Police are investigating whether the drink at the retreat in Clunes in country Victoria contained mushrooms.

Officers were called about midnight on Sunday and believe the 53-year-old Ringwood North woman became ill after having the drink.

Police on Friday confirmed they were still investigating the woman's death despite an autopsy being unable to find a cause of death.

The retreat describes itself on social media as an alternative and holistic health service.

It advertises multiple services, including facials using "wild foraged plants".

Clunes is about 30km from Ballarat, which has experienced a series of tragic events in 2024.

Three local women, Samantha Murphy, Rebecca Young and Hannah McGuire, have died allegedly at the hands of men in the past two months.

Miner Kurt Hourigan died in a mine collapse in March and the area experienced bushfires over summer.

Less than a year ago, three people died and another was hospitalised for months after allegedly consuming poisonous mushrooms in eastern Victoria.

Don and Gail Patterson, both 70, and Gail's sister Heather Wilkinson, 66, died after eating a meal at the home of Erin Patterson in Leongatha in July 2023.

Ms Wilkinson's husband Ian, who was also at the lunch, spent close to two months in hospital.

Erin Patterson, a mother of two, has been charged with three counts of murder and five of attempted murder.

Australian Associated Press