A slight nosebleed usually stops by itself. If bleeding continues or is severe, put the person in a chair and loosen any tight clothing around his neck. Apply cold compresses to his nose and the back of his neck. It helps to press the skin on the outside of the nostril against the bony carilage, in effect closing the bleeding nostril, for about five minutes. Or plug up the bleeding nostril with sterile cotton. Keep the person sitting, unless he feels faint. If bleeding persists, call a doctor.