Author and journalist Susan Braudy said Douglas's alleged treatment left her feeling "humiliated".
Her claims include that he performed a sex act in front of her.
The Hollywood star responded by saying: "This is a complete lie, fabrication, no truth in it whatsoever."
His statement came 10 days before Braudy's allegations were published in The Hollywood Reporter.
Douglas explained he "felt the need to get ahead" of the situation and share his concerns about the "nightmare" scenario.
'More powerful'