Why does a cold cause yellow nasal discharge?
Disease description:
Recently, the weather has been cold, and I caught a chill, resulting in a runny nose. The nasal discharge is yellow. I would like to ask the doctor, what causes a runny nose with yellow mucus when having a cold?
Doctor's answer (1)
Dr. Yang Ziqi
Yellow nasal discharge during a cold is usually caused by an upper respiratory tract infection due to a viral infection. Initially, nasal discharge may be clear, but as the illness progresses, the body's immune system releases white blood cells, including neutrophils, to fight the virus. These neutrophils release yellow or greenish peroxides during this process, causing the nasal discharge to change color. This typically indicates that the infection is resolving, as neutrophils are attempting to clear the pathogens.
Besides viral infections, bacterial infections can also cause yellow nasal discharge, although this is relatively less common. If accompanied by other symptoms such as high fever, thick yellow-green nasal discharge lasting several days, headache, or facial tenderness, antibiotic treatment might be necessary.
Please note, if symptoms persist or worsen—for instance, if fever lasts more than three days—prompt medical attention is advised.
