A dozen overdoses within a short period has a medical health officer warning drug users to beware of contaminated drugs in Surrey, B.C.

Dr. Shovita Padhi of Fraser Health says first responders including firefighters and ambulance personnel reported the unusual increase in overdoses Sunday and believed people were using cocaine contaminated with a powerful opioid like fentanyl.

She says people who typically use cocaine should be extra cautious because they may be at greater risk of overdosing if they have no experience using opioids and therefore no tolerance to the drug.

Padhi is urging drug users to not use alone or have the overdose-reversing drug naloxone with them.

Drug users are also being encouraged to have their substances tested at SafePoint, a supervised injection site that is open from 7 a.m. to 1 a.m., or at public health units between 1 p.m. and 4 p.m. on weekdays.

The BC Coroners Service says 210 people fatally overdosed in Surrey last year, up from 178 fatalities a year earlier.