Latest figures show that almost 700 people died in Ireland from an overdose in 2015, with 40% of them not alone at the time.
It comes as the HSE said it wants to educate drug-users and their families about a treatment called Naloxone, that can reverse the effects of overdose.
It is marking International Overdose Awareness Day by hosting free training events around the country in Cork, Dublin and Limerick.
HSE National Planning Specialist Joe Doyle, says the more people know, the more lives are saved.
Mr Doyle said: "The training is specifically targeting drug-users, their peers and their family members. We know that in relation to opioid overdoses, 40% of people were actually with somebody at their time of overdose.
"They tend to be the people who are closest to the person and also we are targeting people who work on the frontline within addiction and homeless services."
A coalition of homelessness and drugs organisations have come together to support the rollout of the nationwide Naloxone training.
Tony Geoghegan, CEO of Merchant's Quay Ireland says Ireland has the fourth highest rate of drug-related deaths in Europe, and Naloxone can really make a difference.
Mr Geoghegan said: "We're encouraging all active drug-users, people who are taking heroin or opiates, and also their friends and family members to learn how to use this Naloxone, because it actually reverses the effects of overdose and saves lives.
"There will be training provided both here in Dublin, but also in Cork and Limerick as part of this initiative around overdose awareness day."