On average, more than four people a day died in May in B.C. from illicit drugs, a death toll the coroner's service says should serve as a warning to people who are not drug-dependent to avoid experimentation.

The service says provisional data show 129 people died in May, down slightly from 136 who died in April.

It says until November 2016, there had never been as many as 100 drug deaths in the province in a single month, but in every month since then, the number of deaths has exceeded 110.

The highest number of deaths came in December, when 159 died.

The service says the powerful painkiller fentanyl was detected in 72 per cent of people who died in the first four months of this year, up from 60 per cent last year.

'Opioid naiveté'

Chief Coroner Lisa Lapointe said people should not casually use illicit drugs because of the risk.

"The number of deaths shows that the risks remain extreme," she said in Friday in a statement.

"The drug supply is unsafe ... and occasional users are at high risk of overdose due to their opioid naiveté."

The highest numbers of deaths were in Vancouver, Surrey and Victoria.

Last year, 967 people died in B.C. from illicit drug overdoses. In the first five months of this year, 640 have already died.