In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequences of the use of a drug.
Occasionally, drugs are prescribed or procedures performed specifically for their side effects; in that case, said side effect ceases to be a side effect, and is now an intended effect. 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).
Use of drugs for unapproved indications—that is, for their side effects—is termed off-label use. For instance, opioids, which are approved as palliative treatment for pain, may also be used for their euphoriant properties as anxiolytics or antidepressants, whether medically or recreationally.
Off-label use of drugs, although similar in meaning to side effects, is not to be confused with them; side effects describe the mechanism of action that a drug used off-label takes, whereas off-label use implies the desired consequences of using a drug for its side-effects.
Off-label use of drugs is legal; the manner in which prescription medication is to be used is solely at the discretion of the prescriber. However, the marketing of drugs towards unapproved indications is illegal; in fact, several pharmaceutical development firms have been fined for unapproved promotion of their products.
Read more about Side Effect: Examples of Therapeutic Side-effects
Famous quotes containing the words side and/or effect:
“I come more and more to the conclusion that one must take the side of the minority which is always the more intelligent one.”
—Johann Wolfgang Von Goethe (1749–1832)
“Because just as arms have no force outside if there is no counsel within a house, study is vain and counsel useless that is not put to virtuous effect when the time calls.”
—François Rabelais (1494–1553)