EMMA ALBERICI, PRESENTER: The family of a teenager who leapt to his death after taking a synthetic drug is pleading with authorities to ban it before another life is lost.

Seventeen-year-old Henry Kwan jumped from a balcony at his Sydney home two days ago after reportedly buying the drug from a school friend.

But outlawing the synthetic hallucinogen might be easier said than done, as it is mostly purchased legally online and as Ellesa Throwden reports, police appear powerless to stop the trade.

ELLESA THROWDEN, REPORTER: Stephen Kwan's only son is gone and he's struggling to understand why a drug that mimics LSD is legal.

STEPHEN KWAN, FATHER: It's so easily available and it's killing.

ELLESA THROWDEN: Henry was a month shy of his 18th birthday. His father says he was top of his class and wanted to be a lawyer. But on Wednesday night, Henry's decision to take a synthetic hallucinogen known on the internet as 25B-NBOME, turned his parents' high hopes for his future to despair.

STEPHEN KWAN: He took off his clothes and then he said he want to fly, so my wife and daughter try to get hold of him. But couldn't. So he fell dead.

ELLESA THROWDEN: The drug appeared on the police radar in March its easy access, cheap price and the severe reactions experienced by those who've taken it have authorities scrambling. Up until today the State's top drug detective thought it could only be purchased on black market web sites like Silk Road, which are difficult to access. This is just straight off the regular internet after Googling. Are you concerned by that?

NICK BINGHAM, DET SUP, NSW POLICE DRUG SQUAD: I am, we generally thought these products were sold on dark sites like Silk Road but this is just a general site that's accessible to everyone.

ELLESA THROWDEN: As all levels of government try to sort through the legal grey area surrounding synthetic drugs they can do little but warn of the risks.

TANYA PLIBERSEK, HEALTH MINISTER: Rolling the dice and putting these things in their bodies, it just is extraordinary, really, the time of risks people are taking.

ELLESA THROWDEN: Researchers say even if this drug is outlawed, authorities face a challenge of keeping up with an industry that continually moves ahead of the law.

LUCY BURNS, NSW NATIONAL DRUG AND ALCOHOL RESEARCH CENTRE: You know we have seen our ecstasy market decrease and what we've seen is at the same time this new set of drugs emerge.

ELLESA THROWDEN: Henry's family hopes that by sharing his story, parents will talk to their children about the dangers of buying legal drugs on-line.

STEPHEN KWAN: Everybody need to do something to prevent this to happen again with other families.

ELLESA THROWDEN: Stephen Kwan says he won't give up his fight until the drugs are outlawed.

Ellesa Throwden, Lateline.