A drug warning has been issued after a teenage boy died and two men became seriously ill after taking what is believed to be a synthetic form of cannabis.

The body of 17-year-old Dean Shield was found in a reserve at Rutherford in the Hunter Valley about 8:00pm (AEDT) on Saturday.

Police were later told the teenager had consumed a synthetic form of cannabis known as 'Chronic' in the hours before he died.

Yesterday police were told two men, both aged 22, had fallen ill in the nearby suburb of Telarah after taking the same substance but their symptoms were not believed to be life-threatening.

Both are now receiving medical treatment.

Police Superintendent Craig Jackson described the death of the teen as a tragedy.

"This is a 17-year-old boy who has died under very sad circumstances," he said.

Police have seized a quantity of the drug from a house at Rutherford and are still awaiting the results of a post-mortem examination.

Officers also said they searched a business at Rutherford.

Police are warning anyone considering experimenting with illicit or synthetic drugs not to do so, regardless of how the drugs are branded.

They have issued a warning against the use of any synthetic or illicit drugs, saying it was a "gamble with your life that's not worth taking".

A sign posted on a bridge not far from where 17-year-old Dean Shield's body was found at Rutherford. ( Facebook: Bree Gillespie )

Research showed that one in 100 Australians have taken the risk.

Professor Jan Copeland from the National Drug and Alcohol Research Centre said young people were often sucked in by the packaging.

"Typically it's either young people who are experimenting, who thought the drug may have been legal or even safe because of the way it's packaged, through to, most commonly, people who wish to avoid being detected for their drug use in the workplace," she said.

Three years ago, Commonwealth legislation outlawed synthetic cannabis.

However, because the formula was constantly changing, not all varieties were picked up by drug tests.

Samaritans Foundation project development facilitator Helen Fielder-Gill said synthetic cannabis was easy to come by.

"Anecdotally, what we hear from people that we work with is that it's gradually coming back," she said.

"So, after it being legal and being made illegal we had a bit of a lull and that was great, and gradually that's increased."

Local MP urges parents to warn children

Labor MP for Maitland Jenny Aitchison said she was shocked to hear about the teenager's death.

She urged local parents to talk to their children about the dangers of taking drugs.

"I hope that everyone takes the opportunity to speak to the young people in their care, or that they're aware of, and just say this is something you need to be aware of," she said.

"Don't ever trust anyone that any drug is going to be OK, because you just can't take that risk. It's not worth it."

Ms Aitchison said synthetic drugs could come in professional-looking packaging but that should not make anyone complacent.

"I think that's a problem for a lot of our young people. They just assume because it looks professionally packaged that it must be something that's available, or somebody has checked it.

"People haven't checked it. These people are basically profiting off young people's ignorance and that's something we really need to address as a community."

Professor Richard Mattick from the National Drug and Alcohol Research Centre at the University of NSW said while he does not know the specifics of the drug in question, the ingredients used in such drugs were a problem internationally.

"To a certain extent because they're all slightly different we don't know exactly what's in them," he said.