OBJECTIVES: Little is known about how the public uses the nicotine patch after it was reclassified from prescription to over-the-counter (OTC) status. This observational study describes the characteristics of consumers who purchase OTC nicotine patches from pharmacies and to determine factors associated with off-label use of nicotine patch. METHODS: Prospective, longitudinal study of N=600 OTC nicotine patch consumers from a random sample of 30 retail pharmacies throughout San Diego County. Each subject completed a self-administered, anonymous questionnaire at the time of purchase and at 2-weeks after using the patch. Off-label use was defined as intention to smoke while on the patch or using the patch for harm reduction rather than quitting. Logistic regression was performed to determine the factors associated with off-label use. RESULTS: The cohort had low Fagerstrom nicotine dependence score (mean=3.58). Sixty-four percent stated that their physicians were not aware of them using the patch. Main reasons prompting purchase included self-initiative (54%), family/friends (20%), physician advice (15%), and pharmacist's advice (3%). Eight percent intend to use the patch for harm reduction rather than quitting. Minorities and individuals with high income were more likely to engage in off-label use. Of those who returned the second questionnaire (N=155), 78% did not review the self-aid counseling materials enclosed in the product package. Forty-five percent reported smoking cigarettes at 2 weeks, and 8% admitted to using more than one patch per day. CONCLUSION: A substantial number of the consumers had low Fagerstrom nicotine dependence scores and would not have qualified as for the patch under the prescription setting. Most consumers did not review the self-aid materials even though it was included in the package, and some consumers intentionally engaged in off-label use of the product. Further research is needed to devise interventions to ensure proper usage of OTC nicotine patch by the public.