Also found in: Acronyms.
any undesirable or unwanted consequence of a preventive, diagnostic, or therapeutic procedure or regimen.
any harmful, unintended effect of a medication, diagnostic test, or therapeutic intervention.
Adverse EffectMalpractice An injury caused by medical management—rather than by the underlying disease—which prolongs hospitalization, produces a disability at the time of discharge, or both.
Aetiology Drug effects, wound infections, technical complications, negligence, diagnostic or therapeutic mishaps, and events occurring in A&E.
Therapeutics An undesirable and unintended, although not necessarily unexpected, result of therapy or other intervention—e.g., headache following spinal tap or intestinal bleeding associated with aspirin therapy.
Toxicology An abnormal or harmful effect on an organism due to exposure to a chemical or noxious substance. Adverse events cause functional or anatomic damage, irreversible changes in homeostasis, or increased susceptibility to other chemical or biologic stress.
Clinical findings Change in food or liquid consumption, body or organ weight, enzyme activity, visible illness or death. Nonadverse effects usually fade when the organism is distanced from the toxin.
Trial Any undesirable symptom, occurrence or effect which a trial subject experiences during the trial, which may or may not be related to the study agent or intervention.
Examples Unfavourable and unintended reactions or findings—e.g., abnormal lab results, symptoms, or disease temporally associated with the use of a medicinal (investigational) product, whether or not it actually is related to the product.
The term adverse effect is often used interchangeably with adverse reaction, which might be better reserved for clinical phenomena occurring during drug treatment when causality cannot be or is not ascertained.
ad·verse re·ac·tion(ad-vĕrs' rē-ak'shŭn)
Any undesirable or unwanted consequence of a preventive, diagnostic, or therapeutic procedure or regimen.