This course presents the mechanisms of adverse drug reactions (ADRs), the 30 most common ADRs associated with the top 200 drugs dispensed by U.S. community pharmacies, and less common ADRs that relate to dental therapeutics and/or manifest in the head and neck area. Emphasis is on those ADRs that have a pharmacokinetic or a pharmacodynamic basis and, with the exception of overdose, are the result of drug-drug, drug-food, drug-herbal, and drug-disease interactions with therapeutic doses of drugs.