More than 20 people were treated in hospitals after overdosing on drugs, Melbourne Magistrates Court heard on Monday, and the fatalities included one man who overdosed at a home in Elwood.

Five people overdosed at Revolver Upstairs in Chapel Street, Prahran, but none of those wasfatal. Police are now investigating potential links to the bad batch of drugs.

As the probe continued, French national Sebastien Verger-Giambelluco fronted court on Monday following his arrest in connection to one of the overdoses at Revolver Upstairs.

A woman in her early 20s remains in hospital following the overdose.

Mr Verger-Giambelluco is charged with trafficking and possessing a drug of dependence and dealing with the suspected proceeds of crime.

He was granted bail when a magistrate cast doubt over the strength of the case against him, as it was unclear whether the woman took the drugs he allegedly sold or whether she also took other drugs.

Magistrate Andrew Capell said while there was the potential for "enormous" harm in selling drugs, the allegation Mr Verger-Giambelluco sold drugs that caused the woman's overdose was "suggestive only".

"The evidence of that is tenuous at best at the moment," Mr Capell said.

Detective Senior Constable Simon McClosky told the court the woman's friend bought drugs from Mr Verger-Giambelluco, and that the friend pointed the accused man out to security after the woman's suspected overdose.

Detective Senior Constable McLosky told the court more than 20 people had overdosed at the weekend before being treated at The Alfred and Royal Melbourne hospitals.

Three of those overdoses were fatal, he said.

Mr Verger-Giambelluco, 30, was later found in possession of 14 capsules and $1500 cash, and a police search of his Melbourne apartment later revealed a five-gram "rock" of what police believe is MDMA, enough to produce 50 ecstasy pills.

Forensic testing of the capsules and the suspected drugs found in his apartment is yet to be done, the court heard.

Detective Senior Constable McClosky said police opposed bail over fears Mr Verger-Giambelluco would sell drugs if released, and over concerns of the "toxic quality that has already been sold".

Defence counsel Will Collins-Putland said Mr Verger-Giambelluco was in Australia on a working holiday visa and was working as a waiter at three restaurants in Carlton and that he had surrendered his passport.

Mr Capell granted bail on conditions the accused man report to police three times a week, not leave Victoria and stay out of licensed premises, other than for work.

The magistrate found that keeping Mr Verger-Giambelluco in custody would probably exceed the penalty imposed if he was found guilty of possessing a drug of dependence.

Mr Verger-Giambelluco is due to return to court on February 13.