Health literacy, representing the ability to understand and apply health information, is a key determinant of public health. In Eastern Europe, decades of underinvestment in health education, socioeconomic disparities, and institutional mistrust have contributed to persistently low levels of health literacy. Objective: This review synthesizes evidence on the social consequences of inadequate health literacy in Eastern Europe, focusing on behavioral, structural, and policy-related outcomes. Methods: A narrative literature review was conducted using PubMed, Scopus, Web of Science, Google Scholar and institutional reports. Studies were included if they examined health literacy, public medical education, and social outcomes in Eastern European populations. Results: The synthesis of evidence identified four major thematic domains through which inadequate health literacy is associated with negative outcomes in Eastern European populations. Low health literacy is consistently associated with preventable disease, poor health behaviors, limited uptake of preventive services, and reduced adherence to medical advice. Vulnerable groups bear a disproportionate burden. Inadequate health knowledge is also associated with increased and inappropriate healthcare utilization, delayed care-seeking, and higher rates of avoidable mortality. Furthermore, low health literacy is plausibly linked to the proliferation of health misinformation, erosion of trust in healthcare systems, and has contributed to excess mortality during public health crises such as the COVID-19 pandemic. Discussion: The observed patterns are shaped by historical and structural factors, including the postcommunist legacy of under-resourced health systems and the persistent under-prioritization of preventive care. Eastern Europe is a heterogeneous region, and the availability of health literacy data varies considerably across countries, limiting the generalizability of findings. At the clinical level, healthcare providers play a key role in identifying low health literacy, adapting communication strategies, and addressing vaccine hesitancy and misinformation. Addressing these challenges requires coordinated strategies, investment in education, culturally tailored communication, and cross-sectoral collaboration. Improving public health literacy can enhance health outcomes, reduce system costs, and strengthen societal resilience. Conclusions: This review underscores the challenges associated with health literacy in Eastern Europe, illustrating how insufficient health literacy contributes to detrimental behaviors, undermines trust in healthcare systems, exacerbates misinformation, and ultimately imposes a significant societal and systemic burden on public health.