An apparatus for prompting the actuation of a metered dose inhaler (1, Fig 1), the apparatus comprising airflow responsive means 16 which is, in use, mounted on the inhaler and provides the user with an indication that the flow of air through the airway of the inhaler satisfies a predetermined criterion, for example a predetermined pressure drop in airflow through the airway, thereby to prompt the user to actuate the dispenser. The airflow responsive means 16 is preferably moveably mounted on the inhaler to interact with the flow of air created by the user inhaling through the airway, so as to be moved by the flow said movement constituting the indication. A further apparatus is also taught for restricting the flow of air that passes through the airway, thus increasing the pressure drop of air flowing along the airway so as to prevent a user from inhaling too rapidly.
