Background
Speaking up among healthcare professionals plays an essential role in improving patient safety and quality of care, yet it remains complex and multifaceted behaviour. Despite awareness of potential risks and adverse outcomes for patients, professionals often hesitate to voice concerns due to various influencing factors. This complexity has encouraged research into the determinants of speaking-up behaviour in hospital settings. This review synthesises these factors into a multi-layered framework. It aims to provide a more comprehensive perspective on the influencing factors, which provides guidance for interventions aimed at fostering environments contributing to speaking up in hospitals.

Methods
A systematic review was conducted in November 2024, searching databases: PubMed, Scopus and Web of Science. Following PRISMA guidelines and the three stages for thematic synthesis, we developed the classification of influencing factors. Out of 1,735 articles identified articles, 413 duplicates were removed, 1,322 titles and abstracts were screened, and 152 full texts (plus six additional articles) were assessed. Ultimately, 45 articles met the inclusion criteria.

Results
The review categorised influencing factors into four categories: individual (29 articles, 64%), relational (21 articles, 47%), contextual (19 articles, 42%), and organisational (26 articles, 58%). These categories encompass motivating, hindering and trade-off factors affecting speaking up among healthcare professionals in hospitals.

Conclusions
The multi-layered framework highlights the dynamic interplay of factors influencing speaking up among healthcare professionals. A systems approach is essential for identifying barriers and enablers and designing effective speaking up interventions. This framework serves as a foundation for more focused research and practical guidance, enabling healthcare leaders to address barriers across all categories. By fostering environments that support open communication, organisations can enhance patient safety and quality of care.@en