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.
Brainstorm, Dose-ranging trial, Pandemic, Epidemiology, Phase III trials, Investigational new drug (IND), Adherence, Defined daily dose (DDD), Prescription only medicine (POM), Prophylaxis, Randomised trial, European Union of Medical Specialists (UEMS), Expanded access, Continuing Medical Education (CME), Drug-drug interaction,