The hidden web and the fentanyl problem: Detection of ocfentanil as an adulterant in heroin

Pol Quintana, Mireia Ventura, Marc Grifell, Alvaro Palma, Liliana Galindo, Iván Fornís, Cristina Gil, Xoán Carbón, Fernando Caudevilla, Magí Farré, Marta Torrens

Research output: Contribution to journalArticleResearchpeer-review

53 Citations (Scopus)


© 2016 Elsevier B.V. Background The popularization of anonymous markets such as Silk Road is challenging current drug policy and may provide a new context for old issues, such as adulteration of heroin with fentanyl derivatives. The aims of this paper are to report the presence of ocfentanil, a novel, potent, non-controlled fentanyl analog, in samples sold as heroin in the hidden web, and to summarize the effects reported by users. Methods In 2015, four samples allegedly bought as heroin in cryptomarkets of the hidden web were sent to Energy Control for analysis. Energy Control is a Spanish harm reduction NGO that offers anonymous drug checking with the purpose of adapting counselling to the specific substances present in the drug and monitor the drug market. Identification was performed by GC/MS and LC/MS/MS. We contacted the submitters of the samples and performed an Internet search to retrieve additional information. Results One sample contained ocfentanil, caffeine and heroin. Three samples contained the aforementioned substances plus paracetamol. Two out of the four contacted users reported distinct short acting, opioid-like effects. No fora discussion could be found about the effects of ocfentanil, neither web pages nor individuals advertising the substance. Conclusion We report the presence of a new substance detected in the hidden web as an adulterant of heroin, ocfentanil. It has short acting opioid-like effects, roughly the same potency as fentanyl, and can be injected, snorted or smoked. Severe side effects have been associated with its use, including one death. No discussion about this substance could be found in the Internet, which suggests this substance has not been sold as such. Available data about purities of drugs purchased in cryptomarkets suggest that adulteration is not a severe problem and this agrees with users’ perceptions. However, this study suggests that adulteration is a real threat not only at the street level, but also for users that buy substances in cryptomarkets, and suggest the need for harm reduction initiatives in this setting.
Original languageEnglish
Pages (from-to)78-83
JournalInternational Journal of Drug Policy
Publication statusPublished - 1 Feb 2017


  • Adulteration
  • Dark web
  • Fentanyl derivatives
  • Heroin
  • Hidden web
  • Ocfentanil


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