To find the cause of fainting, a doctor will do a physical examination and ask questions about the fainting episode. You can help your doctor by being prepared to describe what happened before you fainted, how long you were "out," and how you felt when you woke up.
Depending on what the physical examination shows, the doctor may want to do tests. These tests may include:. If you know you tend to faint at certain times such as when you get a shot or have blood drawn , it may help to:.
You may need to see a doctor if you have ongoing dizziness or fainting. Blahd Jr. Author: Healthwise Staff. Medical Review: William H.
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Top of the page. Topic Overview What is fainting? What causes fainting? In these cases, you faint because of: The vasovagal reflex, which causes the heart rate to slow and the blood vessels to widen, or dilate. As a result, blood pools in the lower body and less blood goes to the brain.
This reflex can be triggered by many things, including stress, pain, fear, coughing, holding your breath, and urinating. Orthostatic hypotension , or a sudden drop in blood pressure when you change position. People over age 60 are more likely to faint for heart-related reasons than those who are younger.
Once the dose is adjusted, you should stop passing out. Of much greater concern is fainting caused by episodes of a slow or fast rate. The most dangerous is a heart rhythm disturbance called ventricular tachycardia , or ventricular fibrillation VFib.
In VFib, your heart fibrillates races away in a disorganized fashion. After four to five seconds, you lose consciousness, stop breathing and have no pulse. This is called sudden cardiac arrest. Sudden cardiac arrest is the most common single cause of death in our country. If you do have any of these risk factors, tell your cardiologist promptly about these fainting spells. If you are found to be at risk of VFib, or of having a sudden cardiac arrest episode, an implantable cardioverter-defibrillator ICD can save your life.
Whenever an episode occurs, the ICD will automatically restore normal heart rhythm — within seconds. During the summer when temperatures are hot, outdoor activities are more abundant and fainting can occur more frequently due to overheating and dehydration. Is it always harmless, or can fainting be a sign of a more serious medical problem? In many cases, fainting is not a reason for concern.
But, in some people — particularly in those with a history of heart problems or those who faint while exercising — fainting may be caused by a more serious underlying medical condition. In those cases, a health care provider should assess it as soon as possible.
One of the most common reasons people faint is in reaction to an emotional trigger. For example, the sight of blood, or extreme excitement, anxiety or fear, may cause some people to faint. This condition is called vasovagal syncope. Vasovagal syncope happens when the part of your nervous system that controls your heart rate and blood pressure overreacts to an emotional trigger.
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