Place the nose between the thumb and forefinger, keeping steady, tight pressure. Keep your child quiet and in a sitting position. Instruct him or her to spit the blood out and not swallow it, as swallowed blood can cause nausea and vomiting. If your child has repeated nosebleeds, apply a small amount of Vaseline into the affected nostril once daily for five days to lubricate the mucus membrane. During dry winter months, adding humidity to the air with a vaporizer or humidifier will also help.