Australia's biggest online doctor-booking service HealthEngine has announced "major changes" to how it does business following revelations it shared users' medical information with personal injury law firms and other third parties.

Key points: HealthEngine has promised "major changes" after coming under fire from GPs, patients

HealthEngine has promised "major changes" after coming under fire from GPs, patients Health app boasted to advertisers it could tailor advertising to patients' symptoms

Health app boasted to advertisers it could tailor advertising to patients' symptoms Start-up says it will now stop third-party referrals

Last week, the ABC revealed the company had funnelled hundreds of users' health data to lawyers, and boasted to advertisers it could target users with marketing based on their symptoms and medical conditions.

Health Minister Greg Hunt has ordered the Information Commissioner to investigate the company and asked the Digital Health Agency to conduct an "urgent review" of its relationship with HealthEngine.

That came in the wake of complaints from users around Australia who said they were contacted by law firms after using the HealthEngine app, encouraging them to pursue personal or workplace injury claims.

None of the app users the ABC spoke to said they were aware their information would be distributed to third parties.

The Perth-based company, which is part owned by Telstra and SevenWest Media, has maintained it has only ever passed on personal medical information with "express consent" of users.

But now HealthEngine has announced it will stop sharing users' data and will remove advertising from its website.

HealthEngine CEO Marcus Tan had agreed to a pre-recorded radio interview with the ABC to discuss the changes, but later withdrew.

He said in a statement the changes aimed to rebuild trust in the company.

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"Over the past few weeks, a spotlight has been shone on HealthEngine and encouraged us to think about how we can do things better," Dr Tan said.

"By making these changes I am confident we will improve the user experience on HealthEngine and provide even more value for customers."

Dr Tan insisted HealthEngine's relationship with third parties only ever accounted for a portion of its broader business model.

CEO Dr Marcus Tan said HealthEngine will undertake "major changes." ( Supplied: HealthEngine )

"Third party referral was a part of our business model, not the entirety," he said.

"Our core business remains centred around [sic] connecting patients and practitioners and helping Australians access health care more easily. This will not change, and will enable us to continue to be successful."

IT analyst Justin Warren believes HealthEngine was left with little choice but to make the changes after facing a backlash from users and doctors.

"They have been adamant that they've done nothing wrong, and I can't see why they would have changed their business model unless this reaction was starting to affect that business model," he said.

The announcement comes as HealthEngine faces scrutiny from the medical profession over its handling of patients' sensitive medical information.

The ABC has spoken to doctors around the country who have cancelled their HealthEngine subscriptions in the wake of last week's revelations.

The Australian Medical Association last week backed the Health Minister's decision to order the Privacy Commission investigation.

"We look forward to seeing the [Information Commissioner's] report on HealthEngine and we will work closely with the minister and the Government to ensure that patient privacy is protected," AMA president Tony Bartone said.

"There is also the serious matter of the potential of third parties to profit from having access to confidential and private patient information."

HealthEngine's relationship with third parties was laid bare in secret documents obtained by the ABC that showed plaintiff law firm Slater and Gordon had a referral relationship with the service last year.

Under the pilot program, HealthEngine was passing on a daily list of prospective clients to the firm, based on their personal medical information.

HealthEngine passed on details of an average of 200 users a month to Slater and Gordon between March and August last year.

Slater and Gordon has declined to comment about the relationship.

HealthEngine asks users to include details of their symptoms and medical conditions, including whether they have suffered a workplace injury or been in a traffic accident, as part of the process for booking appointments with GPs, dentists, physiotherapists, optometrists, and other medical practitioners.

Under the changes to its business model, HealthEngine will also permanently remove reviews of clinics from its website, following a Fairfax investigation that revealed the company had been tampering with negative patient reviews to make them appear positive.

It also plans to set up an advisory group to work with health providers, consumer groups and regulators to, "ensure our future products and services are informed by consulting more widely".