Whoonga is a drug cocktail in South Africa rumored to contain illicit drugs and HIV antiretroviral (ARV) medication. Although its use may adversely impact adherence to HIV treatment and may have the potential to generate ARV resistance, there is a paucity of research characterizing whoonga. We learned of whoonga during semi-structured interviews about substance abuse and HIV risk at "club-events" known as inkwaris in an urban township of Durban, South Africa. Whoonga was an emerging theme spontaneously identified as a problem for the community by 17 out of 22 informants. Perceptions of whoonga suggest that it is highly addictive, contains ARVs (notably efavirenz), is used by individuals as young as 14, and poses a threat to the health and safety of those who use it, including increasing the risk of HIV infection. Our informants provide preliminary evidence of the dangers of whoonga and reinforce the need for further study.