Health Literacy & Plain Language

Health information is often read at the worst possible moment: after a diagnosis, while waiting for a result, or while looking after someone who is ill. A 2003 review by Roy Kessels in the Journal of the Royal Society of Medicine states that 40 to 80 per cent of the medical information practitioners give is forgotten immediately, and that almost half of what is remembered is incorrect. The review does not tie that sentence to one study, so it is a broad indication, not a measured rate. For anyone designing screens, letters or messages in health, the words on the page are part of the care.

What health literacy means

Health literacy is the ability to find, understand and use health information and services to make decisions. The United States Healthy People 2030 programme separates two ideas. Personal health literacy is how well an individual can do this. Organisational health literacy is how well an organisation makes it possible for people to do this. Under that framing, the burden does not sit only with the reader: a confusing form or portal is a gap on the organisation's side. The NHS standard for creating health content asks organisations for plain English and a documented clinical review process.

Difficulty is common. The CDC notes that even skilled readers struggle when medical terms or how the body works are unfamiliar. The NHS digital service manual states that more than 4 in 10 adults struggle with general health content, and more than 6 in 10 when the content includes numbers and statistics, although that page gives no source or year for the figures. The figures match a 2015 study by Rowlands and colleagues in the British Journal of General Practice, which found 43 per cent of a sample of English working-age adults below a health-literacy threshold for understanding everyday health materials, rising to 61 per cent when the materials also required numeracy - the NHS page does not name this study, so the match is not confirmed as its source. In Australia, the Australian Bureau of Statistics ran a Health Literacy Survey in 2018 with 5,790 adults. Of those, 33 per cent said it was always easy to engage with healthcare providers and 56 per cent said it was usually easy. These are self-reported answers, not tests of understanding.

Why stress changes what people take in

In the Kessels review, stress can narrow attention to the main message, such as the diagnosis, so instructions about medicines or follow-up are not stored. In a group of outpatients described in the review, moderate anxiety helped recall while very high or very low anxiety hindered it. Specific instructions were remembered better than general ones, and simple wording better than complex wording. The review concludes that spoken information should be backed by written or visual material. For design, this points to putting the key instruction first and being specific.

Writing techniques that lower the effort

• Short sentences and paragraphs. The NHS digital service manual sets up to 20 words per sentence and up to 3 sentences per paragraph, and a reading age of 9 to 11 for most content.
• Plain terms first. Where a medical term is needed, the NHS approach is to give the everyday word first and the technical term in brackets.
• Active voice and present tense. Digital.gov's plain language guide explains that active voice shows who does what, and that hidden verbs make sentences longer.
• Specific amounts. The NHS guide prefers exact quantities to vague phrases such as a long time.
• Test with real readers. The NHS health literacy page says readability tools can flag long sentences or passive voice, but they cannot show whether content is usable. The CDC Clear Communication Index is a scoring tool of 20 items for checking public health material.

Checking understanding: teach-back

Teach-back is a method in which a person explains what they have been told in their own words, and the explainer clears up any gaps and checks again. A 2020 systematic review in PLOS ONE (Talevski and colleagues) found it effective in 19 of 20 included studies, across outcomes such as knowledge recall and hospital readmissions. The quality of those studies varied: four were rated high, nine moderate and seven weak, so the evidence is encouraging but uneven. In a digital product, it can appear as a short recap step.

Numbers and results

Numbers add a second layer of difficulty. A review of numerical risk communication (Brust-Renck, Royer and Reyna) argues that people rely on the gist of a figure, such as whether a risk is low or high, and that displays should make that meaning easy to see. It points to frequencies, icon arrays and charts that keep the denominator visible. A 2024 systematic review in JMIR of 18 studies on laboratory results found that horizontal bars with coloured blocks scored highest for satisfaction and usability. A reference range and short explanations of what a result means added to understanding.

Two illustrative rewrites

Medicine instruction. Before: 'One tablet PO BID with food. Avoid concomitant analgesics without pharmacist advice.' After: 'Take 1 tablet in the morning and 1 tablet in the evening, with food. Ask your pharmacist before taking any other painkiller with this medicine.' It replaces abbreviations with times of day and names who to ask.

Lab result. Before: 'Value outside reference interval.' After: 'Your result is higher than the usual range. The usual range is 4 to 6, and your result is 7. Your care team will explain what this means for you.' It gives the number, the range and a next step, and does not guess at a meaning.

Related Showcase cards

• Write to a reading age - a rewrite of dense appointment-prep text against GOV.UK's plain-language limits.
• Write the dose the patient reads, not the dose the chart stores - the same idea applied to medication instructions.