Polysubstances include drugs that are cut or mixed with other drugs in through manufacture or ingesting. The websites provides information and facts on polysubstance use, including drugs mixed or cut with fentanyl.

DEA's drug fact sheet on fentanyl. It provides background information such as the origins, street names, how it affects the human body, and legal status of the drug.

Provides background on both pharmaceutical and illegally made fentanyl.

Article describing the properties of fentanyls and how they affect the organs and body systems.

Providing information about pharmaceutical fentanyl and related information.

Government website providing general information about Fentanyl and the opioid overdose crisis.

PubChem is an open chemistry database at the National Institutes of Health (NIH) and provides information on compounds, substances, pathways, bioassays, literature and patents.