A multi-function oxygen mask is disclosed which generally comprises a mask body and a gas delivery adapter. The mask body forms an internal cavity configured to cover a nose and mouth of a patient. A nasal chamber is formed in the upper portion of the mask body, the nasal chamber includes an upper portion, a lower portion and a gas delivery adapter aperture adjacent the lower portion of the nasal chamber. An access aperture is formed through and adjacent to the lower portion of the mask body. The access aperture is configured to permit access to the mouth of a patient. The gas delivery adapter has a general tubular structure and includes a first end and opposing second end, the first end of the gas delivery adapter is coupled to the gas delivery adapter aperture. An oxygen supply port radially extends outward from the gas delivery adapter and adjacent to the first end of the gas delivery adapter. The oxygen supply port further includes an external inlet portion, an outlet portion positioned within a volumetric space of the gas delivery adapter and a diverter member adjacent to the outlet portion. The diverter member is configured to direct a flow towards the first end of the gas delivery adapter. A meter-dose inhaler port radially extends outward from the gas delivery adapter. Finally, the gas delivery adapter includes a meter-dose inhaler port and a nebulizer port.