Irritation due to sinus problems, sneezing or allergies can cause nosebleeds, notes the National Institute of Health. Extremely dry air, nasal decongestant spray overuse, a deviated septum or nose injury can also cause nosebleeds. In some cases, certain medications or diseases can also trigger nosebleeds.
It is usually possible to stop nosebleeds by leaning forward while pinching the nose for about 10 minutes. Applying ice to the nose bridge can also help stop a nosebleed. Although most nosebleeds are not life-threatening, patients should visit a doctor if the nosebleed continues for over 20 minutes, according to the National Institute of Health.