Serena Williams (Photo : Getty Images/ANGELA WEISS / AFP)
Former US tennis player Serena Williams attends the CFDA Fashion Awards at the American Museum of Natural History in New York on November 6, 2023.

Serena Williams has shared an unconventional beauty hack.

In a video posted on TikTok Sunday, Williams, 42, revealed that she used breast milk to soothe sunburn under her eyes.

The video showed her shaking a small bottle of breast milk before delicately applying the liquid beneath her eyes with a tissue.

"OK, is this totally weird??? I have to say after a week of using MY breast milk under my eye – it worked!" the tennis legend captioned her TikTok clip, which was reposted by Page Six.

"I’m dying to hear your thoughts. Be nice lol [monkey closing its eyes emoji]," she added.

In the clip, Williams, who recently welcomed her second daughter, Adira River, with husband Alexis Ohanian, detailed her skincare journey and explained why she added breast milk to her routine.

Williams shared that she got a sunburn under her eyes while she was out in the sun with retinol, a skincare product that can heighten sensitivity to the sun, on her face.

The former pro athlete, also a mother to 6-year-old daughter Olympia with Ohanian, said she decided to give breast milk a try because it works for her child.

"They say put breast milk on everything, and I have a lot extra, so I’m gonna try it for a week or so and see how it goes," Williams explained in the video.

While she claimed that the remedy worked, she did not share visual proof in her post.

Williams joins the list of celebrities who have praised the healing properties of breast milk.

In an April interview with Nylon Magazine, singer Halsey shared her experience using breast milk to heal her skin, declaring it the "best skincare ingredient" and claiming that its antioxidants and good fats help "speed up the healing process."

Halsey, who welcomed son Ender in 2021, also highlighted her increased awareness of skincare ingredients after giving birth.

She explained, "When your baby is kissing you or snuggled up against you, you become hyper-cognizant of what’s on your face."