Aging & Health A to Z
Causes & Symptoms
Fainting is usually caused by a temporary lessening of blood flow to your brain. This can be due to many possible causes, ranging from some that are essentially harmless to some that can be life threatening. Common causes include:
A sudden drop in blood pressure, which your doctor calls orthostatic hypotension. It’s common to occasionally feel lightheaded when you stand up suddenly, but if this happens frequently or results in fainting, it may mean that your body has trouble maintaining a healthy blood pressure. Orthostatic hypotension can be caused by:
- Medications, often those used to treat high blood pressure
- A drop in blood pressure immediately after eating, due to blood “pooling” in your abdomen to help digest food (called postprandial hypotension).
Fainting that is associated with heart problems can be serious. It can be caused by:
- Narrowing of the aortic heart valve (aortic stenosis)
- Irregular heart rhythms, particularly an unusually low heart rate (bradycardia)
- Heart failure
- Heart attack.
Conditions of the Brain or Nervous System
This includes strokes, narrowing of the blood vessels in the brain, or seizures. Some signs of these conditions are dizziness, visual problems, loss of bladder control, inability to sweat, difficulty tolerating the heat, constipation, chronic fatigue, or impotence.
As you age, your kidneys don’t function as well as they used to, and you don’t always drink enough liquids. This can lead to dehydration and a drop in blood volume, which can lower your blood pressure. As you age, your thirst mechanism does not work well either and your body does not tell you when you become dehydrated. This can result in a drop in blood volume without the realization that you should drink something.
Sometimes syncope is related to an oversensitivity of the pressure sensors in the carotid arteries in your neck (called carotid sinus hypersensitivity). You may aggravate this if you wear tight collars, turn your head and neck too suddenly, or take certain medications.
Updated: March 2012
Posted: March 2012