Definition of Complication (medicine)

Complication, in medicine, is an unfavorable evolution of a disease, a health condition or a medical treatment. The disease can become worse in its severity or show a higher number of signs, symptoms or new pathological changes, become widespread throughout the body or affect other organ systems. A medical treatment, such as drugs or surgery may produce adverse effects and/or produce new health problem(s) by itself. A new disease may also appear as a complication to a previous existing disease. Therefore, a complication may be iatrogenic, i.e., literally brought forth by the physician.