Suspected overdose deaths spiked again in March, reaching the province's second highest monthly total to date, according to the B.C. Coroners Service.

A total of 161 people are believed to have died from drug overdoses in March, a 58 per cent increase over the month before.

Only December 2016 saw more fatal overdoses, with 162. So far this year, there have been 391 deaths across B.C., with about a quarter (102) happening in the the City of Vancouver.

A graph from the B.C. Coroners Service shows a dramatic spike in overdose deaths. (B.C. Coroners Service)

Fentanyl remains a major factor in B.C.'s deadly drug crisis, according to the latest stats.

The coroners service says the opioid was detected in post-mortem testing on 83 per cent of victims who died in the first three months of 2018.

Most of the overdose victims this year have been male (82 per cent) and between the ages of 19 and 49 (69 per cent.)

The vast majority of people — more than 90 per cent — have overdosed indoors. No one has died from an overdose at a supervised consumption site or an overdose prevention site.

In a news release, the coroners service said it "urgently reminds" people using illicit drugs to never consume alone, and always have someone nearby who can administer naloxone or call 911.