Primum non nocere

Primum non nocere is a Latin phrase that means "first, do no harm." The phrase is sometimes recorded as primum nil nocere.

Non-maleficence, which is derived from the maxim, is one of the principal precepts of bioethics that all healthcare students are taught in school and is a fundamental principle throughout the world. Another way to state it is that, "given an existing problem, it may be better not to do something, or even to do nothing, than to risk causing more harm than good." It reminds the health care provider that they must consider the possible harm that any intervention might do. It is invoked when debating the use of an intervention that carries an obvious risk of harm but a less certain chance of benefit.

Non-maleficence is often contrasted with its corollary, beneficence.

The origin of the phrase is uncertain. The Hippocratic Oath includes the promise "to abstain from doing harm" (Greek: ἐπὶ δηλήσει δὲ καὶ ἀδικίῃ εἴρξειν) but does not include the precise phrase. Perhaps the closest approximation in the Hippocratic Corpus is in Epidemics: "The physician must ... have two special objects in view with regard to disease, namely, to do good or to do no harm" (book I, sect. 11, trans. Adams, Greek: ἀσκέειν, περὶ τὰ νουσήματα, δύο, ὠφελέειν, ἢ μὴ βλάπτειν).

According to Gonzalo Herranz, Professor of Medical Ethics at the University of Navarre, Primum non nocere was introduced into American and British medical culture by Worthington Hooker in his 1847 book Physician and Patient. Hooker attributed it to the Parisian pathologist and clinician Auguste François Chomel (1788–1858), the successor of Laennec in the chair of medical pathology, and the preceptor of Pierre Louis. Apparently, the axiom was part of Chomel's oral teaching.

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