Sherri Kent's photo with her dying 22-year-old son carries a warning to other parents.

Last month, Canadian mother Sherri Kent received a devastating phone call: her son Michael was in hospital on life support.

“You know, it doesn’t really click in that this is real and this is happening,” she tells CBC. “They tell you that your boy is never going to wake up.”

Michael was 22 years old. His mother describes him as a kind and trusting person.

“Michael had a compassion for everybody,” she says. “He’d give you the shirt off his back. He was that type of child.”

Michael is believed to have died from an overdose of the drug fentanyl, a powerful painkiller. “My son was not an addict,” Kent wrote on Facebook. “He made a mistake that cost him his life.”

Michael was living with his sister. Kent says he had used drugs in the past, but nothing except marijuana for the previous four months.

The day before he overdosed, Michael and his sister bumped into a man who offered him drugs. His sister forced him to refuse. But the next day, when his sister was napping, Michael went and found the man.

“This gentleman had told my son he had some really strong heroin," Kent says.

The two took drugs together in the toilets of a nearby store. According to Kent, the man got “messed up” and left Michael in there on his own.

“About 20 minutes later, he was too scared to go back and check on my son… so he ran for the people who own the store to unlock the door and that's when they found him.

"He was already blue in the lips. By the time the ambulance got there, he was in cardiac arrest.”

Michael was on life support for a week. Kent was by his side. “They made me a spot on the bed where I could lay with my son and talk to him,” she says.

Kent made the decision for Michael to become an organ donor. Once his life support was switched off, his organs were given to five people.

A week ago, Kent posted a photo of herself and Michael on Facebook. The photo shows her cuddling up to Michael in hospital.

“This is where I told my son I was still proud of him,” she explains.

In the post, Kent says her son died from a fentanyl overdose, which is what she was told by police.

“I just want to make everyone aware of the epidemic that’s going on right now that's killing five to seven people a day in every city in Canada. It’s out of control and there is no way to protect our children from this other than to warn them of the dangers of drug use today.

"I’ve lost my son to this horrible tragedy and want to make parents aware that it can happen to anyone who decides to touch anything that can be snorted up your nose.”

Kent’s post has had more than 100,000 shares.

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Fentanyl is an opioid drug, similar to morphine, only much more powerful. Music legend Prince died from an accidental overdose of fentanyl.

In Australia, the drug is available by prescription only, and is used by people suffering chronic, severe pain, due to cancer, major trauma or other serious conditions. It comes in several different forms, including a patch or a lozenge. Some people use fentanyl recreationally, often as a substitute for heroin. But the danger is that there’s very little difference between the amount needed to get high and the amount that causes an overdose.

Last year it was reported that prescription painkillers like fentanyl were making up 70 per cent of accidental opioid deaths in Australia. The other 30 per cent of deaths were due to heroin. Kent believes naloxone kits should be more readily available. Naloxone can be injected to reverse an overdose of fentanyl, giving people time to get medical help.

“This drug can take you within 10 minutes,” Kent says. “Young people are probably the hardest people to make understand that this can cost you your life.”