Heartleaf Skincare: What the Houttuynia Cordata Research Shows

Heartleaf is Houttuynia cordata, an edible East Asian plant with a fishy smell and a long record in folk medicine. Heartleaf skincare sells it as calming and good for breakout-prone skin. Lab and animal studies support parts of that story. We found only one controlled trial on human skin, and it tested heartleaf in a blend of four herbs. Below: what the plant contains, what each kind of study shows, where the marketing runs ahead, and how to try it sensibly.

What is heartleaf?

Heartleaf is a herb with heart-shaped leaves, which is where the species name cordata comes from. A 2022 review describes it as a rhizomatous perennial found in China, Japan, Korea and Southwest Asia. In Chinese medicine it is called Yu-Xing-Cao, and the same review notes its fishy smell.

It is food as well as medicine. A 2024 review calls it a medicine food homology plant, used in fermented beverages, nutraceuticals, feed and cosmetics. Its Japanese name is dokudami, and across Asia it has been used as a folk medicine for diabetes, obesity, cough, fever and skin diseases.

The skin use is concrete. An interview survey in Japan found that a poultice made from fresh leaves was most often used for pus-filled skin conditions such as boils. It is a tradition, not a trial.

What is in it?

The same 2024 review lists the main constituents as volatile oils, flavonoids, organic acids and alkaloids. Which of these ends up in a product depends on the part of the plant, the solvent and the process.

Group	Examples	What the research on them mostly is
Flavonoids	Quercitrin, hyperoside, rutin, isoquercitrin	Cell studies on UV stress and inflammation
Volatile oil	n-Decanoic acid, beta-myrcene, 2-undecanone	Lab tests against skin microbes
Polysaccharides	Complex plant sugars	Mouse models of eczema

The flavonoid names come from the 2022 review's table of constituents. The oil components come from a 2025 analysis that found n-decanoic acid at about 46 percent, beta-myrcene at about 14 percent and 2-undecanone at about 11 percent. Labels rarely say which fraction a product uses, or how much.

What lab studies show

Most of the evidence is cells in a dish. It is useful for mechanism. It cannot tell you what a toner does on a face.

• UV stress. In human keratinocytes exposed to UVB, an extract fraction protected cells from UV-induced death and lowered inflammatory signals such as IL-6 and IL-8. Quercitrin and hyperoside were the main polyphenols and carried much of the effect. This was in vitro work.
• Barrier genes. In cultured keratinocytes, an extract raised the gene expression of filaggrin, a protein the skin barrier depends on, and switched on an antioxidant enzyme pathway. Also in vitro.
• Aging claims. In human dermal fibroblasts exposed to UVB, a hyperoside-rich fraction raised collagen type I output and lowered MMP-1, an enzyme that breaks collagen down. In vitro again, and fibroblasts in a dish sit under no outer skin layer.
• Bacteria. An extract of the traditional poultice showed antibacterial and anti-biofilm activity against MRSA, and it damped inflammatory signals in keratinocytes. The essential oil inhibited the growth of Cutibacterium acnes and Staphylococcus aureus, two bacteria tied to acne and skin infection. Both were lab tests.

Read these as reasons to study the plant, not as results. A cell culture has no outer skin layer, no oil and no daily wash. Our look at centella, another plant sold as calming, found the same gap between the dish and the face.

Is fermented heartleaf different?

Some K-beauty products use fermented heartleaf. Fermenting a plant with yeast or fungi can change what the extract contains, and two lab studies looked at this.

In the first, heartleaf fermented with the fungus Aureobasidium pullulans had 5.4 times the total polyphenols of a plain water extract. It also lowered inflammatory proteins such as COX-2 in keratinocytes stressed with UVA or hydrogen peroxide. The second used a different yeast. Its fermented broth showed higher antioxidant activity than the unfermented broth, and it damped inflammatory signals in cells exposed to bacterial lipopolysaccharide. Two of its authors were employed by a company.

Both were cell studies. Neither compared fermented and plain heartleaf on human skin. On a label, "fermented" describes a process, not a proven upgrade.

What animal studies show

Mouse studies go one step further, since they involve living skin. Two are typical.

• Mice were given an eczema-like condition with a vitamin D analog. Heartleaf polysaccharides reduced skin thickening, lesions and mast cell buildup, and brought barrier proteins back up.
• In hairless mice with eczema-like lesions induced by a chemical allergen, a water extract lowered IgE and interleukin 4, two markers of allergic inflammation. Packaging the extract in lipid carriers helped more of it cross skin in a lab test and made it more effective in the mice.

These are induced models. The disease is created on purpose, and mouse skin differs from human skin in thickness and structure. Results in mice do not always carry over to people.

What human studies show

Here the record gets short. We searched PubMed for trials of topical heartleaf on human skin and found one controlled trial.

It came from the dermatology department of Seoul National University. Sixty people with mild to moderate acne were randomized to a herbal extract product or a vehicle for 8 weeks. The product combined mangosteen, Lithospermum, Tribulus and heartleaf. Inflammatory and non-inflammatory lesion counts fell significantly in the herbal group. Skin biopsies showed larger drops in IL-1 alpha, IL-8 and keratin 16 than in the vehicle group, and there were no serious adverse events.

That is a real result, with two limits. It tested a blend, so heartleaf's own share is unknown. And sixty people over eight weeks is a small, short trial. A trial that settles the question would test heartleaf alone against the same base formula, on the claim being made, for at least that long. Persistent or scarring acne still belongs with a board-certified dermatologist, because prescription options exist.

Heartleaf skincare claims, checked against the evidence

Heartleaf is marketed as calming and suited to oily, breakout-prone skin. Here is how the common claims line up.

• "Calms redness." Only cell and mouse studies point that way. We found no human trial that measured redness.
• "Clears acne." One 8-week trial of a four-herb blend, plus lab work against acne bacteria. No trial of heartleaf alone.
• "Repairs the barrier." Filaggrin genes in cultured cells and barrier proteins in mice. We found no human measurement of water loss or barrier function.
• "Controls oil." We found no study of heartleaf and sebum.
• "Protects from UV." Cell studies only. Heartleaf is not a sunscreen and does not replace one.

None of this makes heartleaf useless. It can be a reasonable passenger in a toner. It is just not the proven active the marketing implies. How toners and essences differ as formats is covered in toner vs essence.

The label can tell you a little about how much is inside. US rules require ingredients in descending order of predominance, with those at 1 percent or less allowed in any order after the rest. A front-of-pack percentage rarely says how concentrated the extract itself was. Our ingredient list guide shows how to find the 1 percent line.

Is heartleaf safe? How to try it sensibly

We found no published case reports of contact allergy to heartleaf in PubMed. That is not proof of safety. It may simply mean few reactions have been written up.

Injected heartleaf is a different story. A 2010 systematic review of Houttuynia injection, an herbal medicine, collected 1,232 reported adverse reactions, with anaphylactic shock the most common of the gravest ones. An injection is a different route and formulation from a toner, so this says little about skin products.

The plant's other safety questions mostly concern eating it. The 2022 review notes reports that it contains aristolactams and aristolochic acid, which are linked to kidney damage and cancer, and calls the toxicity data insufficient. We found nothing showing that this applies to a product used on skin. It is still a reason to treat "edible" and "tested" as different words.

• Patch test a new product for several days first. Our patch test guide covers where and how long.
• Add one new product at a time, so you know what caused any reaction.
• If your skin reacts easily, read the full ingredient list, not just the name on the front.
• Persistent redness can be rosacea, and our sensitive skin guide covers when redness is something else.

Frequently asked questions

Is heartleaf the same as Houttuynia cordata?

Yes. Heartleaf is the skincare name for Houttuynia cordata, named for its heart-shaped leaves. It is called dokudami in Japan and Yu-Xing-Cao in Chinese medicine. On an ingredient list, look for the Latin name.

Does heartleaf help acne?

Possibly, but the human evidence is thin. In one 8-week randomized trial in 60 people, acne lesion counts fell with a blend of four herbal extracts that included heartleaf. Lab studies show activity against acne bacteria. No trial has tested heartleaf on its own, so see a dermatologist for acne that persists or scars.

Is heartleaf good for sensitive skin?

It has a gentle reputation, and we found no published case reports of contact allergy from heartleaf skin products. Allergic reactions have been reported with injected heartleaf medicine, a very different route. The calming evidence comes from cells and mice, not from human trials. Patch test first and add one new product at a time.

Why do some heartleaf products smell fishy?

The plant itself has a fishy smell, which is reflected in its Chinese name. Its volatile oil is rich in compounds such as n-decanoic acid and 2-undecanone. How much smell survives depends on the extract and the formula.

Is fermented heartleaf better than plain heartleaf?

Not on current evidence. Two cell studies found fermented extracts richer in polyphenols or stronger as antioxidants than plain ones, and both damped inflammatory signals in stressed cells. No study has compared the two on human skin. Treat "fermented" as a description of how the extract was made.

Is heartleaf better than centella?

Not on current evidence. Centella has several small randomized trials on human skin, including wrinkle and hydration studies. Heartleaf has one blended acne trial. Both are plant extracts sold as calming, and both have more lab data than human data.