1 year old 7 months baby nasal congestion phlegm may be sinusitis, but also colds, allergic rhinitis and so on. 1. Sinusitis: this disease is an inflammation of the mucous membrane of the sinuses, which can be manifested as nasal congestion, runny nose, decreased sense of smell, and older children may express symptoms of headache. If the nasal mucus flows backward to the back wall of the pharynx, it may show the symptom of phlegm. 2. Cold and flu: this disease is a common disease in children, which can be manifested as nasal congestion, clear or yellow runny nose, cough, cough phlegm, sore throat or itchy throat, fever and other symptoms. 3. Allergic rhinitis: often triggered by contact with allergic substances, manifested by frequent sneezing, nasal congestion, a large amount of watery nasal discharge, nasal itching, if the nasal discharge backflow can also be manifested as a symptom of phlegm in the throat. 1 year old 7 months baby nasal congestion, phlegm may also have other reasons, need to consult a doctor in a timely manner, under the guidance of a doctor to clarify the cause of the disease, so as not to miss the condition.