Rhinitis is divided into acute rhinitis, chronic rhinitis, 9 months baby runny nose nasal congestion half a month may get acute rhinitis. Chronic rhinitis can be caused by the autoimmune system or endocrine, genetic and other causes of chronic inflammation of the nasal mucosa, mostly recurring episodes, which can last for several months, simply have a runny nose, nasal congestion for half a month, can not be diagnosed as the disease, but it is likely to get acute rhinitis. Acute rhinitis is caused by respiratory viral infection acute inflammation of the nasal mucosa, mostly due to cold, low immunity and other triggers of the disease, can show a runny nose, nasal congestion, sneezing and other symptoms, early watery nasal mucus, late pus can appear. Acute rhinitis can generally be cured in about 7 to 10 days, the younger ones can last longer, such as the combination of pneumonia and other complications, up to more than half a month to a month of time. Nine-month-old baby runny nose nasal congestion for half a month, the need for timely medical treatment, so as to avoid further development of the condition.