Allergic rhinitis (AR) is characterized by mucosal inflammation, therefore anti-inflammatory drugs are indicated for its treatment, mainly concerning intranasal administration. Mometasone furoate nasal spray (MFNS) has been on the market under the brand Nasonex® for 20 years and has high effectiveness and an excellent safety profile. From a clinical point of view, an ideal topical medication should respect a series of requirements, including handy device, good sensory characteristics, aptitude to the reach posterior nasal cavity, long residence time, and optimal pharmacokinetic and pharmacodynamic activities. MFNS fully satisfies these claims, as underlined by 20 years of worldwide prescriptions.