A central Queensland mother and father have escaped jail time for administering home-grown cannabis oil to their five-year-old son with autism.

Key points: Jamie Blake and Stephanie Mackay produced their own cannabis oil to treat their son

Jamie Blake and Stephanie Mackay produced their own cannabis oil to treat their son Justice Crow told the court there was no evidence Callum was injured by treatment

Justice Crow told the court there was no evidence Callum was injured by treatment University of Sydney researcher says cannabis oil's effects need further study

Jamie Blake and Stephanie Mackay pleaded guilty to several drug-related charges in Supreme Court in Rockhampton on Monday.

One charge, supplying a dangerous drug to a minor, came with a maximum 25-year jail sentence.

But neither had convictions recorded against them and they received a total of $900 in fines.

Outside court with Ms Mackay and their young children, Mr Blake said he was "relieved".

"I get to go back to my family. I'm glad it's all over — I just want to go home," he said.

The court heard the pair started growing cannabis at their home in Calliope, west of Gladstone, sometime after November 2016.

Police raided their house in November 2017 and found three small cannabis plants growing in a cupboard in their garage.

The couple believed their son Callum had autism, although at the time he was on a wait list for formal diagnosis.

The court heard Mr Blake had sought medical advice from a high profile figure in the medicinal marijuana world, Andrew Katelaris, and decided to start growing the plant.

The ABC has seen documents stating Callum was formally diagnosed with autism earlier this year.

'No evidence Callum was injured'

In sentencing the duo, Justice Graeme Crow described the case as "almost unique".

"I accept that there's no evidence that the child Callum was injured," Justice Crow said.

"I accept that you provided the drug to him for medicinal purposes and after receiving medical advice.

"And as (your) counsel have said, your offending comes through altruistic objectives, that is you're trying to care for your child."

Stephanie Mackay and Jamie Blake gave their son Callum cannabis oil to treat autism. ( ABC News: Emilia Terzon )

Outside court, Mr Blake said he believed the cannabis oil had helped Callum with behavioural issues.

"His frustrations levels were near non-existent. He started talking clearer. Socially acceptable," Mr Blake said.

"It worked. What else have I got to say?"

Medical marijuana effects on autism 'unproven'

The Federal Government legalised medicinal cannabis use in 2016 and regulates its prescription through the Therapeutic Goods Administration (TGA).

It can only be prescribed to a patient by a doctor after a clinical assessment.

In Queensland, the state must also oversee the administration of medicinal cannabis, however the need for that is currently being reviewed.

The medicinal benefits of cannabis oil are still being researched. ( Supplied )

The benefits of medicinal marijuana, or cannabinoids, are still being researched by the University of Sydney's Lambert Initiative for Cannabinoid Therapeutics.

Its clinical research officer Anastasia Suraev said not enough research had been done into autism and medicinal marijuana to conclusively prove a benefit.

"The studies that have been done have suggested possible benefits of cannabinoids [in] very low doses — it has shown to improve behavioural symptoms in autism spectrum disorder," she said.

"There's definitely a possible benefit, however it has not been definitively shown in a larger scale, high-quality trial.

"Most of these studies are not at the level of evidence that doctors would need to make clinical decisions to prescribe products like medicinal cannabis to a young child."

She said more research was needed and welcomed a major study into the issue, about to start in Israel.

"Often parents with children who have very severe autism are frustrated with a lack of effective options, so they turn to things like cannabinoids as a last resort," she said.

Royal Australian College of General Practitioners president Dr Harry Nespolon said "the evidence isn't very strong" that medicinal cannabinoids made any difference to people with autism.

But he said it was legal to prescribe it as a last resort, when traditional medications did not work.

"We'd support studies in any disease group. Just because there's no evidence at the moment, that doesn't mean there isn't evidence in the future," he said.

"There's a lot of promising aspects about medicinal cannabinoids and so there needs to be an increase in a number of studies in a variety of areas including autism."

He said any parent who had exhausted other options for the treatment of their autistic children should always consult a medical professional first, and that homegrown marijuana or street marijuana could be dangerous.