GREASE star Olivia Newton-John is so desperate in her last-ditch battle against incurable stage IV cancer she’s knocking back a bizarre LSD-like potion concocted by a witch doctor in the Amazon jungle!

And now, the magic brew she’s used at the urging of vitamin-mogul hubby John Easterling has left her convinced she will beat the deadly disease, say sources!

After the 71-year-old Physical singer downed “a little cupful” of the plant-based hallucinogen ayahuasca, she was hit with “room-spinning” delusions and nausea.

But shortly after, she says, “my whole body was at peace. I had a feeling of euphoria. I’d been taking antidepressants for six months, but from that day, I stopped.”

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