OBJECTIVES: This study determined the frequency of OTC medication use following treatment guidelines, specifically the percentage of patient visits recorded in the National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Medical Care Survey outpatient department (NHAMCS) that included (1) bisphosphonates with calcium, (2) divalproex or carbamazepine therapy with folic acid, and (3) fentanyl or methadone therapy with a laxative.  METHODS: A retrospective, observational study was conducted using NAMCS and NHAMCS data from 2006-2008. Data for visits including bisphosphonates with calcium, divalproex or carbamazepine in women of childbearing age with folic acid, and methadone or fentanyl in adults over age 40 years with laxatives were collected.  Descriptive statistics and logistic regression were used to analyze weighted data to produce national estimates. RESULTS: Calcium was used in 25.3% of visits with bisphosphonate therapy; visits associated with antiepileptics and chronic opioids had lower rates of supplementation, with 5.0% including folic acid and 3.7% including laxatives. Visits by Asians (OR=2.74;CI 1.42-5.27) and patients from the northeast (OR=1.57; CI 1.10-2.24) or midwest (OR=1.65;CI 1.15-2.37) were more likely to include calcium, while visits by patients with Medicaid (OR=0.48;CI 0.30-.0.78) were least likely to include calcium. In visits with antiepileptics, Asian women (46.0%) and women with private insurance (9.5%) were more likely to receive folic acid. In visits that included chronic opioids, only 1.2% of patients age 40-49 years included a laxative while 6.7% of visits by patients over 70 years included a laxative. Laxative use was low in visits by African American patients (1.8%) and patients residing in a zip code with <12.84% of the population holding a bachelor’s degree (1.9%). CONCLUSIONS: The majority of patients were not receiving OTC supplementation vital to the treatment of osteoporosis, epilepsy, and chronic pain. Targeted intervention to improve treatment guideline adherence would increase compliance with recommendations.