Educational Content: This article is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.
Definition of Nocebo
Medically reviewed by Dr. Otari Nergadze, Neurosurgeon | Updated: January 2026
Nocebo: A negative placebo effect as, for example, when patients taking medications experience adverse side effects unrelated to the specific pharmacological action of the drug. The nocebo effect is associated with the person's prior expectations of adverse effects from treatment as well as with conditioning in which the person learns from prior experiences to associate a medication with certain somatic symptoms.
Nocebo comes from the Latin noceo, to harm and means "I shall harm" whereas placebo means "I shall please."