Background <p>Health literacy is a key determinant of individuals’ ability to use medications safely and correctly. The readability of patient information leaflets (PILs) plays a critical role in patient safety and treatment adherence. Inadequate readability may limit patients’ understanding of medication instructions and increase the risk of misuse. This study aimed to comparatively examine the readability levels of patient information leaflets for medications commonly used in the United Kingdom, Germany, and Türkiye.</p> Methods <p>A cross-sectional design was used in the study. The research was conducted using a document analysis approach. Patient information leaflets for 20 medications with identical names, dosages, and pharmaceutical forms in the United Kingdom, Germany, and Türkiye were analyzed. The sections “What is X and what is it used for?”, “What you need to know before using X”, “How to use X”, “Possible side effects”, and “How to store X” were examined separately. Readability was assessed using the Flesch Reading Ease formula for English texts, the Amstad formula for German texts, and the Ateşman formula for Turkish texts.</p> Results <p>Mean readability scores corresponded predominantly to the “difficult” or “very difficult” readability categories in four of the five analyzed sections in Germany and Türkiye and in three sections in the United Kingdom. Texts under the headings “What you need to know before using X” and “Possible side effects” were most frequently classified as “difficult” or “very difficult,” largely due to long sentence structures and dense technical terminology. Although variations in readability scores were observed between countries, the overall findings suggest that the extensive use of long sentence structures and technical terminology may limit the comprehensibility of the leaflets for the general public.</p> Conclusion <p>Despite existing regulatory requirements, patient information leaflets prepared in different linguistic and healthcare system contexts are not sufficiently accessible to the general public. Simplifying leaflet content and restructuring it in a more user-centered manner—both linguistically and structurally—is essential to promote safe medication use and protect public health. These findings may guide regulatory authorities and pharmaceutical companies in improving policies and practices related to leaflet readability.</p> Clinical trial number <p>Not applicable.</p>