Ashley demonstrated in the video how she smears the clear cream under her eyes and just lets it "sit there."
"I literally do this every night when I go to sleep," she explained.
She also issued a warning that should be taken seriously.
"It burned my under eyes," a viewer admitted.
"Try not to get too close to where your eyelashes touch because that happened to me a couple of times," she replied.
I'm a 58-year-old former model and makeup artist - my little 'tree trunk' trick will make your eyes look wider
The product doesn't just work for under-eye areas.
Many people use it to diminish discoloration or fade dark marks all over their bodies.
"I grew up putting arnica on bruises," one wrote.
"It also helps with arthritis and rosacea!" a TikTok user commented.
"I heard this works for acne scars too, my dermatologist said, " a woman said.
"Yesss this works. I use it on random bruises I get and they go away pretty quickly," another added.
Anti-aging tips and 'superstar' products
Dr. Anatalia Moore is a GP and skin specialist with over 11 years of clinical experience.
She told The U.S. Sun that her goal is to equip patients with the knowledge they need to take control of their skin journey.
She said the fundamental basics of a beauty routine are the same for all ages — it should include an effective cleanser, moisturizer, and SPF.
"Moisturizers are my superstar, even over products containing active ingredients," she said.
“Finding a well-balanced moisturizer that provides the right kind of hydration, replaces natural oils, and seals them in, literally stabilizes your skin.
“This in itself quickly can soften the appearance of fine lines and texture, as often these are worsened by dehydration.
“It also allows the skin the function as it should.
“It then can heal faster, which amongst many things can lead to fewer lines and wrinkles, less flares of dermatitis and rosacea, and shorter-lived, milder breakouts.”