Today a former addict and dealer speaks out about why she took the nasty substances - and how she endangered her community to satisfy her extreme cravings.
And we hear from a father who has watched his daughter spiral deeper and deeper into addiction - even being pregnant didn't stop her.
When the synthetic drug craze started Emma* hated everything about it.
She was "very anti" the drug and vowed never to use it.
And then, almost in the blink of an eye, she was using up to an ounce a day with her partner and running a "synnies shop" from their family home to fund their $1000-a-week habit.
"The first time I tried it I didn't actually like it," she said.
"I completely freaked out, I had no control over my body, it was scary.
"But after a couple of times I learned to handle it."
Emma is not the woman's real name.
The Herald has agreed not to name her to protect her children.
"I wasn't aware when the addiction actually started, but once I started it was really, really difficult to stop."
When she used synthetics she felt "euphoric", like she could do anything.
She'd been a casual cannabis user over the years and liked the "kicked back" feeling she got when she smoked a joint.
But synthetics gave her a different buzz.
"It's hard to explain... I was quite active, it gave me a lot of energy.
"But when I was using them I was completely aware of everything I was doing, even if I couldn't control it."
She would get grumpy and irritable when she needed a hit and sometimes drove around five or six sellers within a 20 minute period to buy her drugs.
"If I didn't have it, it would trigger my aggressive side," she said.
"I didn't go out beating people up, but I got really agitated."
The woman and her partner were both addicted synnies, as they are known by users, and were spending up to $1000 a week on their habit - going through about an ounce of the substances each day.
She managed to keep up work, caring for her children and no one outside her home was any the wiser.
To ensure they could keep up the payments for their drugs, the couple started selling synthetics.
"We had to find some way of paying for this addiction that we had," she said.
"But we didn't think of it as an addiction at the time."
She said there were always plenty of people ready to buy, and the money was easy.
"In a month we went from scoring it to running a full on shop, 24 hours, seven days a week.
"We were never worried about getting caught, and if we did, we had a back up plan so that we could be back selling from another location within hours."
She said that's how most dealers operated, so when police did busts and arrests, it wasn't making a huge difference.
They purchased the drugs by the pound from "a source" who would import powder and chemicals and mix them with damiana leaf.
Damiana is a Mexican shrub that can also be smoked for a euphoric effect, or consumed as a tea for relaxation.
It is legal in New Zealand.
The chemicals added to the leaves in New Zealand include AMB-FUBINACA - a very potent substance that activates cannabinoid receptors in the brain, resulting in a cataleptic or seizure-like state.
"We never made the mixes but if clients said it was too strong we would add more damiana."
The last time she used was "petrifying".
The woman and her partner went away for a weekend and had "a session" in their hotel room.
"We were having cones and I was literally paralysed for half an hour - I couldn't move, I didn't feel like my feet were touching the ground.
"I had no control of myself, it absolutely freaked me out and that was it for me."
She went cold turkey, too scared to feed her addiction any longer, and has not used since.
It took her partner another eight months before he was ready to quit.
That was agonising for the woman.
"He still believed it was controllable... but he was nearly having heart attacks and so many times people would call me, they thought he was going to die.
"I couldn't go to sleep at night because I didn't know if he was going to die... it was absolutely devastating to sit and watch him literally sit there every day in the kitchen just getting high.
"He couldn't cook, he couldn't clean, he couldn't do anything - all of his focus was on bagging up the product and getting it out on the streets, and getting high.
"In the end I gave him an ultimatum between our family and the addiction."
The woman has now been clean for two years, but lives every day with the horrendous guilt of having sold the muck to others.
"I believe karma is going to come back and get me for the dangerous stuff I put into my community," she said.
She now puts her energy into helping people and does as much community work as possible to make up for her past.
She wanted other addicts to learn from her story.
"I lost part of myself when I was an addict," she said.
"You really need to look in the mirror and listen to the people trying to support and help you.
"They are not hating on you, they all want what is best for you - they love you and it's not that they don't want you to have fun, they just want you around to live your life."
Synthetic spiral: a father's fear
His daughter dabbled in meth, then moved to a cheaper alternative - synthetic drugs.
Even being pregnant didn't stop her using the deadly substances.
Now she's lost everything.
Her baby, born earlier this month, was taken straight into care; she has nowhere to live; she's a mess.
And her father can do nothing to help her.
It started four years ago when his daughter "fell in with some bad company", he told the Herald.
"She had everything," he said.
"She wasn't short of love or care.
"She was a beautiful, intelligent woman - but now she looks 90 and her intelligence is gone; the only thing there is the addiction."
His daughter is in her 20s but the Herald has agreed not to identify her to protect her safety.
Her father fears every time he gets a call about her that it will be the last call, it will be the call to say she's dead.
About four years ago the woman started to associate with a gang member, started using methamphetamine.
Once she got hooked though, she could not afford the addiction so she turned to synthetic drugs - a much cheaper option.
She hasn't stopped using since.
"She spiralled," her father said.
"Synthetics were cheaper, and she's on a benefit so that's what she does.
"And they will take anything for them."
He said he'd purchased her at least eight phones and top up cards which have all been traded for synthetics.
She even gives away her food for a fix.
"They'll contact her and then they meet at a park, a petrol station, a McDonald's carpark to do the deal," her father said.
He has spent countless hours driving around their home city looking for her, approaching known synthetic dealers and begging them not to sell to her.
He's also trawled through his phone after she's used it, contacting the people she's called and pleading with them to cut her off.
He's taken the names, numbers and addresses to the police, tried to have her put in mental health facilities - you name it, her father has done whatever he can to keep her safe.
But she's not interested, her addiction is too strong.
"She's as cunning as 10 foxes," her father said.
"And one of the main problems is she's in denial, she never admits she's got a problem.
"I will never give up though," he said.
It broke the man's heart to see his daughter in such a situation and he said it worried him every waking minute.
"On these drugs... it's not my daughter.
"She won't make eye contact... she's been in trouble in court.
"My biggest fear? Death... and that would kill me, it would really hurt me."
He said the problem was much bigger than anyone really knew.
"It's bloody big... it's extreme."
Chief Coroner - each case is a tragedy-
A dramatic spike in synthetic cannabis-related deaths in Auckland prompted a public warning from Chief Coroner Deborah Marshall.
In July she issued a public safety warning after seven deaths thought to be related to synthetics drugs were referred to her.
Last week she revealed that number had rocketed to at least 20.
"Each case is a tragedy for the family and friends of those left behind," Judge Marshall said.
"While many deaths have occurred in Auckland, a number of cases in other parts of New Zealand have also been reported to Coronial Services.
"Using any illicit drug carries risks, and in the case of synthetic drugs, they are known to cause potentially fatal seizures.
"I urge anyone considering using this drug not to do so, and for those who are, to reach out to services that might assist them."
Police are also pleading for the community to help them stop the flow of the drugs.
Detective Inspector Scott Beard called on anyone with information about manufacturers or dealers to contact police immediately.
"We need your help to catch these offenders and to hold them to account," he said.
"It is a dangerous drug that we know is a synthetic compound usually manufactured overseas.
"Those taking it, are taking a huge risk because you do not know where it has come from, or the level of dosage."
In July ambulance staff in Auckland told the Herald they were seeing about 20 users a day suffering "life-threatening effects" from the illegal drug.
What is synthetic cannabis?
Smokable products containing varieties of plant matter that have been infused with synthetic cannabinomimetic substances.
Examples include the brand Kronic.
They act in a similar way to cannabinoids naturally found in cannabis such as tetrahydrocannabinol (THC).
The products were intended to be a legal alternative to cannabis, but are now banned.
Synthetic marijuana acts on the same brain cell receptors as natural marijuana, but are more likely to cause hallucinations and heart problems.
Synthetic marijuana has also been linked to an increased risk of seizures.
Effects include, but are not limited to: decreased motor coordination, fast or irregular heartbeat, disassociation, dizziness, paranoia, psychosis.
Use of synthetic cannabis in New Zealand has also been linked to renal failure and heart failure.
Where to get help
If you, or someone you know, is using synthetic cannabis, police urge you stop immediately and seek help if needed by contacting your local GP or by ringing the Alcohol and Drug Helpline on 0800 787 797 or text 8681 7 days a week to speak to a trained counsellor.
If you or someone else is in immediate danger call 111.