How do i treat my child's chronic runny nose?

Cause is first: First find out the cause -- allergies, constant irritation from tobacco or scented products, or perhaps the 10 URIs children get each year, often back-to-back. Eliminate the possible cause, moisturize the nasal passages, use a humidifier in dry rooms, and try an antihistamine. If not better, your MD may suggest ENT/allergy evaluation.

Workup and mgt: I would suggest an evaluation for chronic sinusitis, allergies and a CF sweat test. Having your child blow her nose into a tissue, the use of pediatric nasal saline and avoiding triggers of the symptoms is also recommended.