The present invention includes methods and devices for providing safeguards to the access of certain substances. Some implementations provide alerts and/or other appropriate actions when substances are subject to spoilage or expiration. Some implementations provide responses to potentially dangerous combinations of substances. Other aspects of the invention involve determining the allergies of a user and providing a warning when allergens are, or recently have been, present. One preferred embodiment provides a smart medicine cabinet for helping to provide medication safely to a patient and to provide other related services.