Interior Health has issued a special drug alert about a light yellow powder being sold in Nelson as down or fentanyl.
They say it contains 21 per cent flurofentanyl, whose potency is not well understood.
“It can be more potent than standard fentanyl,” they said. “This means this drug could be very strong.”
It presents a high risk of fatal overdose or loss of consciousness, the health authority said.
The warning is in effect until Sept. 17.
A general alert issued for the West Kootenay has also been extended until that day.
The health authority said there have been “numerous” fatal and non-fatal drug poisonings in Nelson, Castlegar, and Trail, although they did not attribute it to any specific substance.