BACKGROUND:Irrational use of antibiotics is prevalent worldwide. But our understanding on consumer behaviors in the use of antibiotics is very limited. This study aims to identify consumer behavior patterns in the use of antibiotics for upper respiratory tract infections (URTIs). METHODS:The study will employ a mixed methods approach based on the "Capacity & Opportunity & Motivation - Behavior" (COM-B) framework. The COM-B attributes of consumers in relation to the use of antibiotics will be extracted from a systematic literature review. Semi-structured in-depth interviews will be conducted on 20-25 community residents with URTI symptoms over the past three months to illustrate the meaning and implications of the thematic categories of COM-B attributes for the purpose of measurement development. The measurement instruments will be modified and validated through Delphi consultations with 15 experts and a survey of 300 adult residents in Wuhan. A cross-sectional survey using the finalised measurement instruments will be conducted on 2700 adult residents randomly selected from 18 residential communities across 9 municipalities in 3 provinces in China. Multi-level latent class analyses will be performed to categeorise the respondents based on the indicators measuring the behavioral features (need recognition, information searching, alternative assessment, purchase, use, and post-use evaluation) of consumers in purchasing, consuming and disposing antibiotics for URTIs. Multi-nominal regression analyses will be performed to determine the predictors of different behavior patterns. DISCUSSION:This study aims to classify consumers into distinguished categories of behavior patterns toward the use of antibiotics for URTIs. Such a classification system categories the consumers with similar behavior features into the same group so that better targeted interventions can be developed. The COM-B model adopted in this study can also help us better understand the underlying mechanisms of different behavior patterns of consumers.