5. Sinus Infections
Sinus infections are the major causes of nosebleeds, especially during the cold season. If the mind senses that there is an infection in the body, it starts to release histamine. This is a chemical that causes the dilation of blood vessels in order for the immune system to effectively fight the foreign agents causing the infection.
In cases where the infection is in the nose, they become congested and inflamed. Congestion will involuntarily make you blow your nose all the time. This way, the nose lining gets irritated and prone to nosebleed.
Professor Voigt further states that if a person blows their nose, they will be applying too much pressure on the inside nose membrane. That pressure can sometimes push the blood through the small cracks or vessels out of the nose. This may appear as nosebleed, but it would just be blood traces from the irritated blood vessels.