"Never try it, because it's going to take you," warns a B.C. man who lost both his brother and his girlfriend to fentanyl overdoses.

'He was my role model, he was my world,' says Nick Jansen of his brother Brandon. (Michelle Jansen)

For 19-year-old Nick Jansen, illicit fentanyl is much more than just a toxic and addictive opioid. It's pure evil.

"It just grabs hold of your mind and it destroys you and you can't beat it," says Jansen, who is grieving the loss of his girlfriend, Gwynevere Staddon, 16, who died of an accidental overdose five months after his brother died.

Toxicology reports confirmed fentanyl killed Brandon Jansen, 20, on March 7, and Jansen is certain the results will be the same for Staddon, who died Aug. 7.

Jansen says fentanyl addiction destroys its victims, regardless of their age, race or income.

"The drug doesn't care who you are. It will take you and I believe that's what happened to her," he said in an interview with CBC News.

He watched illicit fentanyl consume his older brother last winter and then Staddon, who he'd been dating for several months.

Gwynevere Staddon, shown with Nick Jansen, died from a suspected fentanyl overdose on Aug. 7. (Facebook/Nick Jansen)

"She lit up a room whenever she walked in. She was the funniest, sweetest and most caring girl," said Jansen.

Addiction 'happens within a week'

He says he watched with worry how quickly the Coquitlam gymnast got hooked, and how sick she got when she tried to stop.

"You're going to want to jump out of your own skin, withdrawing full blown.... It happens within a week and you're not going to be able to stop because it's already got you," he said.

'She hid her addiction,' says Nick Jansen of girlfriend Gwynevere Staddon. (Michelle Jansen)

A dose the size of a grain of salt has sent hundreds to early graves across Canada, and forced B.C. to declare a public health emergency in April, just a month after Staddon's brother died.

Hard core addicts, teen experimenters and weekend partiers have been dying at an alarming rate, most after unknowingly consuming home-made fentanyl smuggled out of China.

READ MORE: Our continuing fentanyl coverage

Even though addicts know the risk, they also know a quick call to a dealer will stop the sweating, vomiting, and what many describe as the unbearable pain of withdrawal.

"Why feel like crap when I can feel good for $20? Then they're going to spend that $20 a day, day after day," said Jansen, who says he saw the same patterns with his brother and Staddon.

Girlfriend vowed to get clean

'She sat with me at the funeral,' says Nick Jansen of girlfriend Gwynevere Staddon, seen here the day of his brother's memorial service. (Michelle Jansen)

Jansen's frustration and grief is compounded by the fact that Staddon knew the risks of illicit fentanyl, because she helped him get through his brother's death.

"She was supporting me through the whole thing. She was holding me saying — this is enough," he said.

"That made me feel hopeful that this was the end, that this was the last bitter pill I would have to swallow with this fentanyl crisis in my circle of family and loved ones."

But it wasn't. Staddon's repeated promises to stop using were no match for the power of her addiction. He said his family and hers tried to find a rehab facility, but no publicly funded beds were available.

"We tried calling a number of places and the only place that would take her was a detox facilty," said Jansen.

A barista found her, unresponsive, in a Starbucks bathroom in Port Moody. Paramedics were unable to revive her. Several of Staddon's family and friends say she told them her body could handle fentanyl and she would never overdose.

Jansen urges others to never touch the drug.

Nick Jansen says he never thought he'd be suffering a second loss in B.C.'s fentanyl crisis. His girlfriend died five months after his brother. (Michelle Jansen)

"You're not invincible to it, it's going to affect you, like it does everyone else, and there's no getting around it," he said.

Dealers use deaths to boost sales

What's worse, he suspects dealers who sell the potent opioid treat the death of a client as a marketing opportunity.

"Other people who are so far into addiction think, oh my god, that is some strong stuff. It's better than all the other stuff I'm getting, so they go and buy that," said Jansen, who says he's seen deep addiction up close.

You're self-sabotaging, you're killing yourself. - Nick Jansen

"It's the nature of the addiction, you're self-destructing, you're self-sabotaging, you're killing yourself."

He is now working with his mother to raise awareness and lobby for more treatment beds.

They created the Brandon Jansen Foundation and have become vocal advocates for young people suffering from addiction.

CBC News Investigates

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