Drugs.com explains that adults may use Nasonex to treat nasal polyps, while children as young as 2 may use Flonase to treat allergies. Nasonex is a brand name, but it also falls under the generic name mometasone nasal. Flonase has the generic name fluticasone nasal and another brand name, Veramyst. Nasonex and Flonase use different types of steroids to prevent the release of substances in the body that cause inflammation.
While Drugs.com carries a warning for people with liver disease to not use Flonase, it does not carry that same warning for users of Nasonex. Nasonex also has potential side effects, such as sores in the nose that do not heal and wheezing or trouble breathing. Flonase has unique side effects including redness, sores or white patches in the mouth or throat, noisy breathing, runny nose or crusting around the nostrils. Nasonex may also include a less serious side effect of nausea, but Flonase users may experience back pain, minor nose bleeds, menstrual problems, loss of interest in sex, sinus pain, cough or sore throat.
Drugs.com also mentions that patients must avoid getting Nasonex in the eyes but that any Flonase users must avoid getting the medication in their eyes and mouths.