Please locate a good Allergist in your city and get Allergy Skin Prick Testing done on your son, to identify the offending allergens. Then if the allergen is unavoidable, he should undergo Sublingual Immunotherapy for the same. This is a long term treatment, sometimes lasting up to 5 years, but it is the only sure-shot cure for polyps. Polyp surgery should be done only of nasal passage is being blocked or smell sensation is being affected, but it is only a temporary remedy.