This article updates the practitioner on the pharmacology of antiviral agents. The mechanism of action of the six different classifications of antiviral agents is described. Because influenza and herpes are the viral infections that are most frequently treated in clinical practice, the pharmacotherapeutics of common antiviral agents for these infections are described. This includes pharmacokinetics, adverse effects, preparations, and dosages. Other recommendations related to prescribing and client education surrounding each of the pharmaceutical agents is reviewed.