Summary: Antimicrobials that are available over-the-counter (OTC) cause problems for physicians treating patients with febrile neutropenia because they have been shown to be associated with increasing emergence of resistance due both inappropriate use and overuse. Self-diagnosis by patients is often inaccurate and the availability of OTC antimicrobials enables this to continue. Often patients present to physicians with no knowledge of the agent or class of agent they have taken, or may even completely fail to mention taking such agents. This is of special concern if taken in the 3 months prior to developing febrile neutropenia as it is recognized that such administration is associated with increased resistance to the earlier antimicrobial or class of drug taken. In addition, many patients are unaware or have forgotten the dose of drug taken, or how often or regularly it was taken. The lack of full documentation of OTC use makes correct diagnosis and subsequent treatment by physicians more difficult and adds to the problem of growing resistance and reduced outcomes.