A situation where someone experiences harmful effects from the application of a drug.
Drug effect contrary to what is therapeutically intended.
In pharmacology and therapeutics, an undesired side effect or toxicity caused by a treatment. Adverse reactions may occur as a result of drug therapies, physical therapy, radiation, or surgery. The onset of the unwanted effect may be immediate or may take days or months to develop. One common type of adverse reaction is an adverse drug reaction (ADR). ADRs are reportable to the federal Food and Drug Administration.
An adverse reaction to a medicinal substance that was administered at the appropriate therapeutic dose may ensue.