Clear instructions
An instruction works when its reader can tell what to do, who does it, whether it is required and in what order, and can act on it with what the reader can observe. Writing one means stating the action and its force, wording any condition so that it cannot be misread, keeping the instructions apart from the explanation around them, and testing what readers understand. Writing a standard operating procedure is covered in standard operating procedures, testing a leaflet with the people who rely on it in testing with real readers, and the pictures that go beside each step in visual aids for patients.
State the action and its force
The advice on who acts, on direct wording and on separating and testing instructions comes from the Plain English Campaign's chapter on writing in plain English in a 2007 book. An instruction should make the action, the person who acts and the sequence easy to identify. A passive statement can leave readers unsure whether they, their doctor or someone else should act, and addressing the reader directly helps prevent that ambiguity. The 2007 book reaches the record as an incomplete copy, with internal pages missing, whose conversion has had no full page-by-page proofread.
Patient leaflets show what the alternative costs. A 2015 journal article that assessed leaflets taken from household medicine cabinets found one of the most important sentences of a paracetamol leaflet written in the impersonal passive — that immediate medical advice should be sought in the event of an overdose — where "get immediate medical advice if…" states who must act. A second leaflet warned that its tablets can cause dizziness and then ran on into the precaution; split in two, it becomes a statement and then an instruction naming the condition and the action: if you feel dizzy, do not drive or operate machinery. The same leaflet told readers to take their medicine in its original packaging with them in order to enable the doctor to identify their medication easily, which is more crisply put as carrying the medicine so that the doctor knows exactly what it is. The leaflet assessment, the usage column and the NICE article below come from three issues of EMWA's journal Medical Writing, March 2015 (volume 24, number 1, Plain Language and Readability), December 2012 (volume 21, number 4, Obesity and Type 2 Diabetes) and September 2013 (volume 22, number 3, Health Economics and Market Access), each copied without content repair from a Markdown conversion that breaks ligatures, mangles multi-column tables, interleaves page headers and footers, and represents figure text as marked text.
The same article found a related failure: leaflets that expect readers to notice what they cannot observe. The second leaflet listed decreased volume within blood vessels among the symptoms of an overdose and told readers to tell their doctor if they noticed low blood magnesium and sodium levels, and the paracetamol leaflet told them to inform their doctor if they noticed a severe reduction in the number of white blood cells. An instruction should name an action the reader can take on evidence the reader can have.
An instruction should distinguish a requirement from a suggestion or optional help, because polite conditional language can make an essential action sound optional. The Plain English Campaign recommends giving instructions directly, and keeping "please", which softens the tone, for an instruction that would be helpful rather than one that must be done.
The guidance programmes of the National Institute for Health and Care Excellence (NICE) differed in 2013 in the style of their recommendations and in their standard forms of wording, but every programme wrote to the same general principles of effective writing. For every recommendation, make clear what the patient group or target population is and exactly what the professionals need to do. Start with the action if possible, and include only one action per recommendation or bullet point. Be specific: if other treatments should be tried first, state how many and for how long. Use "and" and "or" in lists of criteria so that it is clear whether all or only some have to be met, or else introduce the list with a phrase such as "if all of the following criteria are met", which is useful where the list is long or where certain criteria have to be met. Leave out background information and commentary. Make every word count, and make the recommendation a direct instruction where possible, particularly where it is aimed directly at healthcare professionals.
Where NICE guidance puts the evidence and the committee's reasoning behind its recommendations is set out in health technology guidance.
A 2010 journal guide to writing in plain language applies the same rule to instructions: be specific rather than assume that readers know what to do, writing "Walk for 10 minutes 3 times each day" rather than "Exercise moderately". The 2010 issue of the AMWA Journal (volume 25, number 4) that carries the guide reached the record through a layout-aware Poppler XML conversion copied without content repair, in which figure labels can run into the prose and cover and contents columns can interleave.
Word the condition so it cannot be misread
The advice on "in case" comes from a 2012 journal column on English grammar and style. "In case" implies that a contingency plan is being made, as in "I will take an umbrella with me in case it rains" or "We will drive on the main road in case there is flooding on the minor roads". It seems to be used with increasing frequency as shorthand for "if it is the case that", which is not correct English and can mislead. Signs engraved beside the lift call buttons on every floor of a conference hotel read "Do not use elevator in case of fire", which, read as written, says not to use the lift in case there is a fire inside it or in case being in it might cause one. "If there is a fire, do not use the elevator" is more fluent, and "If there is a fire, use the stairs" better still.
The same construction turns up in study documentation, as in "In case of special patient groups (children, patients with dementia, etc.) describe the procedure for obtaining informed consent", where what is meant is "If the study population is a special patient group …". The hotel signs may be a lost cause, being far too common ever to be corrected, but writers should still watch for the construction in their own documents, where an "If …" sentence often offers the best solution: it may be slightly longer, but the shortest solution is not always the best, even though brevity should always be the aim.
The 2010 guide also advises avoiding conditional "if… then" sentences as much as possible, even though health information is often qualified and may change, because most readers find them much more difficult to comprehend. That objection is a different one from the objection to "in case" above.
Separate instructions from explanation
Requested actions should stay visible: direct instructions should be kept separate from general information so that they do not get lost, and where explanations are needed and there are several instructions, a clear checklist can serve as a reminder. Steps go in the order they need to happen, and that order should be as clear to the reader as it is to the writer. A standard letter designed to cover many possibilities makes it difficult for an individual reader to see which information refers to them.
The rewrite of an emergency instruction issued during Hurricane Katrina is set out in visual aids for patients. Its heading for shutting off gas and electricity opens "Prevent fire!", and its list for a smell of gas also tells the reader to turn off the main gas valve.
Test what readers understand
Where the writer is not sure the instructions are clear, a colleague or, better still, someone outside the writer's field can read them and explain back what they would do, and any difficulty they have shows that the instructions may need revising.
In a 2025 symposium talk, a patient who uses an insulin pump and a continuous glucose monitor said that the instructions and literature patients receive may not be patient friendly even after many rounds of review, and may need adapting to different learning needs or to different people's understandings. The talk's record is Vimeo's uncorrected automatic captioning, dated 2025.