Just before fainting, you may feel a sense of dread, followed by the sense that everything around you is swaying. And you may see spots before your eyes. Then you go into a cold sweat, your face turns pale, and you topple over.

A fainting victim may pass out for several seconds or up to 1/2 hour. The cause is a sudden reduction of blood flow to the brain. That reduction can be caused by emotional stress; physical pain; a sudden change in body position, like standing up too quickly (postural hypotension); abnormal heart rhythm; stroke; or heart attack.

Here are some dos and don'ts to remember if someone faints.

Do:

• Catch the person before he or she falls.
  
• Place the person in a horizontal position, with the head below the level of the heart and the legs raised to promote blood flow to the brain. (If a potential fainting victim can lie down right away, he or she may not lose consciousness.)
  
• Turn the victim's head to the side, so the tongue doesn't fall back into the throat.
  
• Loosen any tight clothing.
  
• Apply cold, moist towels to the person's face and neck.
  
• Keep the victim warm, especially if the surroundings are chilly.

Here's what you shouldn't do.

• Don't slap or shake anyone who's just fainted.
  
• Don't try to give the person anything to drink, not even water.
  
• Don't allow the person who's fainted to get up until the sense of physical weakness passes, and then be watchful for a few minutes to be sure he or she doesn't faint again.

If you're prone to fainting spells, ask yourself why. Common faints (not linked to disease) tend to take place in a warm, crowded room, or when your stomach is empty, or when you're in pain, or after an injury. Poor physical condition can leave you more prone to fainting.

If you get dizzy or feel the room is spinning when you stand up or after you have been standing in one position for too long, you're experiencing postural hypotension. To prevent this from happening, try to take your time standing up from a sitting or lying position (count to 60), and don't stand still for long periods of time. Also, check your medications. Blood pressure drugs increase the risk of postural hypotension, and your medication may have to be changed. Or you can wear elastic stockings to increase blood flow from the extremities and help prevent fainting.