Now, the NSW Illawarra region woman lives with chronic arthritis in her back, shoulders and hips and described the pain over the years as "absolutely crucifying".

"I couldn't sleep, I was restricted in housework, I was holding on to things trying to keep myself up," Trish said.

Desperate for relief, Trish said she tried "everything known to man". When conventional medicine wasn't cutting it, she thought she would try cannabis from Nimbin.

"I stopped doing that because it's illegal," she said.

After a shock bowel cancer diagnosis, Trish sought a medicinal cannabis prescription as a "last ditch" effort.

"I thought I would try get it legally," she said. "I went to the doctor and got clearance from the government for my prescription."

In nine months, it changed her life, giving her freedoms she never thought she would get back.

"I've got arthritis through all of my joints basically," she said.

"But I can actually use them now ... I couldn't before.

"I can get around, drive my car ... I was able to go shopping for the first time in a long time with my daughter in Shellharbour."

Illawarra region mother-of-two Brooke Swan shares a similar story.

When she was just 18, Brooke was taking 23 different types of medications per day, including opioids and heavy pain medications, to manage chronic back pain after a childhood injury.

"I also have Tourette Syndrome and mental health disorders, so I was on medication for that too," the now-29-year-old said.

"But despite the amount I was taking, I was still always in pain. They upped it ... but being on certain medications for such a long time, it stopped working.

"I was pretty much at my wits end with it all, then my doctor said to try the (cannabis) oil."

She was taking 11 tablets per day for pain and struggling with side effects like weight gain But things changed when she started taking the oil a year ago.

"It pretty much did the same thing as the pain medication was doing, but for longer and no side effects," Brooke said.

"I started weaning off my medication one after the other and I was still fine.

"I went from 23 medications to nothing. That's a complete life-changer."

Dr Romesh Sarvanandan, who opened the region's second cannabis clinic at Warrawong General Practice, in NSW's Illawarra, said he has seen a biggest demand for prescriptions over the last year.

"Ninety per cent of my patients are elderly with really bad chronic pain, the younger patients mostly have mental health conditions like severe depression or PTSD," Dr Savanandan said.

But the drug is costly, he said, as its billed privately.

IN OTHER NEWS:

Trish and Brooke are prescribed two medicinal cannabis oils - known as cannabidiol - one for the day time, and a slightly higher dose for the night time.

Trish, who is on an age pension, is forced to be "frugal" so she can afford her medicine.

"For one tiny 50ml bottle it's $260," she said. "It costs me $210 for the other one. I have 0.9ml at night, and I have 0.5ml in the day time.

"It's horrendously expensive."

In April last year, medicinal cannabis was added onto the Pharmaceutical Benefits Scheme (PBS) for the first time, but was only made accessible to Australians living with a rare form of epilepsy - Dravet syndrome.

Australia's medicines regulator, the Therapeutic Goods Administration, said while there were few clinical trials using medicinal cannabis, the evidence to support its use in the treatment of certain childhood epilepsies is the strongest.

But Trish wants to see it expanded to other conditions so access can be improved.

"Others on an age pension who could really do with it can't have it, because they can't afford it," she said. "It just doesn't seem fair."

The Department of Health and Aged Care said in a statement to the Mercury there are no current applications seeking to expand the PBS listing for medicinal cannabis.

It added that subsidies can only be provided if independent experts have examined clinical and other evidence the proposed treatment is safe and cost effective compared to other treatments.

Another downside, Trish said, is that she doesn't drive when she takes the oil. Not because she is impaired by it, but because of the laws surrounding drug driving.

"I don't have it on the days I drive, even though I don't feel any different at all," she said.

"The only thing I do feel is a bit of pain relief."

Brooke's doctor provided her with a letter saying she has a prescription for the medication to show officers if she was ever pulled over, but she still avoids driving.

"Even the chemist who made the oil for me explained that you can drive, but at the end of the day, they still have the ability to charge you," she said.

Brooke said she would happily take an annual driver's test to prove she isn't impaired by the medicine.

Of the hundreds of active molecules in the cannabis plant, 9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are the most abundant.

THC is responsible for the intoxicating effects of cannabis, and is the stuff that gets you "high" whereas CBD is non-intoxicating.

Most medicinal cannabis products contain one or the other, or both, but Trish and Brooke's oil is CBD dominant.

The NSW Upper House recently voted down a bill that proposed to provide medicinal cannabis patients with a defence against drug driving charges if they were not impaired and had taken their medicine as prescribed.

The bill was introduced by Greens MP Cate Faehrmann last year, but was defeated 29 votes to six last week.

"Roadside drug tests can detect minuscule traces of THC in the system of a person who has consumed cannabis long after any effects have worn off," she said.

"Our road laws should have been reformed to reflect this when medicinal cannabis was legalised five years ago.

"Until our road laws are changed, medicinal cannabis users will continue to face discrimination ... it was very disappointing that government speakers to the bill conflated illicit cannabis with legal medicinal cannabis use."

The drug law reform spokesperson said her party would continue to bring the bill back in the next term of parliament.