Nosebleeds from colds can be caused by inflammatory stimuli, external factors, and dryness of the nasal mucosa. 1. Inflammatory stimulation: colds are often caused by viral infections, due to inflammatory factors on the nasal mucosa caused by stimulation, which can lead to nasal mucosa congestion and edema, capillaries are relatively fragile, once a slight stimulus, such as stimulation of cold air, may lead to mucosal rupture bleeding. 2. External factors: in the cold may appear nasal itching, ventilation, increased secretion and other symptoms, the patient may appear picking the nose or rubbing the nose phenomenon, resulting in mucosal rupture nosebleed. 3. Nasal mucosa dryness: cold and flu if the environment is cold or dry may stimulate the nasal mucosa, which will lead to an increase in the brittleness of the capillaries, and when the breakage occurs, it will cause a nosebleed. Nosebleeds can also be caused by other reasons. If you have repeated nosebleeds, you need to go to the doctor in time to get a clear diagnosis and then cooperate with the doctor’s treatment.