Almost 9 million Australians experience mental illness, and Aussies are among the highest users of mental health apps in the world.

"There are thousands of them," said Piers Gooding, a senior research fellow at Melbourne Law School.

"Some might just be giving you instructions, while others might just be having AI chats involved, and others might connect you to therapists and counsellors in an Uber-style arrangement."

Celebrity endorsements from names like Justin Bieber, Harry Styles, and Ariana Grande also increase their appeal, but that hasn't left professionals convinced.

"The developers will say things like this is evidence-based, it's clinically proven," said Dr Lisa Parker, Senior Health Lecturer.

"Disclaimer, this should not be regarded as medical advice."

Mental health apps are potentially making matters worse.

"There's a bit of a hidden message that worries me," said Dr Parker.

"And the message is that we should be happy all of the time.

You know, actually, ups and downs are normal; they're a normal part of life, and to suggest otherwise, I think, can be quite harmful ."

There are also privacy concerns.

"They'll have your browsing history, they'll link in with your social media accounts, and they can quite clearly work out who you are," Dr Parker said.

And it's not just hypothetical; with BetterHelp fined $11.6 million in the U.S. for illegally sharing data with third parties.

And while amendments to the Therapeutic Goods Act in 2019 were meant to address these risks, another round of amendments in 2021 excluded mental health apps entirely.