If you have a history of fainting and have been evaluated medically, follow your doctor's instructions for how to prevent fainting episodes.
For example, if you know the situations that cause you to faint, avoid or change them.
Avoid sudden changes in posture. Get up from a lying or seated position slowly and gradually. When having blood drawn (if this makes you faint), tell the technician and make sure that you are lying down.
Immediate treatment for someone who has fainted includes:
Checking the person's airway and breathing. If necessary, begin rescue breathing and CPR.
Loosening tight clothing around the neck.
Keeping the affected person lying down for at least 10 - 15 minutes, preferably in a cool and quiet space. If the person cannot lie down, have him sit forward and lower his head below the levels of the shoulders, between the knees.
If vomiting has occurred, turning the person onto one side to prevent choking
Elevating the feet above the level of the heart (about 12 inches).