last updated 24-06-2024

Adverse Drug Reactions

Adverse Drug Reactions

An adverse drug event (ADE) is an undesirable event that occurs during treatment with a medicine but is not necessarily caused by the medicine itself.

The WHO defines an adverse drug reaction(ADR) as "a response to a drug that is noxious and unintended, and which occurs at doses normally used in man for the prophylaxis, diagnosis, or therapy of disease, or for modification of physiological function." Hence, ADRs are ADEs that occur due to the pharmacologic properties of the drug. 

Side effects are related to the pharmacological activities of a drug, and are thus an example of ADR. However, side effects can beneficial as well as harmful.

toxic effect differs from an ADR because it is caused by an exaggeration of the desired therapeutic effect and is hence dose-related. An ADR may thus be a toxic effect. Toxicology itself is the study of deleterious effects of physical, chemical, or biological substances, and covers many more agents than drugs.

ADRs are an important topic in pharmacology and medicine, as it is estimated that 6% of all hospital admissions are due to ADRs. It is up to the physician to prevent ADRs as much as possible, and to recognise and adequately manage them when they do occur.