Background: The use of acupuncture to treat dysfunction and disease and its integration into western medicine continues, as the scientific basis of acupuncture is becoming better understood. While acupuncture is considered a safe therapeutic intervention when given by appropriately trained practitioners, adverse reactions can occur even in the hands of an experienced acupuncturist. There has been little attempt to standardize nomenclature or to classify adverse reactions to acupuncture (ARAs). Objectives: To review the physiological effects of acupuncture and their contribution to commonly reported ARA and to propose a conceptual framework for ARAs according to their likely neurophysiological mechanisms. Major findings: A three-tiered framework for the classification of ARAs is presented in line with current definitions of drug adverse reactions. Many ARAs reported in the current literature fit with the first and second levels of the framework. This clearly demonstrates an important safety distinction between an ARA and negative outcomes due to practitioner error. The third level of ARA, type A or type B can be used to categorize the majority of ARAs. Conclusion: The classification of ARAs based on their neurophysiology may lead to clearer definitions, improved terminology usage, ARA identification, and reporting if adopted by clinicians. A western conceptual framework is proposed for the classification of common ARAs in keeping with the codifications established with drug adverse reaction reporting.