Described here are hand-held, low flow devices for dispensing a therapeutic gas. The devices may be configured to include a gas control assembly for delivering a defined volume of gas at a controlled pressure and flow rate. A nosepiece may be included in the device that is formed of a porous material capable of filtering the dispensed gas, and also diffusing the flow of gas as it travels through the nosepiece and into the nasal cavity. The nosepiece may be configured so that there is substantially no restriction of flow therethrough. Methods for treating various medical conditions and delivering therapeutic gases to the nasal mucosa using hand-held, low flow gas dispenser devices are also described.
