The 70-year-old - who is married to to natural health entrepreneur John Easterling - says she takes the drug every morning, and at regular intervals throughout the day.
'My husband hands me all these herbs every morning and makes me a green algae drink,' she added. 'He grows the plants and makes them into liquid for me. I take drops maybe four to five times a day.'
The Grease star was recently forced to rubbish rumours she had had weeks to live.
A smiley Olivia appeared in a video posted online wishing her fans and followers a happy 2019, before addressing the reports on her health.
"Happy new year everyone, this is Olivia Newton-John and I just wanted to say that the rumours of my death have been greatly exaggerated to quote a very famous quote.
She continues, "I'm doing great and I want to wish all of you the happiest, healthiest 2019 that's possible.
"And thank you all for your wonderful love and support for me and my Olivia Newton-John cancer wellness foundation in Melbourne Australia."
Olivia was diagnosed with breast cancer in 2017 and also has a tumour in the base of her spine.
She has managed to overcome the disease twice.