Definitions of health literacy have evolved from notions of health-related literacy to a multidimensional concept that incorporates the importance of social and cultural knowledge, practices and contexts. This evolution is evident in the development of instruments that seek to measure health literacy in different ways. Health literacy measurement is important for global health because diverse stakeholders, including the WHO, use these data to inform health practice and policy, and to understand sources of inequity. In this Practice paper, we explore the potential for negative consequences, bias and epistemic injustice to occur when health literacy instruments are used across settings without due regard for the lived experiences of people in various contexts from whom data are collected. A health literacy measurement approach that is emic-sensitive, strengths based and solution oriented is needed to minimise biased data interpretation and use and to avoid epistemic injustice.