In one aspect the invention provides an adherence monitoring device for a medication delivery device, the monitoring device including at least one inductive coil sensor which includes at least one inductive controller, at least two inductive coils including a first inductive coil coupled to the housing and a second inductive coil coupled to the housing. The first inductive coil is configured to exhibit a response to an inductive change and provide a first change signal in response to an inductive change, and the second inductive coil is configured to exhibit a response to the inductive change and provide a second change signal in response to the inductive change. The monitoring device also includes a processor configured to receive sensor data from the inductive controller representative of the first and second change signals provided by the first inductive coil and second inductive coil and to compare at least one characteristic of the first change signal and the second change signal to detect the occurrence of a medication usage event or a false triggering event.