Objective:Patient information leaflets (PILs) are widely used to reinforce or illustrate health information and to complement verbal consultation. The objectives of the study were to assess the readability and presentation of PILs published by Allergy UK, and to conduct a longitudinal assessment to evaluate the impact of leaflet amendment and revision on readability.Methods:Readability of Allergy UK leaflets available in 2013 was assessed using Simple Measure of Gobbledegook (SMOG) and Flesch-Kincaid Reading Grade Formula. Leaflet presentation was evaluated using the Clear Print Guidelines of the Royal National Institute of Blind People (RNIB) and the Patient Information Appraisal System developed by the British Medical Association (BMA). Changes in the leaflets' readability scores over five years were investigated.Results:108 leaflets, covering a wide range of allergic conditions and treatment options, were assessed. The leaflets had average SMOG and Flesch-Kincaid scores of 13.9 (range 11-18, SD 1.2) and 10.9 (range 5-17, SD 2.1) respectively. All leaflets met the RNIB Clear Print guidelines, with the exception of font size which was universally inadequate. The leaflets scored on average 10 (median 10, range 7-15) out of a maximum of 27 on the BMA checklist. The overall average SMOG score of 31 leaflets available in both 2008 and 2013 had not changed significantly. The process of leaflet revision resulted in 1% change in readability scores overall, with a predominantly upward trend with six leaflets increasing their readability score by >10% and only three decreasing by >10%.Conclusion:Allergy-related patient information leaflets are well presented but have readability levels that are higher than those recommended for health information. Involving service users in the process of leaflet design, together with systematic pre-publication screening of readability would enhance the accessibility and comprehensibility of written information for people with allergy and their careers.