An osmotic device for delivering a beneficial drug, such as an anti-fungal, into the mouth of a human patient is disclosed. The device has a size and shape adapting it to be comfortably retained in the mouth for extended periods of time. The device comprises a wall surrounding a compartment housing a layer of an agent that is insoluble to very soluble in aqueous biological fluid, e.g., saliva, and a layer of a fluid swellable, hydrophilic polymer. A passageway in the wall connects the agent with the exterior of the device. The wall is permeable to the passage of aqueous biological fluid but substantially impermeable to the passage of the hydrophilic polymer. In one embodiment the beneficial agent has a different color than the hydrophilic polymer. The wall is sufficiently translucent to permit the patient to see the amount of drug/beneficial agent remaining to be delivered. Marking lines may be provided on the wall indicating the amount of drug/agent which has been delivered and/or the amount remaining to be delivered.