This invention is for nasal adaptors for oral inhaler devices and methods of adapting an oral inhaler device with a nasal adaptor. The nasal adaptor of the present invention, in assembly with an oral metered dose aerosol inhaler converts an oral inhaler device to nasal delivery. The nasal adaptor in assembly with an oral inhaler device when in operation, simultaneously administers an inhalant to the nasal mucosa and down to the bronchial tree and lungs. In this manner a nasally delivered anti-inflammatory agent would travel down the same route as an allergen would--the nostril, nasal cavity, nasopharynx, trachea, bronchi and lung tissues.