Background <p>Social inequalities in health care remain a pressing issue with direct consequences for treatment outcomes. One complex mechanism contributing to this inequality involves patient’s health literacy – including their ability to perceive a medical need and understand the availability of care. This scoping review aims to examine whether economically disadvantaged groups are at greater risk of low health literacy and to identify potential intervention targets to improve health care access and equity.</p> Methods <p>We systematically searched MEDLINE (Ovid) in May 2022 and again in November 2024 for peer-reviewed original studies (English/German; 2000–2024) from high-income countries that compared lower- versus higher-income groups on health literacy.</p> Results <p>Drawing on 179 peer-reviewed original research articles, the review found, in most cases, a consistent association between low income and limited health literacy, including general health literacy, mental health literacy, disease-specific knowledge (e.g., cancer, oral health), and eHealth literacy. Notably, individuals with chronic illnesses may possess greater condition-specific knowledge than the general population, regardless of income. However, inconsistent income classifications together with variation in the health-literacy constructs used undermine comparability.</p> Conclusions <p>In summary, the results suggest that efforts to improve population health literacy must consider the circumstances of people living in poverty and develop strategies to reach them. Future research should explore additional social determinants of health literacy – such as education, occupation, or early-life adversity – using longitudinal approaches to better understand causal pathways.</p> Trial registration <p>PROSPERO 2022 CRD42022334775.</p>