The difference is Flonase is available over-the-counter (OTC) and Nasonex is prescription only. There is no difference in their effect or side effects.

Flonase and Nasonex are both corticosteroid nasal sprays that are effective at treating hay fever, perennial allergic rhinitis and allergies. Nasonex is also FDA approved to treat nasal polyps. Flonase contains fluticasone and Nasonex contains mometasone; these are both glucocorticoid corticosteroids that help to relieve congestion, sneezing, postnasal drip, and other allergy symptoms, including eye symptoms.

Only Flonase is available OTC

Flonase is available over-the-counter, at the same strength as its prescription counterpart. At the time of writing (Sept 2016), Nasonex was only available by prescription. Both provide 24-hour relief of allergic rhinitis symptoms that is free from drowsiness. Regardless of which one you use it will take several hours before you feel any effects from the spray, and several days of regular use before the full effect is seen. This is why experts recommend you use a corticosteroid nasal spray from the start of the allergy season until the end, not just when you get a flare up of symptoms, in order to get the best results.

Flonase Vs Nasonex: Effectiveness and Side Effects

Several trials have shown that both fluticasone (Flonase) and mometasone (Nasonex) nasal sprays are equally effective, safe, and well tolerated for the treatment of allergic rhinitis.

Side effects caused by Flonase and Nasonex are similar and include a headache; stinging, burning or bleeding in the nose; a sore throat and watery eyes. The American Academy of Asthma, Allergy and Immunology (AAAI) warns that fluticasone nasal sprays (Flonase) do slow growth rate in children; one large study of 474 children reported an average slowing of 0.27 cm/year (as much as 0.48 cm and as little as 0.06 cm). While other studies that investigated mometasone (Nasonex) did not find it slowed growth rate, it is likely that numbers of participants in these trials were too few to show a difference. All children receiving intranasal corticosteroids for longer than two months should be monitored for any slowing of growth rate.

Flonase Vs Nasonex: Formulations

Flonase Allergy Relief delivers 0.05mg (50 microgram) fluticasone per spray. Children's Flonase Allergy relief also delivers 0.05mg (50 micrograms) fluticasone per spray - the same dose, but there are fewer sprays per bottle so it is less expensive. Neither the Flonase Allergy Relief nor the Children's Flonase Allergy relief should be used in children under the age of four. However, Flonase Sensimist Allergy Relief which delivers 0.0275mg (27.5microgram) fluticasone per spray may be used in children aged two to four.

Nasonex Nasal Spray has one strength, 0.05mg (50 micrograms) mometasone per spray and can be used by adults and children over the age of two.

Bottom Line

In summary, choice of either Flonase or Nasonex comes down to personal preference, availability (only Flonase is available OTC) or price, as there is no difference in their effect or side effects. Both Flonase and Nasonex are available as generics.

See also:

• Drugs.com Compare Tool - Flonase vs Nasacort