Fraser Health is warning drug users to use less than they normally would after first responders saw a dozen overdoses Friday night.

An alert was issued to service providers and community organizations in north Surrey after 12 overdoses were reported in a four-hour span. It is also possible that number is higher as not all overdoses are reported.

Fraser Health has so far not been able to identify any commonality in the substances involved and it is asking people to be “very cautious” if consuming drugs.

It suggests people use less than normal if taking certain prescription medications and/or are using after there’s been a non-use period of time.

It is reminding people not to mix drugs and alcohol, and not to use alone.

As street-quality substances can be unpredictable, it also encourages doing testers, going slow, and trying to use a consistent, reliable dealer.

The health authority said many of the overdoses were reversed using naloxone, which is a medication that is free to people who use drugs.

It cannot report if any deaths occurred in the community as it wouldn’t immediately be reported to the authority.