Expand Document  |  Expand Chapter  |  Full TOC  |  Printable HTML version
Safety of Medicines - A Guide to Detecting and Reporting Adverse Drug Reactions - Why Health Professionals Need to Take Action
(2002; 16 pages)
Table of Contents
View the documentIntroduction
View the documentGlossary
View the documentThe magnitude of the problem
View the documentWhy postmarketing surveillance and reporting ADR is needed
View the documentWhy pharmacovigilance is needed in every country
View the documentHow voluntary reporting on ADRs can prevent new medicine tragedies from developing
View the documentHow voluntary reporting on ADRs can influence labelling
View the documentWhy health professionals are in the best position to detect and report on ADRs
View the documentHow to recognize ADRs
View the documentWhat should be reported?
View the documentHow to report ADRs?
View the documentReferences
View the documentAcknowledgements


The terms are from “Safety Monitoring of Medicinal Products”1

1. An adverse drug reaction (ADR) is a response to a medicine which is noxious and unintended, and which occurs at doses normally used in man'.

In this description it is of importance that it concerns the response of a patient, in which individual factors may play an important role, and that the phenomenon is noxious (an unexpected therapeutic response, for example, may be a side effect but not an adverse reaction).

2. An unexpected adverse reaction is ‘an adverse reaction, the nature or severity of which is not consistent with domestic labelling or market authorisation, or expected from characteristics of the drug’.

3. A drug or medicine is 'a pharmaceutical product, used in or on the human body for the prevention, diagnosis or treatment of disease, or for the modification of physiological function'.

4. A side effect is 'any unintended effect of a pharmaceutical product occurring at doses normally used by a patient which is related to the pharmacological properties of the drug'.

Essential elements in this definition are the pharmacological nature of the effect, that the phenomenon is unintended, and that there is no deliberate overdose.

5. An adverse event or experience is defined as 'any untoward medical occurrence that may present during treatment with a medicine but which does not necessarily have a causal relationship with this treatment'.

The basic point here is the coincidence in time without any suspicion of a causal relationship.

6. A serious adverse event is any event that:

• Is fatal
• Is life-threatening
• Is permanently/significantly disabling
• Requires or prolongs hospitalization
• Causes a congenital anomaly
• Requires intervention to prevent permanent impairment or damage

7. A signal refers to 'reported information on a possible causal relationship between an adverse event and a drug, the relationship being unknown or incompletely documented previously'.

Usually more than a single report is required to generate a signal, depending upon the seriousness of the event and the quality of the information.

to previous section
to next section
The WHO Essential Medicines and Health Products Information Portal was designed and is maintained by Human Info NGO. Last updated: October 29, 2018