Different expressions are used to describe the process of informal access to antiretroviral drugs (eg, via the Internet or acquaintances) for HIV preexposure prophylaxis (PrEP):“informal use”, 1” informal PrEP”, 2 “off-label PrEP”, 3 “non-prescribed PrEP”, 4 “DIY PrEP”, 5 and “wild PrEP”. 2 This lack of consistent nomenclature makes it difficult to develop an accurate understanding of the nature of the process and its public health implications. To improve consistency for future research and public health initiatives, this process should be referred to as informal PrEP. Informal use implies that PrEP could have been used incorrectly. Since only a few countries have approved Truvada (tenofovir disoproxil fumarate and emtricitabine; Gilead, Foster City, CA, USA) as PrEP, people have developed different techniques to access the molecules that make up Truvada, such as purchasing generic antiretroviral drugs online. However, although users might be using so-called informal channels, they might still be using PrEP correctly, with the supervision of a health-care professional, and be frequently tested for HIV and other sexually transmitted infections. In Canada and South Africa, for example, physicians were prescribing Truvada as PrEP before its official local approval. Characterised as offlabel, this terminology is misleading since physicians can prescribe Truvada as PrEP based on the US Centers for Disease Control and Prevention (CDC) guidelines. In many countries, people can obtain a physician’s prescription for Truvada by asking for postexposure prophylaxis but using this treatment as PrEP, making the expression nonprescribed inaccurate. Informal PrEP has various public health implications, which have already been addressed in the published literature. 2 Additional research is needed