This paper provides an analysis of the characteristics of complexity in medical language. Complexity allows a greater density of informational content, and a more efficient transmission of information among experts. However, if the ratio between informational content and effort required to understand it exceeds a determined threshold, complexity may impede communication rather than aid it. This so called “hypercomplexity” creates a barrier in communication, not only between healthcare professionals and unqualified persons, but also among specialists. For the classification of a text the authors propose a complexity scale, based on the linguistic opaqueness and the typology of the text. The impact of the complexity level on the result of a communication will be shown on examples taken from a corpus of educational material (informed consent forms and pharmaceutical package inserts).