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Houttuynia cordata
CautionMolchschwanz · (Houttuynia cordata)
Lizard-tail family (Saururaceae)
Description
A low, runner-forming groundcover from East and Southeast Asia, fish mint carries heart-shaped leaves that give off a distinctly fishy smell when bruised — the work of the aldehyde decanoyl acetaldehyde. In Vietnam and in Yunnan in southwestern China, the fresh leaves and rhizomes are an everyday salad and seasoning herb. Traditional Chinese medicine knows the plant as Yu Xing Cao and regards it as lung-clearing: an infusion of the dried aerial parts is used for cough and upper respiratory complaints, a strong decoction for fever, and folk practice also treats it as a diuretic. Fresh crushed leaves are laid on inflamed skin. Alongside decanoyl acetaldehyde, the flavonoids quercetin and isoquercitrin are considered the active constituents; controlled human studies are largely absent. One distinction matters: tea and tincture are not the same as the injectable preparations that have been restricted in China after severe allergic reactions.
🌿 Risk of confusion — read before wild-harvesting!
Injectable Houttuynia preparations were regulated in China due to severe anaphylactic reactions (including fatalities) — these warnings do NOT apply to herbal tea or oral tinctures, which are considered significantly safer.
Infusion of dried aerial parts (leaves, stems) is used in Traditional Chinese Medicine (TCM) for upper respiratory tract infections, chronic cough, bronchitis, and pneumonia. The herb is considered lung-clearing (清肺 qīng fèi) and expectorant. Clinical evidence is lacking; use is based on millennia of TCM tradition and preliminary pharmacological studies.
Preparation & dosage
Pour 200 ml boiling water over 3–10 g of dried herb, steep for 10 minutes, strain. Drink up to 3 cups daily. Do not use longer than 4 weeks without a break.
- Dry amount
- 3–10 g
- Doses per day
- 3×
In TCM, Houttuynia (Yu Xing Cao / 鱼腥草) is traditionally used for urinary tract infections and to strengthen immune defences. The diuretic effect is empirically supported; antimicrobial constituents (decanoyl acetaldehyde, quercetin) are discussed as the mechanism.
Preparation & dosage
Steep 5–15 g dried herb in 250 ml hot water for 10 minutes. Drink 2 cups daily with adequate fluid intake.
- Dry amount
- 5–15 g
- Doses per day
- 2×
Fresh, crushed leaves are applied in Asian folk medicine to inflamed skin areas, boils, snake bites, and poorly healing wounds. Astringent tannins and antibacterial constituents act as surface disinfectants.
Alcoholic extract from fresh or dried plant parts as immune tonic. In vitro studies demonstrate antiviral activity against HSV through inhibition of the NF-κB pathway; clinical evidence in humans is lacking. Not equivalent to injectable Houttuynia preparations, which have caused severe hypersensitivity reactions.
Preparation & dosage
Ready-made preparation (1:5 tincture, 40% ethanol) as per manufacturer's instructions. Do not self-prepare without phytopharmaceutical experience. Maximum use: 4 weeks.
- Doses per day
- 2×
Fresh leaves and rhizomes are eaten in Southeast Asian and southwestern Chinese cuisines as a salad herb, condiment, and side dish (Vietnam: rau diếp cá; Yunnan: zhé'ěrgēn). The characteristic fishy smell comes from decanoyl acetaldehyde. Consumption is considered digestive and mildly anti-inflammatory.
In Chinese and Vietnamese folk medicine, a strong decoction of the whole plant is used to reduce fever. Antimicrobial flavonoids (quercetin, isoquercitrin) and volatile decanoyl acetaldehyde are regarded as active principles. Not a substitute for medically prescribed therapy in persistent fever.
Preparation & dosage
Simmer 10–30 g fresh or 5–15 g dried plant in 300 ml water for 20 minutes, strain. Drink twice daily. Consult a doctor for fever lasting more than 2 days.
- Dry amount
- 10–30 g
- Doses per day
- 2×
Partial baths and compresses with concentrated Houttuynia infusion are used in folk medicine for eczematous skin conditions, pruritus, and infected skin lesions. The antibacterial and astringent properties are considered effective; controlled studies are lacking.
Injectable Houttuynia preparations were regulated in China due to severe anaphylactic reactions (including fatalities) — these warnings do NOT apply to herbal tea or oral tinctures, which are considered significantly safer. Oral use at recommended doses is considered safe; avoid with known Saururaceae allergy. High doses may exert emmenagogue effects. The characteristic fishy smell of the herb is a quality indicator when purchasing (volatile aldehydes that dissipate quickly).
⏱ Max continuous use: 4 weeks
Emmenagogue properties documented (PFAF); do not use medicinally during pregnancy. Culinary amounts in food are generally considered safe.
No safety data for use during lactation. Avoid medicinal doses as a precaution.
No controlled data for children. Medicinal use not recommended for children under 12 years.
Drug interactions
Immunsuppressiva
Immunomodulatory effects of Houttuynia may theoretically interact with immunosuppressive therapy; no clinical case reports available.
Contraindications
- Known hypersensitivity to Houttuynia cordata or other Saururaceae
- Pregnancy (emmenagogue effect possible)
Harvested part: leaves, rhizome
- Time of day:
- Morning after dew has dried; before full bloom for maximum active compound content.
- Drying:
- Dry herb loosely at 35–40 °C in the shade. Higher temperatures cause loss of volatile constituents (decanoyl acetaldehyde). Well-dried: crackles when crumbled.
- Storage:
- 12 months — Store in airtight glass or metal containers, dark and dry. The characteristic smell should remain faintly detectable.
- Time of day:
- No time-of-day restriction; clean rhizomes immediately after digging.
- Drying:
- Wash rhizomes, cut into pieces and dry at 40–50 °C or use fresh. Fresh rhizomes keep in the refrigerator for max. 1 week.
- Storage:
- 18 months — Store dried rhizome pieces cool, dry, and protected from light; in glass containers.
- Decanoylacetaldehyd (Houttuynin)Essential oilAerial parts
Characteristic lead aroma and active compound; responsible for the fish-like smell. Volatile — largely lost on drying; antibacterial and antifungal in vitro.
- QuercetinFlavonoidLeaf
Dominant flavonoid; antioxidant, antiallergic, and antiviral; inhibits pro-inflammatory mediators in vitro.
- Isoquercitrin (Quercetin-3-glucosid)FlavonoidLeaf
Quercetin glycoside with better water solubility than the aglycone; antimicrobial and anti-inflammatory.
- Quercitrin (Quercetin-3-rhamnosid)FlavonoidAerial parts
Further quercetin glycoside from Houttuynia; antioxidant and immunomodulatory in laboratory studies.
- Aristolactam-AlkaloideAlkaloidAerial parts
Alkaloids described in Planta Medica with anti-inflammatory activity (arachidonic acid metabolism inhibition). Present in low amounts; no nephrotoxicity known as with true aristolochic acids.
- 2-UndecanonEssential oilAerial parts
Volatile ketone in the essential oil; contributes to aroma; antimicrobial activity described in vitro.
- beta-MyrcenEssential oilAerial parts
Monoterpene hydrocarbon in the essential oil; anti-inflammatory and analgesic properties known.
- Kaffeesäure / ChlorogensäurePhenolic acidAerial parts
Hydroxycinnamic acid derivatives; antioxidant and antimicrobial; contributing to total phenolic activity.
- [3]MonographQu W et al. (2010): Chemical Constituents from Houttuynia cordata. Chinese Journal of Natural Medicines. DOI 10.3724/sp.j.1009.2009.00425(accessed: 2026-05-24)
- [4]MonographKurmanbaeva AK et al. (2022): Chemical Compounds of Houttuynia cordata Thunb and Their Specific Pharmacological Activities. Farmacia Kazahstana. DOI 10.53511/pharmkaz.2022.98.37.023(accessed: 2026-05-24)
- [5]MonographZhang QW (2015): Houttuynia cordata Thunb 鱼腥草 (Yuxingcao, Houttuynia). In: Dietary Chinese Herbs. DOI 10.1007/978-3-211-99448-1_71(accessed: 2026-05-24)
- [6]BookPlants For A Future (PFAF): Houttuynia cordata(accessed: 2026-05-24)
- [1]WikipediaHouttuynia cordata — Wikipedia(accessed: 2026-05-24)
Distribution in Europe
🪴 Grow at home
- ☀ Light
- partial shade
- 💧 Water
- daily
- 🌱 Soil
- Moist to wet, loamy
- 🪴 Pot
- 20 cm
- ⭐ Difficulty
- ★★☆ intermediate
- 🐾 Pets
- non-toxic — not externally verified
Tips:
- Needs CONSTANTLY moist soil — saucer with water.
- Spreads aggressively — keep in pot, don't plant in garden.
- Strong flavour ("fish mint") — good for Asian cooking.
Care tips are general indoor-gardening recommendations, not scientific sources.