Early participatory design (PD) projects tended to be of limited size and complexity. Over the last two decades, however, various attempts have been made to apply PD to large-scale information technology projects. Although studies have suggested that scaling the methodology to fit larger and more complex projects can be problematic, no attempts have been made to form a comprehensive overview of the associated challenges. To remedy this situation, a systematic literature review of relevant studies was conducted. From an initial 780 references retrieved from databases, 17 articles met the predefined criteria and were included in the review. The review resulted in the extraction of seven categories of challenges. A discussion of the identified challenges as a potential threat to the methodology's integrity is provided. The review offers a multifaceted understanding of the challenges related to the scaling of PD, which, given their nature, risk compromising core PD principles.