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 medical ethics that all medical students are taught in medical school and is a fundamental principle for emergency medical services around 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 physician and other health care providers 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.