Everyone makes beauty decisions they regret and reverse. Nicole Kidman, however, made one she says she can’t take back when she altered her natural hair decades ago. And now she has advice for women with the same hair texture.

The Big Little Lies actress used to have curly, strawberry-blond hair, but she straightened and dyed it for years. And in a recent interview with Australia’s  WHO Magazine, she opened up about that pivotal decision. “I really wanted to have that suntanned skin and long blonde hair,” she said. “I wanted to conform and be the Aussie beach girl. And I was never going to be that.” Unfortunately for Nicole, she says she can never reclaim her natural hair, much as she wants to. “I wish I had my curls back,” she added. “I tortured them to death. I always say, ‘Don’t ruin the ringlets!'”

Dr. Francesca Fresco, a dermatologist who specializes in hair health, told Today certain treatments can definitely harm existing hair. “If a woman is straightening her hair… and bleaching it and blow drying it and flat-ironing it, that’s like the royal flush of things that can really damage hair,” she said. She also warned that in extreme cases, chemical-based treatments can cause inflammation, blisters, and crusting that can damage the hair follicles and change the texture of the hair.

Instead, Dr. Fresco speculated a hormonal change may be responsible for Nicole’s hair evolution. “As [curly-haired people] get gray, they tell me that their hair texture changes and they’re not as curly as they used to be,” she explained. “They’re either straighter or they’re just wavy.” (Dr. Nicole Rogers, a Louisiana-based dermatologist, concurred with that assessment. “I’m not saying it’s impossible, but I would be surprised if it’s a result of the chemical treatment,” she said of Nicole’s experience.)

Luckily for the 50-year-old Oscar winner, another regrettable beauty decision of hers was reversible. “I did try Botox, unfortunately,” Nicole told Italy’s La Repubblica in 2013. “But I got out of it, and now I can finally move my face again.” Well, live and learn!