Background <p>Androgens from the black market are often produced in clandestine laboratories without adherence to hygienic manufacturing processes. Consequently, users may face an increased risk of developing injection-related infections caused by microbiological contamination. This study aimed to determine the presence of microbiological contamination in androgens from the black market.</p> Methods <p>Characteristics of submitted androgen product were registered. Androgen products were submitted to aerobic and anaerobic bacterial culture using direct inoculation of agar plates and enrichment using BD BACTEC™ Peds Plus Medium blood culture bottles. Participants who submitted products were monitored for injection-related infections.</p> Results <p>Bacterial contamination was detected in two of 22 used multidose vials (9%) and one of 41 unused ampules and multidose vials (2%). Identified species included <i>Bacillus spp.</i>, <i>Staphylococcus epidermidis</i>, <i>Staphylococcus warneri</i>, <i>Staphylococcus saprophyticus</i> and <i>Micrococcus luteus</i>. None of the participants developed injection-related infections linked to contaminated products.</p> Conclusion <p>Both used and unused androgens from the black market can contain bacteria. This can put users at risk for serious injection-related health problems such as abscesses. This study underlines the importance of warning androgen users about these underrecognized injection-related risks.</p> Trial registration <p>Study number: NL77191.028.21. Registration date: 2 June 2021.</p>