New York City will expand the availability of a life-saving medicine that reverses the effects of opioid overdose, providing it without prescription as part of a campaign to combat substance abuse, officials announced Monday in Staten Island.

Opioid-linked overdose deaths in the city have increased by 56 percent since 2010. Opioids encompass heroin and prescription painkillers.

“The deaths are what we all struggle to avoid … but that’s just the tip of the iceberg,” de Blasio said at a YMCA on the borough’s South Shore. “For every death, there are literally hundreds who struggle with addiction.”

Naloxone, which can be used in emergencies, will now be available for purchase for about $50 over the counter at most Rite Aid pharmacies in the city and many independent drug stores, first lady Chirlane McCray said. CVS pharmacies will also eventually participate, she said.

“In order to recover, you need to stay alive,” said City Health Commissioner Dr. Mary T. Bassett, who issued a standing order to pharmacists to dispense the medicine.

The city also is spending $750,000 to distribute kits with naloxone in them to drug prevention programs.

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The city will also train 1,000 medical professionals to prescribe Buprenorphine, which can curb cravings and the effects of withdrawal, McCray said.

The officials were joined by James Brenker, 21, of Staten Island, whose life was saved by Naloxone when he overdosed on a mix of heroin and oxycodone.

Brenker, who said he has watched friends die from overdoses, applauded the city’s initiative. “I felt like no one cared. I know a lot of addicts feel that way,” he said.