A seven-month-old baby with a runny nose may have an acute rhinitis if the symptoms have not been present for a long time. When you have a cold or an upper respiratory tract infection, you may have an acute rhinitis with a blocked nose, a runny nose, sneezing and so on. If the period of time is longer, such as several months, there may be the possibility of chronic rhinitis, which will also have a blocked nose and clear nasal discharge. There is also the more common allergic rhinitis. Seven-month-old babies can get allergic rhinitis as well, which can be seasonal or perennial. When the symptoms are obvious, there will be itchy nose, sneezing, runny nose, blocked nose and so on. If it is prolonged, you can rinse the nasal cavity with physiological seawater, there is a special rinse for infants, you can nasal spray hormone, with a special nasal spray hormone drugs for infants. If the symptoms are severe, you can also use some antihistamines to combat allergies.