Congruence and celebrity endorser credibility in Japanese OTC drug advertising

Purpose: Based on congruency theory, this study aims to examine the effects of celebrity endorsement on endorser credibility in Japanese over-the-counter (OTC) drug advertising using multiple celebrity categories. In particular, this research explored brand–endorser congruence and endorser–consumer congruence and their roles in attitude formation. Design/methodology/approach: A 3 (endorser categories: actor/actress, athlete and talent/TV personality) × 2 (endorser’s gender) factorial experimental design with 480 Japanese consumers was used in the study. Findings: In Japanese OTC drug advertising, actors/actresses and athletes were regarded as more credible than talents (TV personalities) by Japanese consumers. Endorser categories also had a significant influence on identification with the endorser through ideal self-congruency. Additionally, endorser credibility mediated the relationship between identification and advertising evaluations. However, it did not mediate the relationship between perceived similarity with the endorser and advertising responses. Originality/value: Little is known about the effectiveness of celebrity endorsers in OTC drug advertising from a source credibility perspective. This study attempted to shed light on the role of endorser fit in the framework of source credibility in drug advertising that usually places an emphasis on informational cues rather than peripheral cues such as source effects.