earning) signs of fainting such as dizziness, weakness, warmth or nausea.