Adverse effect: An adverse effect is an unwanted effect associated with treatment. In patient-facing copy, it often overlaps with “side effect”, though formal pharmacovigilance writing may be more specific.

Important for balanced education and informed decision-making.

NICE expects prescribers to discuss harms as well as potential benefits.

Effects may depend on dose, route, other medicines and individual sensitivity.

Related glossary terms

Related MCPH pages

Sources