Cychlorphine, Explained: The Deadly Opioid Spreading from Toronto to London

How an obscure compound became a street opioid, the deaths it has already caused in London, and the counterfeit pills turning up in the US and Canada

In early December, health authorities confirmed that three people in the northern area of Camden had died, in recent weeks, from a synthetic opioid most frontline workers had never heard of: cychlorphine.

The first fatality dated back to late October, the second to mid‑November, the third to the end of the month; yet the formal warning to services and the public did not arrive until December. It took this long for Camden Council and local treatment providers to finally name cychlorphine as a potent, lab‑confirmed synthetic opioid now present in the British capital.

Yet London is not the only city scrambling to understand what cychlorphine means for its drug market. In Toronto, Canada, the first formal warning came at the start of October, when the city’s drug checking service quietly confirmed that a pill sold as Percocet contained no oxycodone at all, only cychlorphine.