In medicine, a<unk>  is an<unk> , whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse<unk> s, it can also apply to beneficial, but unintended, consequences of the use of a drug. Developing drugs is a complicated process, because no two people are exactly the same, so even drugs that have virtually no<unk> s, might be difficult for some people. Also, it is difficult to make a drug that targets one part of the body but that does not<unk>  other parts, the fact that increases the risk of<unk> s in the untargeted parts. Occasionally, drugs are prescribed or procedures performed specifically for their<unk> s; in that case, said<unk>  ceases to be a<unk>  and is now an intended<unk> . For instance, X-rays were historically (and are currently) used as an imaging technique; the discovery of their oncolytic capability led to their employ in radiotherapy (ablation of malignant tumours).
Side effect
Adverse effect
Toxicity
Side Effect
Idiosyncrasy
Noxious stimulus
Drug interaction
Acute toxicity