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How does the principle of nonmaleficence apply to medical treatment?

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Marble portrait bust of Hippocrates atop a tall rectangular base inscribed with an epigram in Greek, displayed against a black background. — Bioethics A Roman bust of Hippocrates, copied from a Greek original, c. 3rd century bce; in the collection of the Antichità di Ostia, Italy.

In the context of bioethics, the principle of nonmaleficence requires that health care professionals "do no harm" to their patients. This concept is rooted in the traditional Latin phrase primum non nocere ("first, do no harm").12

In medical practice, nonmaleficence serves as a fundamental moral condition guiding professional behavior. It functions alongside other core principles, such as autonomy, beneficence, and justice, to form a framework for addressing ethical issues in medicine.13

Applying this principle can be complex, particularly when medical interventions involve difficult trade-offs. For example, while physicians are obligated to avoid harm, modern medical advancements—such as mechanical ventilators or life-sustaining treatments—can create ambiguity regarding whether continuing or withdrawing such support constitutes "harm" in cases of terminal illness or permanent unconsciousness. Furthermore, nonmaleficence may conflict with other principles, such as autonomy, when a patient refuses life-saving treatment. Ultimately, the principle emphasizes the ethical necessity for practitioners to exercise sound professional judgment and act in good faith to protect the patient's well-being.31