An adverse reaction (also known as an adverse effect) is an undesired or harmful effect occurring after taking a medication or receiving surgery. Onset may be sudden or develop over time. If this reaction is minor, it may be referred to as a side effect.
Adverse effects are sometimes referred to as "iatrogenic" because they are generated by a physician or treatment. Occasionally adverse effects occur when starting, increasing or discontinuing a treatment. Using a drug or other medical intervention which is contraindicated
may also increase the possibility of adverse effects. Adverse effects commonly cause medical complications of a disease or procedure and negatively affect its prognosis.
Treatment trials, Epidemiology, Association of the British Pharmaceutical Industry (ABPI), Indication, Over the counter (OTC), Concept development and testing, Product pipeline, Continuing Medical Education (CME), Australian Medical Association (AMA), Interventions - clinical, Blind (clinical trial terms), Effectiveness, Cost-minimisation analysis (CMA), Phase IV trials, Persistence,