Nicole Kidman "can't live without" her Philip B Rejuvenating Oil.
The 51-year-old actress is known for her luscious blonde locks when she is on and off camera, and her long-time hair guru, Philip B - whose devoted fans include the 'Big Little Lies' star, Sir Mick Jagger and Matthew McConaughey - has opened up about what products they both use to keep her hair in the best condition possible.
He told W magazine: "The defining moment of my career was when I developed these unique hair care treatments that really delivered - using pure botanicals in precise blends to restore hair's healthy, youthful feel.
"Nicole Kidman credits my Rejuvenating Oil as a hair product she 'can't live without' for red carpet events and my hot oil treatment is how she likes to 'chill out' after long days on 'Big Little Lies'. I've had Robert Redford come right up to me at an event and thank me for my products; I've had Gwyneth Paltrow write to me about my products."
The Hollywood hair expert also recalled when he worked as a hair stylist in Los Angeles and found that a lot of his A-List clients suffered from "damaged" locks because of the constant "heat styling" on sets.
He said: "I was working in a popular Los Angeles salon with a big Hollywood following. I found that a lot of our A-list actresses had very damaged hair from constant heat styling, chemical treatments, and colour changes for their roles.
"It sent me on a mission to find truly effective ways to restore moisture to their hair and rebuild it. I had this intuitive sense that nothing could heal the scalp and help grow healthy hair like the nourishment of botanicals."
And Kidman fans can achieve effortless Hollywood hair by giving their scalp its own gym workout and "brushing" it before applying shampoo.
He added: "Brushing your hair and scalp before each shampoo can work wonders for the condition of your hair. The trick is using the right kind of hairbrush: It needs to be made with natural boar's-hair bristles.
"Why? Because unlike conventional nylon bristles, boar's hair is porous, which makes it able to pick up the natural oils from your scalp and pull them down through the mid-lengths and ends of your hair, where they're needed."