In this study, we investigated the status of researching drug information online, and the type of Internet user who uses anonymous Web communities and websites. A Web-based cross-sectional survey of 10875 male and female Internet users aged 16 and over was conducted in March 2010. Of 10282 analyzed respondents, excluding medical professionals, about 47% reported that they had previously searched the Internet for drug information and had used online resources ranging from drug information search engines and pharmaceutical industry websites to social networking sites and Twitter. Respondents who had researched drug information online (n=4861) were analyzed by two multivariable logistic regressions. In Model 1, the use of anonymous websites associated with age (OR, 0.778; 95% CI, 0.742-0.816), referring to the reputation and the narrative of other Internet users on shopping (OR, 1.640; 95% CI, 1.450-1.855), taking a prescription drug (OR, 0.806; 95% CI, 0.705-0.922), and frequent consulting with non-professionals about medical care and health (OR, 1.613; 95% CI, 1.396-1.865). In Model 2, use of only anonymous websites was associated with age (OR, 0.753; 95% CI, 0.705-0.805), using the Internet daily (OR, 0.611; 95% CI, 0.462-0.808), taking a prescription drug (OR, 0.614; 95% CI, 0.505-0.747), and experience a side effect (OR, 0.526; 95% CI, 0.421-0.658). The analysis revealed the profiles of Internet users who researched drug information on social media sites where the information providers are anonymous and do not necessarily have adequate knowledge of medicine and online information literacy.