We explored the association between understanding a proper use of over-the-counter cold medicines and a choice of information source to purchase such medicines. We conducted an internet survey in March 2011 regarding false perceptions about cold medicines as well as understanding of package inserts. Respondents (20〜69 years old) to the main survey were individuals who purchased cold medicines based on TV commercials (CM group) and those who purchased these medications in consultation with pharmacists (consultation group). We surveyed 121 and 159 respondents in the CM and consultation groups, respectively. We calculated the principal component scores for false perceptions of cold medicines and the respondents’ understanding of the package inserts. The median scores were 0.20 (CM group) and -0.08 (consultation group) false perceptions, and -0.18 (CM group) and 0.15 (consultation group) for understanding. The Mann-Whitney U-test revealed that the CM group had more misconceptions regarding cold medicines compared with the consultation group (P<0.001). Furthermore, the consultation group acquired greater understanding of the package inserts than the reference CM group (P＝0.005). These results suggest an association between understanding the proper use of over-the-counter cold medicines and choice sources of information on purchasing these medicines. They further suggest that a lack of knowledge or understanding of cold medicines does not lead to consultations with a pharmacist about the purchase.