Most nosebleeds are unilateral due to the cracking of a capillary in the anterior part of the nose. This type of bleeding constitutes the majority of bleedings. It often occurs in dry climates or in the winter months due to the dry and hot room air, with crusting that occurs as a result of the drying of the mucous membrane covering the inside of the nose. Since the veins in this area are very thin and on the surface, they can bleed from nose blowing, playing with the nose in children, and even with the slightest touch. This type of bleeding is usually unilateral and sometimes bilateral.

 

Source: http://www.kbb.org.tr