Adverse drug reaction
unintended effect due to administration of one or more drugs
An adverse drug reaction (ADR) is an unintended medical event, which can potentially be associated with taking a medication. It can be disadvantageous or beneficial for the patient. ADRs may occur following a single dose or prolonged administration of a drug or may result from the combination of two or more drugs. The meaning of this term differs from the term "side effect" because side effects are proven by thorough investigation to have relationship to the drug. The study of ADRs is the concern of the field known as pharmacovigilance.
An adverse event (AE) refers to any unexpected and inappropriate occurrence at the time a drug is used, whether or not the event is associated with the administration of the drug. An ADR is a special type of AE in which a causative relationship can be shown or is suspected. ADRs are only one type of medication-related harm. Another type of medication-related harm type includes not taking prescribed medications, known as non-adherence. Non-adherence to medications can lead to death and other negative outcomes.
Begin with the source’s own compact description: “Adverse drug reaction” is unintended effect due to administration of one or more drugs. The dossier treats that line as a proposition to test through Adverse, drug and reaction, not as a finished interpretation.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Jul 20, 2026. The linked authority identifier is Q45959. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “Adverse drug reaction” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.