An oscillating positive expiratory pressure apparatus having a housing defining a chamber, a chamber inlet, a chamber outlet, a deformable restrictor member positioned in an exhalation flow path between the chamber inlet and the chamber outlet, and an oscillation member disposed within the chamber. The deformable restrictor member and the oscillation member are moveable between an engaged position, where the oscillation member is in contact with the deformable restrictor member and an disengaged position, where the oscillation member is not in contact with the deformable restrictor member. The deformable restrictor member and the oscillation member move from the engaged position to the disengaged position in response to a first exhalation pressure at the chamber inlet, and move from the disengaged position to an engaged position in response to a second exhalation pressure at the chamber inlet.