What is the most common cause of nosebleeds?

The most common cause of nosebleeds is external trauma. This can include a variety of incidents such as picking the nose, blowing the nose too forcefully, or sustaining an injury. The nasal lining is rich in blood vessels, making it particularly susceptible to bleeding when disturbed. Even minor trauma can lead to a bleeding episode, which is why external trauma is far more prevalent as a cause compared to other factors.

While sinus infections, allergic reactions, and high blood pressure can contribute to nosebleeds in certain situations, they are not as frequent as trauma. Sinus infections can cause inflammation and increased nasal pressure, potentially leading to bleeding, but this is not as common as the direct effect of trauma. Similarly, allergic reactions may result in nasal irritation and subsequent bleeding, but again, this is less frequent than the direct injury to the nasal passages caused by external trauma. High blood pressure can sometimes lead to nosebleeds, especially if it is severely elevated, but it is not a common cause in the general population. Therefore, external trauma stands out as the primary reason for most nosebleeds.