Two most common causes of nose bleed are pricking the nose and hypertension. If one has high blood pressure, this needs to be monitored and if the blood pressure is persistently high, should seek professional assistance. To stop the nose bleed, sit straight and pinch the nose strongly for 10 minutes. This should stop the bleed. If the bleeding recurs or does not stop, you need to visit ER or urgent care clinic. Please read this excellent resource for the details to stop the nose bleed;
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Wishing you a very happy new year.