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 effect, side and/or effect:
“What is done for science must also be done for art: accepting undesirable side effects for the sake of the main goal, and moreover diminishing their importance by making this main goal more magnificent. For one should reform forward, not backward: social illnesses, revolutions, are evolutions inhibited by a conserving stupidity.”
—Robert Musil (1880–1942)
“And so all the night-tide, I lie down by the side
Of my darling, my darling, my life and my bride
In her sepulchre there by the sea—
In her tomb by the side of the sea.”
—Edgar Allan Poe (1809–1849)
“To speak impartially, the best men that I know are not serene, a world in themselves. For the most part, they dwell in forms, and flatter and study effect only more finely than the rest.”
—Henry David Thoreau (1817–1862)