An improved breath coordinated inhaler (10) is provided for administering medication to a patient in aerosol form for respiratory inhalation therapy. The improved inhaler (10) comprises a compact housing (18) adapted to receive and support a medication canister (12), including a valve assembly (14) actuated to deliver a dosage of the medication in aerosol form. The housing (18) includes a plunger mounted at a first end thereof for displacing the canister against a spray nozzle (24) located at a second end of the housing to actuate the valve assembly (14), and deliver the medication through a mouthpiece (26) to the patient. The plunger (36) is associated with a seal arrangement for venting the housing (18) when the plunger is depressed to allow the patient to draw in air in timed relation to the medication delivery, and to substantially reseal the housing (18) against ingress of contaminants when the plunger (36) is released.