Councillors and drug groups in Glasgow and Lanarkshire are to pilot use of the anti-opiate revival drug Naloxone.
Overdoses have claimed more than 30 lives in Glasgow this year
They believe heroin overdose deaths could be halved if addicts' families are issued with the treatment to inject into overdose victims.
The Conservatives have criticised the £20,000 project as sending out a message that drug misuse is acceptable.
It is estimated that most drug overdoses are witnessed by members of family or friends of addicts.
Police have warned that purer heroin on the streets is contributing to a rise in overdose deaths.
In Glasgow alone there were 35 fatalities in the first four months of this year.
Glasgow City Council and the Lanarkshire Drug Action Team have now agreed on pilot projects to provide addicts' families with Naloxone, which reverses opiate harm.
Neil Hunter, general manager of Glasgow Addiction Services, said: "We have to accept that there are some individuals in the city who are unable, at the moment, to benefit from rehabilitation or treatment.
"They are still leading fairly chaotic and high-risk lives and we have to do something to intervene to try to avoid any harmful consequences."
However, Scottish Conservative health spokesman David Davidson said: "It's as if the agencies have given up all hope of getting people away from drugs and getting people back into society."