Introduced here are low-cost, disposable inhaler devices that monitor airflow. More specifically, an inhaler device (100) can include a robust airflow sensor (102) and a flow control valve that allows the inhaler device to provide feedback regarding inhalation effort during the administration of medication. The airflow sensor can be disposed within a primary flow channel (104) through which medication travels or a secondary flow channel through which only air travels. Feedback can be transmitted to a computing device (e.g., a mobile phone) in real time. Alternatively, feedback can be recorded to a local memory and then subsequently transmitted to the computing device. Some embodiments of the inhaler device also support a lung capacity check functionality (also referred to as a "spirometry functionality"). These features enable respiratory diseases to be treated more effectively at lower cost.