No cold and runny nose is related to allergic rhinitis, sinusitis, nasal polyps, etc. Standardized examination is needed to clarify the specific cause. 1. Allergic rhinitis: allergic rhinitis is related to genetic factors and environmental factors; it can have a large amount of watery nasal mucus, accompanied by nasal congestion, itchy nose, sneezing, smell disorders and other adverse symptoms. 2. Sinusitis: Sinusitis is related to nasal diseases, medical infections, and infections of neighboring organs; it also has symptoms of runny nose, often mucopurulent nasal mucus, pus, and a small amount of blood in the nasal mucus; it can also lead to nasal congestion, head and face distension, and olfactory disorders. 3. Nasal polyps: Nasal polyps are related to aspirin intolerance, genetic factors, and metabolic reactions, which can lead to the phenomenon of a runny nose without a cold. If you have no cold or runny nose, you should actively consult the doctor to clarify the cause.