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Adverse effects or events


Adverse drug reaction

An appreciably harmful or unpleasant reaction, resulting from an intervention related to the use of a medicinal product, which predicts hazard from future administration and warrants prevention or specific treatment or alteration of the dosage regimen or withdrawal of the product.

Adverse effect

As for adverse drug reaction, but applied to all interventions, not just drug interventions.

Adverse event

An adverse outcome occurring during or after the use of a drug or other intervention but not necessarily caused by it.

Safety, tolerability, serious, severe

The safety of an intervention relates to its potential to cause serious adverse effects.

Tolerability relates to medically less important but unpleasant adverse effects of drugs. These include symptoms such as dry mouth, tiredness, etc, that can affect a person's quality of life and willingness to continue the treatment.

A serious adverse effect is one that has significant medical consequences, such as death, permanent disability, prolonged hospitalisation. Indirect adverse effects, such as traffic accidents, violence, and damaging consequences of mood change, can also be serious.

Severe refers to the intensity of a particular adverse effect. For example, a non-serious adverse effect, such as headache, may be severe in intensity (as opposed to mild or moderate). A non-serious effect, such as impotence, can have disastrous consequences for a person's quality of life.