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Clinical Review Fortnightly review

Adverse drug reactions

BMJ 1998; 316 doi: (Published 25 April 1998) Cite this as: BMJ 1998;316:1295
  1. Munir Pirmohamed (, senior lecturer in clinical pharmacology,
  2. Alasdair M Breckenridge, professor of clinical pharmacology,
  3. Neil R Kitteringham, senior lecturer in pharmacology,
  4. B Kevin Park, professor of pharmacology
  1. Department of Pharmacology and Therapeutics, University of Liverpool, Box 147, Liverpool L69 3BX
  1. Correspondence to: Dr Pirmohamed

    An adverse drug reaction is any undesirable effect of a drug beyond its anticipated therapeutic effects occurring during clinical use. In contrast, an adverse drug event is an untoward occurrence after exposure to a drug that is not necessarily caused by the drug.1

    When a drug is marketed little is known about its safety in clinical use because only about 1500 patients are likely to have been exposed to it. 1 2 Thus drug safety assessment should be considered an integral part of everyday clinical practice since detection and diagnosis often depend on clinical acumen.

    In this article we review the current status of adverse drug reactions, briefly describing the complexity of the more bizarre reactions and outlining a strategy to eliminate serious adverse drug reactions.

    Summary points

    Adverse drug reactions are a common clinical problem

    They are diagnosed on clinical grounds from the temporal relation between the start and finish of drug treatment and the onset and offset of the reaction

    Pharmacological adverse reactions are generally dose-dependent, related to the pharmacokinetic properties of the drug, and resolve when the dose is reduced

    Idiosyncratic adverse reactions are not related to the known pharmacology of the drug, do not show any simple dose-response relation, and resolve only when treatment is discontinued

    Vigilance by clinicians in detecting, diagnosing, and reporting adverse reactions is important for continued drug safety monitoring


    We conducted a search on the BIDS ISI database between 1981 and 1997 using key words such as toxicity and hypersensitivity combined with drug. The references most relevant to this review were then scanned together with any other relevant references cited within the articles. We also continuously review the literature because of our research interests.

    Importance of adverse drug reactions

    Adverse drug reactions are a major clinical problem, accounting for 2-6% of all hospital admissions (box).3-6 Recent surveys …

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