Background: The design and development of the delivery device component of an orally inhaled and nasal product (OINDP) are complex, requiring the implementation of national regional and international standards to ensure compliance with increasingly rigorous regulatory requirements. Methods: The Device Sub-Team of the European Pharmaceutical Aerosol Group (EPAG) has examined the range of guidance documentation currently applicable to the design and development of all classes of orally inhaled products (OINDPs), with the intention of providing a summary of best practices. Results: A hierarchy of pertinent International (ISO) standards has been identified, covering quality management systems at the highest level, the design/development and risk assessment processes at the next level, followed by detailed device class-specific standards and a separate standard covering biological evaluation at the lowest level. The ‘waterfall’ model developed originally by the USFDA covering the design process from initial ideas through prototype development to commercial product, is enhanced to include a round of assessment post-marketing that checks if patient needs have been met. This addition is in harmony with current regulatory guidance to include human factors throughout the process. Lastly, a mind-map considering the interrelationships between patient needs /user requirements and critical aspects forming the OINDP design input has been developed. Conclusions: The developer of the device component of a new OINDP can make use of the guidance given herein to establish best practices applicable to the user requirements specification for this particular product.