This letter explores the societal aspects and healthcare implications that underlie thinking about mpox (formerly known was monkeypox), in the 2022 outbreak, as a sexually transmitted infection (STI). The authors examine what underlies this question, exploring what is an STI, what is sex, and what is the role of stigma in sexual health promotion. The authors argue that, in this specific outbreak, mpox is an STI among men who have sex with men (MSM). The authors highlight the need of critically thinking about how to communicate effectively, the role of homophobia and other inequalities, and the importance of the social sciences.