You’ve Seen This Ingredient Before
You’ve probably seen it on your skincare shelf: heartleaf toners, serums, and ampoules that promise calming, soothing skin. Houttuynia cordata is already one of the most familiar calming ingredients in K-beauty, with multiple brands featuring it in toners and serums.
But here’s something most people don’t know: the same ingredient is in foot soaks, too. Why does a calming skincare ingredient show up on a foot soak label?
Over the Wenzday’s foot soak gels list Houttuynia Cordata Extract in their full ingredient disclosure. Its Korean botanical name is yakmoamil (약모밀), and in Korean it’s called 어성초 (魚腥草), meaning “a herb with a distinctive fish-like scent,” after the distinctly pungent smell of its fresh leaves. The English common name heartleaf comes from its heart-shaped leaves. Native to much of East and Southeast Asia, this herb has been part of traditional medicine across Korea, China, Japan, and Vietnam for centuries.
What Traditional Records Say
The Dongui Bogam, Korea’s foundational medical encyclopedia compiled in 1613, records yakmoamil briefly:
性微溫, 味辛, 有毒. 主蠼螋尿瘡.
Slightly warm in nature, pungent in taste, toxic. Primarily used for sores caused by earwig urine poison.
Short as the entry is, it suggests the herb was already associated with skin-related concerns.
Later Chinese materia medica expanded its documented uses considerably. The Bencao Gangmu (本草綱目) includes records of applying the herb’s juice to draw out heat toxins from skin swellings, washing affected areas with a decoction (熏洗, xūn xǐ), and applying crushed leaves to stubborn sores. The Benjing Fengyuan (本經逢原) notes:
近世僅以煎湯薰滌痔瘡，及敷惡瘡白禿
“In recent times it is mostly used as a decoction to wash and fumigate affected areas, or applied to stubborn sores and scalp conditions.”
Across centuries, the pattern is consistent: boil it, crush it, wash with it. Herb meeting skin directly.
Why Modern Skincare Noticed
Modern research has found that heartleaf contains flavonoids including quercetin, and has been exploring their potential for skin calming. Compounds such as decanal, responsible for the herb’s distinctive smell, are being studied for their potential antibacterial activity.
Some studies and tests have reported results related to sebum reduction and skin calming, and interest in the ingredient continues to grow across global skincare conversations. Cosmetics Business named heartleaf as one of the key K-beauty trend ingredients of 2025.
It may look like a new ingredient, but it’s a traditional herb that has been close to skin for centuries. Modern skincare simply rediscovered it.
From Face to Feet: A Honest Look
One thing worth noting clearly: facial skin and foot skin are not the same. The stratum corneum of the plantar (sole) skin is significantly thicker than facial skin, and its barrier structure differs substantially. Drawing a straight line from facial toner studies to foot care benefits would be an overreach.
That said, there are good reasons why heartleaf shows up in a foot soak.
Feet are a dense environment for sweat glands and bacteria. Calluses build up. In spring, temperature swings make sweat patterns irregular, and skin that’s been dry all winter under thick socks starts to crack. The traditional use of heartleaf in external applications and herbal washes (훈세) points toward an approach that aligns naturally with how a foot soak works: warm water, herb, skin contact.
Rather than claiming the same effects as a facial toner, the context is different: traditional external use patterns and modern skin research, taken together, make it easy to understand why heartleaf appears as a foot soak ingredient.
Spring Is the Right Time to Start
After a winter of boots and thick socks, feet meet spring in rough shape. Calluses are visible. Sweat returns. The skin that’s been sealed away is now exposed. Spring is a natural moment to reset your feet for the new season.
A warm foot soak with herbal extracts, heartleaf among them, is a quiet way to welcome the new season and give your feet a moment to breathe again.
Older Than K-Beauty
Heartleaf became globally known through K-beauty, but its use on skin goes back centuries. Boiled, crushed, washed. It was always a topical herb. Modern skincare simply rediscovered it.
That’s why Over the Wenzday’s Foot Healing Day and Foot Relaxing Day naturally include Houttuynia Cordata Extract as part of a 16-herb botanical blend. The ingredient you know from your toner, now reinterpreted beneath your feet.
Curious about the other herbs in Over the Wenzday’s foot soak gels? Read about what ginseng does, licorice root as the great harmonizer, and kudzu root: the deep releaser.
