OBJECTIVES: To understand how patient responses to FDA safety warnings differ by provider type, geography, disease burden, race and socio-economic status (SES) for a nationally representative sample of Medicare beneficiaries.. METHODS: We identified 11 widely prescribed chronic medications that received black box warnings (BBW) between 2006-2009.  We examined the demand response to the warnings and the extent to which patient, provider and area characteristics affected rates of discontinuation.  Multivariate analyses controlled for baseline (pre-alert) rates of medication adherence, as well as a rich set of demographic and area characteristics.  RESULTS: Response to a black box warning varied substantially across products.  Medications prescribed by a specialist were more likely to be discontinued (OR=1.047, p<0.01), as were medications prescribed to beneficiaries in the Northeast (ORs= 1.37-1.70, p<0.001). Beneficiaries eligible for low-income subsidies or dual-eligible (Medicaid and Medicare) were less likely (ORs=0.911 and 0.915, p<0.01, respectively) to discontinue use after a BBW.  While Whites and Blacks had similar responses to a safety alert, they were more likely to discontinue use than Hispanics and Asians (ORs=0.827 and 0.876, respectively, p<0.001).  CONCLUSIONS:  Substantial variation in response to FDA-issued safety alerts suggest that BBW content is not reaching all clinician and patients, particularly those of lower socioeconomic status.  New approaches are needed to influence patient-clinician deliberation about the risks and benefits of available agents when a black box warning is issued.  Increased efforts are needed to inform physicians, low-educated patients, as well as low-SES and minority patients, of safety warnings.