Which is stronger? Fonase or nasonex (mometasone)?

About the same. Topical nasal steroids have about equal efficacy (activity) and safety. Flonase (fluticasone) and Nasonex (mometasone) are about the same. It depends on what your physician gets into the habit of using. Also some patients prefer one over the other because one of the two topical sprays is less irritating. There is little evidence that one is better than the other.