Adverse Drug Events

Medication Error: any preventable event that may cause or lead to inappropriate medication use or patient harm while the medication is in the control of the health care professional, patient, or consumer.

Side Effect: is a secondary effect that occurs after using a medication. These are well documented and often anticipated when the medication is prescribed. Side effects are often undesired effects caused by the medication (e.g., nausea after taking metformin); however, some side effects may be beneficial (e.g., weight loss after taking metformin). In this example, both nausea and weight loss are expected when metformin is prescribed with the knowledge that the nausea often dissipates after time. When referring to injury or harm resulting from medication use, the terms Adverse Drug Event or Adverse Drug Reaction are preferred.

Adverse Drug Event (ADE): is an unwanted effect or harm that occurs after using a medication where the medication is suspected as the cause. An adverse event can result from a medication error but often occur with appropriate medication use. Adverse Drug Reaction (ADR): is an adverse drug event which is proven to be directly caused by the medication at normal doses and with normal use.

Allergies: allergies are an ADE that are mediated by an immune response. Serious Adverse Drug Events/Reactions: are those that result in death, require hospital admission or prolongation of existing hospital stay, result in persistent or significant disability/incapacity, or are life threatening.

Unexpected Adverse Drug Events/Reactions: are those that occur but are not found labeled in the package insert, pharmacologic references, or in the medical literature or that occur in a patient where the effect is unexpected.