Upper respiratory tract infections can potentially cause bleeding. The so-called upper respiratory tract refers to the part of the respiratory tract from the throat upwards to the nose. It is highly susceptible to respiratory viruses such as rhinovirus, influenza virus, and parainfluenza virus, making it particularly prone to infection symptoms, also commonly referred to as the common cold. When the infection is severe, it can cause bleeding on the surface of the respiratory tract. For example, there may be blood in the nasal mucus or in the phlegm when coughing. These are symptoms caused by the infection and increased vascular permeability. Therefore, there is no need for excessive fear. Generally speaking, a respiratory tract infection can heal on its own within 7-10 days, and the bleeding symptoms will also improve as the infection resolves.