What is fentanyl and why is it behind the deadly surge in US drug overdoses? A medical toxicologist explains
- Written by Kavita Babu, Professor of Emergency Medicine, UMass Chan Medical School

Buying drugs on the street is a game of Russian roulette. From Xanax to cocaine, drugs or counterfeit pills purchased in nonmedical settings may contain life-threatening amounts of fentanyl.
Physicians like me have seen a rise in unintentional fentanyl use from people...