Six-month-old baby with runny nose should be medicated according to the cause of the runny nose, usually acute upper respiratory tract infection caused by common respiratory viral infection, causing nasal mucous membrane congestion, nasal secretions, so runny nose. Treatment is mainly oral antiviral drugs such as antiviral oral solution, can also use interferon spray or ribavirin spray local spray throat antiviral treatment, can also eat some pediatric cold punch to reduce the symptoms. If your baby has frequent recurrent episodes of runny nose, he may have chronic rhinitis, sinusitis, allergy-related diseases, the main thing is to look for allergens and avoid repeated intake and contact of allergens in order not to have recurrent episodes. You can take oral anti-allergy medications such as cetirizine hydrochloride drops or loratadine during the obvious runny nose, and you can use saline nasal spray to cleanse nasal secretions.