Countless studies have demonstrated that many emergency-room visits and hospital admissions are drug-related and that a significant proportion of these drug-related visits (DRVs) are preventable. It has not been previously studied which DRVs could be prevented through enhanced monitoring of therapy. The objective of the study was to determine the incidence of DRVs attributed to laboratory or physiologic abnormalities. Three authors independently performed comprehensive searches in relevant health care databases using pre-determined search terms. Articles discussing DRV associated with poisoning, substance abuse, or studied among existing in-patient populations were excluded. Study country, year, sample, design, duration, DRV identification method, proportion of DRVs associated with laboratory or physiologic abnormalities and associated medications were extracted. The three authors independently assessed selected relevant articles according to the Strengthening the reporting of observational studies in epidemiology (STROBE) as applicable according to the studies' methodology. The initial literature search yielded a total of 1,524 articles of which 30 articles meeting inclusion criteria and reporting sufficient laboratory or physiologic data were included in the overall analysis. Half employed prospective methodologies, which included both chart review and patient interview; however, the overwhelming majority of identified studies assessed only adverse drug reactions (ADRs) as a drug-related cause for DRV. The mean (range) prevalence of DRVs found in all studies was 15.4% (0.44%–66.7%) of which an association with laboratory or physiologic abnormalities could be attributed to a mean (range) of 29.4% (4.3%–78.1%) of cases. Most laboratory-associated DRVs could be linked to immunosuppressant, antineoplastic, anticoagulant and diabetes therapy, while physiologic-associated DRVs were attributed to cardiovascular therapies and NSAIDs. Significant proportions of laboratory and physiologic abnormalities contribute to DRVs and are consistently linked to specific drugs. These therapies are potential targets for enhanced medication monitoring initiatives to proactively avert potential DRVs.