Sudden flow of yellow water from the nose may be caused by the rupture of sinus cysts, nasal vestibule eczema and other reasons. 1. Sinus cyst rupture: mucous membrane cysts appear in the sinuses, the cysts gradually become bigger and even rupture, which discharges yellowish liquid, the cyst fluid through the sinus outflow, which leads to a sudden flow of yellow water in the nose. 2. Nasal vestibular eczema: Nasal vestibular eczema will appear more obvious itching, there will be local erythema, small corn-like papules, blisters, if the patient scratching, papules and blisters will burst, thus appearing the symptoms of the nose suddenly flowing yellow water. Patients with yellow water suddenly flowing from the nose should go to the regular hospital in time to identify the cause of the disease and take targeted treatment measures under the guidance of professional doctors.