Abstract: A nasal cannula of the type to be connected to a fluid duct and positioned within the nose of a patient for administering therapeutic fluid. The cannula comprises a resilient bulbous member configured to fit snugly within and against the vestibule wall of one nasal cavity of the patient to form a tight seal with respect thereto while maintaining the other nasal cavity in communication with ambient surroundings. The bulbous member includes a passage therethrough for communicating the fluid duct with the nasal cavity so that fluid supplied through the duct is inhaled through the one nasal cavity and exhaled through the other nasal cavity and/or open mouth.