Causes Nose injury Dryness of inside of the nose due to dry atmospheric weather Hard activity High blood pressure Exposure to high altitudes Blowing your nose too hard What to do if you get a nosebleed Sit down Lean slightly forward to prevent blood from running into your throat. Place cold, wet clothes on your nose to constrict the blood vessels in your nose and stop the bleeding. If blood is coming from only one nostril, press firmly at the top of that nostril. If both nostrils are bleeding, pinch your nostrils together for at least 10 minutes. If bleeding continues, apply pressure for another 10 minutes. If the bleeding is the result of direct injury to the nose, only gentle pressure should be applied. If heavy bleeding persists or if nosebleeds recur frequently, consult a doctor Source: Portal Content Team