A young dental nurse claims a popular post-gym energy drink caused her to test positive for methamphetamine during a police roadside drug test.

The Sydney woman has revealed how she was left sobbing in a police testing van after she said she was arrested for testing positive to the illicit drug.

She said her nightmare ordeal began as she made her way home from a gym workout while drinking a $4.90 can of OxyShred.

The caffeine-based drink is touted by manufacturer EHPlabs as a 'thermogenic fat burner, designed to increase metabolic rate, boost energy, and aid in fat loss'.

The woman said she had 'skolled' the last of her can of Kiwi Strawberry OxyShred while driving when she was pulled over for the random test the day after Anzac Day.

She said the police officers first carried out a breath test with her before then conducting the roadside drug test.

But as she patiently waited for the result, she was stunned when they returned. 

'He comes over to the car, and he goes, "You're under arrest, you've tested positive to meth",' she revealed. 'I've never done meth in my life, never have, never will.

'I thought he was having a laugh with me, so I said, "sorry, what"?'

The gym-goer burst into tears as she was led into the testing van for further swabs that would later be sent to a laboratory.

'And I'm, like, dying at this point. I'm, like, freaking out. I start crying,' she said.

Traffic law legal expert Karen Stanley said the roadside saliva test, otherwise known as a 'lick test', is only an initial screening tool.

But if motorists return a positive result, it gives police the power to carry out further testing.

This often involves a second saliva sample taken inside a mobile testing unit, which is then sent to a laboratory for detailed analysis.

'Those lick tests are known to be wildly inaccurate,' Ms Stanley told the Daily Mail.

'I'm hearing about it all the time. You dont have to go with police for the second test, but there would be charges if you refused.'

In most Australian states, drivers are not formally charged until the lab results confirm the presence of an illicit substance.

The woman claimed she repeatedly told officers there was no way she could have taken methamphetamine.

'In my head, I'm like, excuse me, sir, I didn't even go out on Anzac Day,' she said. 'How can I test positive to meth?'

She said she asked the officer how common false positives were during roadside testing, and said he told her they were rare, with a 94 per cent accuracy.

'He was quite rude,' she added. 'They were treating me like I was the meth addict.'

Ms Stanley said false positives can occur when legal substances such as medication or ingredients trigger a reaction similar to an illicit drug.

'Lots of things can give you a false positive,' she said.

'I don't know if that drink did it but the tests are not that accurate and do regularly give that result. People can get an immediate disqualification from that.

'Results from the second test can take days or weeks to come back, and while their licence should be reinstated when that happens, sometimes it is not.

'Then people have no choice but to go and see a lawyer and pay $3,000 to go to court to sort it out.

'I'm often hearing about how this is a problem and I have read studies on it too.'

The distraught woman asked if she was allowed to drive home and was subsequently given a third test by police, which came back negative, and she was cleared to leave.

But Ms Stanley says things could have turned out a lot worse for her.

'That's the police going over and above what they have to do,' she explained.

'People lose their licence this way. Imagine if you were a truck driver or something and that's your job and your livelihood gone.'

The dental nurse later asked ChatGPT what may have triggered the false positive by listing everything she had consumed that day including her pre-workout supplement, water and the can of OxyShred.

'[The AI] said the ingredients in the OxyShred - something to do with the bitter orange extract and something else in it - can give off a false positive in a random drug test,' she said in a video posted on social media.

She ended the clip with a warning to fellow gym-goers and energy drink fans: 'If you're drinking OxyShred and get pulled over for a random test, you might test positive to meth.'

The video has since racked up more than two million views with hundreds of people weighing in on the issue in the comment section.

'This happened to me, never touched cocaine and mine came up positive for that,' said one.

'As a FIFO worker, the first thing nurses ask before being tested is if we have had a pre-workout or supplement because it comes up,' added a second.

'The exact same thing happened to my partner,' said another. 'He was gobsmacked when he tested positive - he's never touched drugs and it was an energy drink.'

NSW Police declined to comment on the accuracy of roadside drug tests. Daily Mail have contacted Oxyshred for comment.