When legal highs came onto the market, he switched to them. Gradually his use became more frequent and as his tolerance to the substances grew, it wasn't unusual for Leyton to smoke bag after bag after bag of whatever he could lay his hands on.
He'd beg, steal and borrow to pay for his habit. He's committed burglaries and sold drugs to pay for his K2 habit. He devised elaborate plans to obtain the substances without paying for it. "He's lucky he has come out of this without a criminal conviction," says Helen.
Helen tried everything to help her son. She got mental health services involved and managed to get Leyton into Auckland's Odyssey House, an addiction treatment provider. However, he lasted just 24 hours there after he became aggressive and threatening towards staff.
"You do feel powerless but then it got to a point where I realised that even though I'd go on at him all the time that I had to just let it go and let him hit rock bottom and hopefully then be able to pick the pieces up. Which is a horrible thing to have to do but you get to the point where you feel numb."
Helen is quiet, contemplative as she talks about that fateful day in April. "At that point Leyton was highly agitated and aggressive and was in his room self-harming. They made the decision to section him and commit him to Henry Bennett. I couldn't watch. I was in another room dry reaching. They came in with a Taser and had to subdue him and get him on the floor to minimise the risk of him hurting anyone."
And while that's something Helen couldn't watch, Leyton has seen his share of horrific and explicit episodes during his K2 journey. There's the boy who "dropped dead" in front of Leyton. "He had no pulse, no breath, nothing." Panicking, Leyton's mate dragged the boy to his feet before Leyton "sucker punched" him in the chest. The boy gasped and began to breathe again. Then there's the girl who was convulsing so violently that her arms were twisting involuntarily. Leyton could hear the bones snapping.
Leyton's seen children as young as nine smoke synthetic cannabinoids. He knows of P users who've switched to K2. "I know a couple of people who smoked way harder drugs than marijuana and they stopped the hard drugs and went to legals because it was cheaper, more efficient."
Being admitted to HBC was a wakeup call for Leyton. "If he hadn't ended up in there, he'd be dead or in jail," says Helen.
Helen visited Leyton when he was in a secure ward for the first couple of days while he "calmed down". "To see your son like that - it's just a big room with a steel toilet and a mattress on the floor."
Leyton was discharged five days later, but the next day was back at the dairy around the corner where he sourced most of his legal highs. Literally a stone's throw from his home, the dairy refused to sell to Leyton after Helen explained how sick the drugs had made her son. Helen dragged Leyton back home. "He was literally banging his head against the wall. I just had to get in his face and say 'you need to take one of your pills and calm down or you'll be back in hospital by tonight mate'. We got through it."
They're still getting through it. The withdrawal symptoms - headaches, nausea, anxiety, aggression, intense cravings, pins and needles all over his body, parts of his body feeling completely numb - lasted at least a month. His skin has cleared up and his eyes are no longer bloodshot. A few of Leyton's friends have quit K2 also, others haven't. But he's disassociated himself from all of them.
"He's wrapped up in cotton wool at the moment," says Helen. Leyton sees a team of specialists including a doctor, a registered nurse, a drug and alcohol counsellor and a psychologist. Asked to leave school a few years ago, Leyton hasn't completed his education but he's looking at perhaps working part-time to keep him occupied.
Leyton says he knew the pain he was causing his mother. "I did care but I didn't know how to show I cared. I was in my own hell. The legals were my personal demon. You try them, you're locked in."
Helen's belief in her son is what kept her going. "I just keep going because I knew my son was a good boy. He still had a heart in there. I'd cry myself to sleep many times. I'd wonder how I was going to keep going but you just do."
Helen says Leyton is "like a different kid". While the journey isn't yet over, the pair is confident that Leyton is on the right track. He wants to educate other people - especially school students - about the dangers of legal highs.
Helen is supportive of that but says the law change that's coming that will see legal highs removed from shelves doesn't go far enough. "It's just a joke. They need to ban it completely. I can't understand why the Government has let this happen in the first place ... the strain it's putting on the police, the mental health system, and the emergency departments. It needs to be classed as a Class A drug."