Michael Douglas left Sharon Stone with a rash after filming a sex scene for Basic Instinct.

The Hollywood legend felt "terrible" that his stubble was "scratching" his co-star and caused Sharon's upper thighs to be "completely red and chafed".

Michael, now 82, reflected on the scene from the 1992 erotic thriller, which took five days to film and saw the pair's characters, Detective Nick Curran and Catherine Tramell romp in bed, in his new memoir, One Helluva Ride.

He wrote: "Sharon and I had vowed not to use body doubles.

"During the scene, Sharon started out wearing a patch over her crotch, a minimal gesture towards modesty. But she eventually decided to forgo it, saying, 'Let's stop pretending. I'm nude, we all know it. Let's go.'"

Sharon, now 68, made it known that Michael's stubble was hurting her.

He penned: "Despite what the finished film looks like, I can assure you that Sharon and I were never actually intimate in this scene.

"I did, however, have to get my face close to some rather delicate areas. At one point my character was performing oral sex on her, and it had to look real.

"After a couple of takes, Sharon said, 'Please go easy. Your stubble is really scratching me!'"

Michael saw that her upper thighs were "completely red and chafed" and he felt "horrible" about what had happened.

It is not the only Basic Instinct revelation he makes in One Helluva Ride.

Michael also confirmed he had a secret romance with co-star Jeanne Tripplehorn while he was separated from his then-wife Diandra Luker.

And he recalled that all the speculation about him and Sharon meant no one noticed what was happening with Jeanne.

Michael wrote: "They were so focused on a possible relationship between Sharon and me, they missed the real relationship happening between me and Jeanne."

He noted that the pair "took great paints to hide" their romance "from the cast and crew".

Michael added: "[We] spent so many hours together, talking, really getting to know each other, enjoying each other's company away from the set and everything else in the world."

Elsewhere in the book, the Fatal Attraction alum admitted he "fell very hard for Jeanne despite our nearly twenty-year age difference".

He continued: "I was crazy about her. But I was also just self-aware enough to know that the worst thing I could do at that moment after nearly twenty years of marriage was jump right into another serious relationship.

"My relationship with Jeanne lasted through production, then we went our separate ways. But I will always think of her as an amazing actress and a truly terrific woman that I was very fortunate to spend time with."

Meanwhile, Michael has confirmed he made sure Jeanne, 63, was happy for him to reveal their romance in his book, given the time that's passed, and her 26-year marriage to her 66-year-old husband, actor Leland Orser.

He told PEOPLE magazine: "It's been a long time, but I called her up and asked for her permission. That's her business. She said yes."

Michael's fling with Jeanne isn't the only relationship he opened up about in the book.

He also told the story of how he and Kathleen Turner, now 72, fell for each other in secret during filming for 1984's Romancing the Stone.

Kathleen has given her thoughts on the matter, telling People in a statement: "Good heavens, what a fuss about something 40 years ago! I love Michael, and I look forward to enjoying the book."