All medical treatments have potential harms as well as benefits, and it’s vital that everyone has a good understanding of what these might be, how dramatic they might be, and how likely. In fact, in the UK, the Montgomery judgement in the supreme court in 2015 has made it a legal necessity for patients to be given comprehensible, personally relevant information about all reasonable treatment options – including none. So, how should we ensure this good, clear communication of relevant evidence?