Lorraine Elwell says her 12-year-old son Hunter was suffering an epileptic seizure every 30 seconds, but that once he started using medicinal cannabis they were halved almost immediately.

Researchers at the University of Sydney are looking for families like Ms Elwell's who have been giving medicinal cannabis to children with epilepsy to help them, as part of a project to learn more about the drug's effectiveness.

Medicinal cannabis is illegal in Australia, but many families have been sourcing it illicitly from backyard manufacturers and administering it to children who suffer from seizures, they say with positive results.

Researchers at the Lambert Initiative at the University of Sydney, in partnership with Epilepsy Action Australia, have launched the Paediatric Epilepsy Lambert Initiative Cannabanoid Analysis (PELICAN) Study.

Ms Elwell said this is the chance for families like hers to tell researchers how cannabis has helped their children and has urged other parents to take part in the study.

"I guess we're teaching the researchers this time which is really different and they're listening to us - that's something."

Professor Iain McGregor said his team was hoping to interview as many families as possible in order to learn about how the medicinal cannabis was helping their children.

"There's two things we want to do with this study," Professor McGregor told the ABC.

"One is to understand the experiences of these families what they're going through.

"We're going to take samples of the oils that they're taking from cannabis plants, bring them back to the laboratory and do an analysis of what they contain."

Parents will have the option to receive individual feedback on the Cannabanoid content of their sample.

Hunter spent more nights in hospital than at home during his first eight years of life, his mother says. ( Supplied: Lorraine Elwell )

Cannabis having 'miraculous effects' on children

Professor McGregor said medicinal cannabis was already having "miraculous effects" on children who suffered from seizures.

"We have these amazing informal clinical trials going on in the community, it's so widely used for such a variety of conditions yet it's all done unofficially ... and there's very little quality control over the cannabanoid products that are being used.

"The PELICAN Study might give us a clue about which cannabanoids are important in treating epilepsy and perhaps help guide governments if they decide the produce products to help these children."

Researchers are interested in talking to families who are currently using medicinal cannabis on their epileptic children, families who have tried to drug and stopped for whatever reason, and those who have never used cannabis-based treatments.

All the interviews would be confidential and the information collected would be de-identified.

Research associate and trial coordinator Anastasia Suraev said many parents have been working out dosage by "trial and error" with great success, so they would be able to provide invaluable information for the study.

"They have so much knowledge about these products, the types of ones to use, what kind of negative side effects or positive side effects they may or may not have, how efficacious they are," she said.

"I think the interesting thing that we might find out is how different cannabanoids seem have different effect for different epilepsy syndromes and different seizures types."

Mother didn't believe results from cannabis use

Ms Elwell's son Hunter suffers from Dravet Syndrome - a severe form of epilepsy that seems to be resistant to conventional medications.

"Our day-to-day life before medicinal cannabis was hospital — we pretty much lived there," Ms Elwell told the ABC.

"We spent more accumulative nights in hospital a year than we spent at home for the first eight years of Hunter's life.

"I'd say at his worst he was having one seizure every 30 seconds."

Hunter's seizures reportedly halved after he started taking medicinal cannabis. ( Supplied: Lorraine Elwell )

Ms Elwell began sourcing medicinal cannabis for her son four years ago and said she noticed a difference "straight away".

"Within 24 hours his seizures had halved, and I honestly thought it was a coincidence," she said.

"I was going, 'no, it's just too quick and too easy'.

"He was still on the same medications, but it seemed the medicinal cannabis had a reaction to all the other drugs and seemed to lower the bad side effects.

"Within a week the seizures had gone from 20 or 30 big ones a day and 100 little ones, to probably four in a week - it was amazing."

Ms Elwell has thrown her support behind the PELICAN Study and urged other parents who have been illicitly sourcing medicinal cannabis to treat to their epileptic children to take part.