Bail has been refused for a Chinese tourist over a botched breast surgery procedure she allegedly carried out on the manager of a Sydney beauty clinic.

Jean Huang, 35, remains unconscious after undergoing a procedure at the Medi Beauty Clinic in inner Sydney.

Police allege that on Wednesday afternoon, at the clinic Ms Huang manages, 33-year-old Jie Shao administered a local anaesthetic and breast filler, despite having no medical qualifications in Australia.

Ms Huang subsequently went into cardiac arrest and is still in a critical condition in Prince Alfred Hospital.

Shao's bail application was rejected by magistrate Sharon Freund who said police had a strong case against her.

Police told Central Local Court that Shao had a plane ticket to leave Sydney for China today.

"She has made a number of admissions in relation to local anaesthetics and breast fillers," the magistrate said.

Jean Huang, 35, remains unconscious after undergoing a procedure at the Medi Beauty Clinic in inner Sydney. ( ABC News )

It is alleged Shao "administered an anaesthetic" even though she was not a licenced medical practitioner in Australia.

She has been charged with recklessly inflicting grievous bodily harm and using poison to endanger life.

The magistrate rejected assurances from the tourist's legal aid solicitor that she had qualifications from the Canton (Guangdong) Medical University.

"These are very serious charges with a maximum of 10 years in jail," the magistrate said.

"As Ms Shao is a tourist she is clearly a flight risk and risk to the community."

Police said emergency services were called to a salon on Carlton Street, Broadway, at 3:30pm on Wednesday following reports of a medical episode.

The police prosecutor said it was a strong case "with admissions on electronic recordings".