Fainting  
Every Monday morning we seem to see a patient who faints on the subway.  It always seems to be a healthy young person, usually a woman, with low blood pressure. Fainting is actually a protective device that the body uses to protect the brain from inadequate blood flow.  Many things can cause the blood pressure to drop—a warm room, alcohol, not eating, pain, dehydration from not drinking enough fluids, being out in the sun, sunburn, fever, fluid loss from diarrhea or vomiting, or getting up at night to urinate.  In addition, the site of blood, an emotional response to news, or even the response to blood drawing can cause a drop in blood pressure.  This is called a vaso-vagal response.       

If an individual feels lightheaded, like one might faint, the body is sending a signal that there is not enough blood flow to the brain.  This is a signal for you  to make it easier to get blood to the brain!  Lay down, or at least put your head and your heart at the same height so that the heart does not have to pump against gravity!  It is better to lie down on the floor of a subway than it is to faint on a subway!    It may take 45 minutes before the body resets itself after a vaso-vagal episode.  Stay down.  The most common mistake is to get up too early, resulting in another fainting-like episode.  The key is to recognize the feeling that precedes fainting .  Fainting can lead to head trauma, broken teeth, drowning in showers,  and other potentially fatal events.  Treat it as a warning sign, and respond accordingly. There are many other causes of fainting.  Irregular heartbeats, rapid heartbeats, slow heartbeats, heart block, can cause lightheadedness.    

It is always appropriate to call if there is a fainting episode, especially if you are not a young healthy woman with low blood pressure.  But in many cases it is not necessary for you to worry!