Everyone experiences a nosebleed from time to time. The cause may be an impact to the nose, but many times the nose bleeds because of nasal congestion due to a nasal allergy, strep throat, a sinus infection, or a cold that irritates and weakens the delicate nasal lining.

In some adults, especially those taking aspirin or anticoagulants, the bleeding may start spontaneously. However, the main cause of nosebleeds is people picking or irritating the small blood vessels just inside the nose. If you...