Health literacy is the ability to access, understand, appraise and use health information and health services in ways that promote and maintain health and wellbeing. The modern concept extends considerably beyond simply being able to read a leaflet or understand medical vocabulary. WHO describes health literacy as involving personal knowledge and competencies developed through everyday activities and social interactions, while emphasising that these abilities are mediated by organisational structures and the availability of resources.
Health literacy therefore includes the interaction between individuals and the systems providing information and care. A person can have strong general education yet struggle with a complex medical system, just as someone with limited formal education can have highly developed practical knowledge in a particular health context.
Functional health literacy involves practical abilities such as reading prescription instructions, understanding appointment information, recognising symptoms, following dosage directions and completing health forms. Interactive health literacy involves communicating with healthcare professionals, asking questions, explaining symptoms and participating in decisions. Critical health literacy involves evaluating evidence, recognising uncertainty, identifying misleading claims and understanding how social, commercial and political factors influence health information. Digital health literacy extends these skills to online environments, requiring people to search, interpret, compare and assess digital sources. These dimensions overlap, and a person may be competent in one while finding another difficult. Consequently, health literacy is better viewed as a multidimensional capability than as a simple measure of intelligence or reading ability.
Health literacy affects how people navigate healthcare systems. Someone with good health literacy can more readily identify what information they need, understand what a diagnosis means, compare treatment options, recognise when professional help is required and communicate relevant information to clinicians. Poor health literacy can contribute to misunderstanding medication instructions, difficulty navigating appointments, confusion about risk, delayed care and difficulty distinguishing reliable evidence from unsupported claims. However, responsibility does not rest entirely with individuals. WHO explicitly describes organisational health literacy and stresses that health services and information providers should make trustworthy information understandable, accessible and actionable. Health literacy is therefore partly an individual capability and partly a property of the environments in which people make health decisions.
Health literacy is closely connected with numeracy and risk communication. Medical information frequently involves percentages, probabilities, relative risks, screening test accuracy and uncertainty. Understanding that a treatment reduces relative risk by 50 percent is difficult without knowing the baseline risk, because the absolute benefit could be large or small depending on the starting probability. Similarly, a positive screening result does not necessarily mean that someone has the disease because predictive values depend on prevalence and test characteristics. Health-literate communication therefore uses absolute frequencies, natural frequencies and clear time frames where appropriate. Visual aids and plain language can make complex evidence more understandable without oversimplifying it.
Digital health literacy has become especially important because health information is now encountered through search engines, social media, videos, forums, online advertising, messaging applications and increasingly AI tools. The volume of available information can create the impression that accessibility equals reliability, but online material varies enormously in accuracy, currency, evidence and commercial motivation. WHO advises people to consider who produced information, when it was produced, how the claims are supported and whether the source is reliable. NHS resources similarly emphasise that online health information is not uniformly trustworthy or up to date. Health literacy therefore includes the ability to pause, verify claims and seek professional advice when online information concerns diagnosis or treatment.
Health literacy should not be confused with simply knowing many medical facts. A highly knowledgeable person can still misunderstand a particular statistic, be vulnerable to confirmation bias or struggle to apply general information to their own circumstances. Conversely, a person may have limited medical vocabulary but successfully make appropriate decisions when information is presented clearly and support is available.
Health literacy is also context-dependent: people may understand a familiar chronic condition but struggle when confronted with an unfamiliar diagnosis or emergency. Stress, pain, fear, fatigue, language barriers, disability and cognitive load can reduce comprehension and decision-making capacity in practice. Effective health communication therefore needs to accommodate the circumstances in which information is received.
Improving health literacy involves both individual and system-level measures. Individuals can learn to identify credible sources, ask clinicians for clarification, compare information from independent authoritative sources and check whether claims are supported by appropriate evidence. Healthcare organisations can use plain language, accessible formats, clear navigation, interpreters, decision aids and communication techniques such as asking patients to explain information back in their own words.
WHO emphasises equitable access to quality education and trustworthy information and argues that health literacy is shaped by wider social conditions rather than being solely an individual's responsibility. This perspective matters because simply telling people to become better consumers of information does not address inaccessible services, confusing terminology or poorly designed information environments.
Health literacy is ultimately important because health decisions frequently involve uncertainty, competing options and potentially serious consequences. A health-literate person is better positioned to understand what is known, what is uncertain, what an intervention can realistically achieve and when professional assessment is necessary. It supports informed consent, medication safety, preventive behaviour, appropriate use of healthcare and resistance to misinformation.
NHS England's shared-decision-making framework explicitly recognises that people with lower health literacy may require additional support to participate actively in healthcare decisions. Health literacy should therefore be understood not as a test of whether an individual is sufficiently educated, but as a shared responsibility involving people, clinicians, organisations, governments, educators and information providers.
