Background
Most medicines require the patient to have a certain amount of information, if they are to use it safely and effectively¹. Certain warnings on prescribed and over-the-counter medicines are subject to legal and professional regulation². Some of the language used is technical, heavy with jargon, and has difficult sentence structure. The wording often defies plain English guidance and evidence from psycholinguistic research. Understanding may be improved by using common words, short sentences and an active tense³.

Paracetamol is of particular interest, due to the risks associated with overdose. This study looks at two mandatory wordings required with over-the-counter paracetamol packs whose wording seemed poor (see below). We devised alternative versions that followed good practice in information design and tested understanding in customers of a pharmacy.

Warning 1

• Original: Immediate medical advice should be sought in the event of an overdose, even if you feel well, because of the risk of delayed, serious liver damage.
• Revised: Too much paracetamol may damage your liver. If you take too much, see a doctor straight away. Do this even if you feel well.

Warning 2

• Original: If symptoms persist consult your doctor.
• Revised: If you do not feel better after 2 days, see your doctor.

Method
We tested understanding in 144 consecutive adult customers of a community pharmacy. Each person was shown one version of each warning and asked which of 3 interpretations best described what they thought it meant. Order of stimulus presentation and choice of actions was counter-balanced. Data were analysed by logistic regression.

Results
Fewer people chose incorrect interpretations for revised versions of both warnings, compared with the current wording. For Warning 1 the Odds Ratio was 0.32, and for Warning 2 the Odds Ratio = 0.37.

Conclusion
Consumers' dependence on written instructions is increased when a medicine like paracetamol has been bought, rather than prescribed. These results show that it may be possible to increase people's understanding of this information by using evidence-based plain English wordings. Further study might use a different response format, in which subjects give an unprompted interpretation of the tested label. Research is also needed to see whether current and alternative labels have a differential effect on medicine-related behaviours.

1. Raynor DK. The influence of written information on patient knowledge and adherence to treatment. In: Myers L, Middence K (Eds): Adherence to treatment in medical conditions. London, Harwood, 1998.
2. Medicines Ethics & Practice. Royal Pharmaceutical Society. London, RPSGB, 2000.
3. Raynor DK. Writing patient information�a pharmacist's guide. Pharm J 1992; 249: 180-2.