Initiatives to address bullying in science (see, for example, Nature 571, 14–15; 2019) should extend to the conduct of peer reviewers, particularly given the impact of toxic reviews on the mental health of researchers (see go.nature.com/2z2urcx).

Learning to accept criticism is part of surviving the fierce competition in research. But an invitation to review the work of a peer, usually anonymously, is not a licence to patronize, intimidate or otherwise act in a way that would be unprofessional in the workplace. Such reviews are unnecessarily discouraging, particularly to an early-career researcher with limited experience of the system.

Journals and editorial boards must accept their responsibility to guide positive reviewer behaviour and constructive feedback. Some journals provide clear ethical guidelines for reviewers (see, for example, go.nature.com/2kjbjjr and go.nature.com/2kmqngv). Others — including Nature — need to devote more webspace to ensuring that reviewers provide important criticism and abide by high standards of integrity and impartiality (see go.nature.com/2h2osn4).

Why not prominently display a code of conduct at the start of a review? Editors must not turn a blind eye to reviewers who fail to meet ethical expectations; neither should authors feel compelled to accept poor treatment.