A nosebleed, also known as epistaxis, occurs when the blood vessels in the nasal lining break, leading to bleeding from one or both nostrils. This condition can be caused by various factors, including dry air, allergies, nasal injuries, or frequent nose-picking. Most nosebleeds are not serious and can be managed at home. To treat a nosebleed, it is recommended to sit upright and lean slightly forward to prevent swallowing blood. Pinching the nostrils together for about 10 minutes can help stop the bleeding. If a nosebleed lasts longer than 20 minutes or occurs frequently, medical attention may be necessary.