Visual errors in the perception of written drug names can reflect orthographic similarity amongst certain names. Drug names are typically printed in lowercase text. 'Tall Man' lettering, the capitalisation of the portions that differ amongst orthographically similar drug names, is employed in the field of medication labelling and prescribing to reduce medication errors by highlighting the area most likely to prevent confusion. The influence of textual format on visual drug name perception was tested amongst healthcare professionals (n = 133) using the Reicher-Wheeler task. Relative to lowercase text, Tall Man lettering improved accuracy in drug name perception. However, an equivalent improvement in accuracy was obtained using entirely uppercase text. Thus, character size may be a key determinant of perceptual accuracy for Tall Man lettering. Specific considerations for the manner in which Tall Man lettering might be best formatted and implemented in practice to reduce medication errors are discussed. STATEMENT OF RELEVANCE: Tall Man lettering aims to prevent medication errors by reducing visual confusions amongst orthographically similar drug names. It was found that, compared to lowercase text, Tall Man lettering improved accuracy in drug name perception. Character size appeared to be a key determinant of perceptual accuracy for Tall Man lettering.