An inhaler (10) has a main body for accommodating a medicament reservoir (84), a canister fire system for moving a canister (50) to release a dose in response to air flow, a cap housing (12) for enclosing the canister fire system and canister within an interior chamber defined by the main body (14) and a cap housing, wherein a lock system (250) is provided for locking the cap housing on the main body.
