A dosage device capable of delivery of a full dosage of medicament to a person in need of treatment through the mouth comprising a storage chamber for more or less temporarily storing the medicament after receiving the medicament from a suitable dispenser, such as an MDI inhaler, and a mouthpiece having a sealing ring for sealing the mouthpiece within the mouth of the person using the dosage device connected to the storage chamber in which a one way valve is located intermediate the storage chamber and mouthpiece to prevent air exhaled by the person from re-entering the storage chamber to reduce or prevent the risk of contamination or cross-contamination occurring within the storage chamber thereby allowing repeated use of the dosage device even by different persons, without the absolute need to clean the dosage device after each use.