Yu Xing Cao (鱼腥草): The Fishy-Smelling Herb That Clears Lung Heat
Yu Xing Cao (Houttuynia) is one of the strongest heat-clearing herbs in Chinese medicine, famous for treating Lung abscess and purulent phlegm. Its fresh leaves smell of raw fish — hence the name — but its clinical record for stubborn respiratory infections is serious.
A Herb Named After Its Smell
Yu Xing Cao (鱼腥草), literally “fishy-smelling herb,” is one of the few Chinese herbs whose name is a literal sensory description. Crush a fresh leaf between your fingers and you will immediately understand — a sharp, unmistakable smell of raw fish fills the air. Most of the country finds this unpleasant. The southwest, however, has built an entire food culture around it: in Guizhou and Sichuan, the same plant is called zhe’er gen (折耳根) and is eaten raw in salads, stir-fried with cured meat, and mixed into dipping sauces. It is, depending on where you grew up, either a beloved vegetable or something you cannot bring yourself to swallow.
The Latin name Houttuynia cordata honours the Dutch botanist Maarten Houttuyn. The heart-shaped leaves are why TCM also calls it gou di feng (狗地风) in some regions, though “Yu Xing Cao” is the pharmacy name everyone uses.
What interests me about Yu Xing Cao is the gap between its folk reputation and its serious clinical use. Many heat-clearing herbs in TCM are gentle and theoretical. This one is not. It is one of the strongest naturally antimicrobial herbs in the materia medica, and for certain Lung conditions there is almost nothing better.
The Basics
| Property | Details | |----------|---------| | Chinese name | 鱼腥草 (Yú Xīng Cǎo) | | Pharmaceutical name | Houttuyniae Herba | | Source | Whole plant of Houttuynia cordata | | Nature | Slightly cold | | Flavor | Pungent | | Meridian affinity | Lung | | Dosage | 15–30g fresh; 15–25g dried (decoction) |
What the Old Texts Say
Yu Xing Cao is a relatively late addition to the formal materia medica. It does not appear in the Shennong Bencao Jing (神农本草经) or even the Bencao Gangmu (本草纲目, 1596) as a primary entry. Its first detailed medicinal record is in Zhao Xuemin’s Bencao Gangmu Shiyi (《本草纲目拾遗》, 1765), the supplementary text Li Shizhen’s grandson-era scholar Zhao Xuemin wrote to fill gaps in the original. Zhao recorded it for “heat toxicity, carbuncles, and Lung abscess.”
This late entry tells you something: Yu Xing Cao was a folk herb of the south that entered mainstream TCM through clinical reputation rather than classical prestige. Doctors kept reaching for it because it worked, not because an ancient authority sanctioned it.
How It Works in TCM Terms
The actions are blunt and easy to remember:
- Clears heat and resolves toxicity (清热解毒) — especially in the Lung
- Resolves abscess and expels pus (消痈排脓) — the signature action
- Promotes urination and leaches out damp-heat (利尿通淋) — for urinary tract infections
The pungent flavor and slight coldness mean it disperses and cools without being harshly bitter. It is one of the few heat-clearing herbs that genuinely targets the Lung rather than the Liver or Stomach.
The Lung Abscess Application (肺痈)
This is where Yu Xing Cao earned its reputation. In TCM, fei yong (肺痈, Lung abscess) is a pattern of heat and toxicity festering in the Lung, producing the classic symptoms: cough, chest pain, and — the hallmark — foul-smelling, purulent sputum that looks like rice-gruel or contains blood. Before antibiotics, this described lung abscess, severe bronchiectasis, and cavitating tuberculosis, and the prognosis was grim.
The canonical formula is Wei Jing Tang (苇茎汤), Reed Stem Decoction, from Sun Simiao’s Qian Jin Yao Fang (《千金要方》, 652 CE). Modern clinicians almost always add large doses of Yu Xing Cao to it — typically 30g — because the herb’s pus-resolving action is so reliable. A common saying in Chinese respiratory wards is that for fei yong, “if you can get the pus out, the patient lives,” and Yu Xing Cao is the herb most relied on for that step.
Dr. Jiao Shude (焦树德) noted in Yong Yao Xin De Shi Jiang (《用药心得十讲》) that for stubborn Lung heat cough with thick yellow sputum, he routinely used 25–30g of Yu Xing Cao decocted separately (后下, added near the end) because prolonged boiling destroys the active volatile oil.
Other Uses
Urinary Tract Infections (湿热淋证)
Because it also drains damp-heat through urination, Yu Xing Cao is used for bladder heat causing painful, urgent, frequent urination — what TCM calls re lin (热淋). It is often combined with Che Qian Zi and Mu Tong.
Skin and Intestinal Infections
Externally, the fresh juice or decoction is applied to herpes, boils, and snakebite. Internally it treats bacillary dysentery and certain intestinal infections. The breadth comes from the same underlying mechanism: it kills or suppresses a range of bacteria and some viruses.
Herpes Simplex and Viral Conditions
Modern interest has focused on Yu Xing Cao for viral respiratory infections, and it was briefly a staple in SARS and early COVID-19 supportive formulas in China. The evidence here is weaker than for bacterial Lung conditions, but the herb’s combination of antimicrobial and anti-inflammatory activity makes it a reasonable choice for viral Lung heat patterns.
Why You Should Not Boil It to Death
This is the practical point most people get wrong. Yu Xing Cao’s active compounds — sodium houttuyfonate, methyl-n-nonyl ketone, and decanoyl acetaldehyde — are volatile and heat-sensitive. If you throw 30g into the pot and boil it for an hour with the rest of the formula, you destroy much of the medicine.
The correct method, as Jiao Shude advised, is 后下 (hòu xià): decoct the other herbs first, then add Yu Xing Cao in the last 5–10 minutes. The fishy smell that fills the kitchen when you do this is, paradoxically, the medicine itself escaping into the steam — so the smell that repels you is exactly what you want to preserve.
The Injection Controversy
In the 1970s–2000s, Chinese pharmaceutical companies produced Yu Xing Cao injections (鱼腥草注射液), marketed for infections. Around 2006, reports of severe anaphylactic reactions and several deaths led the State Food and Drug Administration to suspend and heavily restrict injectable Houttuynia products. The lesson, which Chinese medicine itself has always taught, is that a herb’s safety profile depends entirely on its route of administration. The same plant that is gentle and effective as a decoction can be dangerous when purified and injected intravenously. Oral and topical use remain safe and standard.
A Note on Eating It
If you travel to Guizhou or Sichuan, you will encounter fresh zhe’er gen everywhere — cold-tossed with chili, vinegar, and soy sauce. Eating it as food is a genuine, low-dose way to get its heat-clearing benefits. The flavor is the test: if you can get past the fishiness, you may come to love it, as much of the southwest does. If you cannot, the dried decoction with the smell reduced by proper timing is the more medicinal route.
Finally
Yu Xing Cao is a herb that earned its place the hard way — through clinical results rather than classical pedigree. For Lung heat, purulent sputum, and stubborn respiratory infections, few herbs match its directness. And its strange, divisive smell is a useful reminder that in herbal medicine, the part that offends the senses is often the part doing the work.
Related Reading
FAQ
Why is Yu Xing Cao called the 'fishy-smelling herb'?
The fresh leaves and stems of Houttuynia cordata release a strong, distinctly fishy odor when crushed — which is exactly what the Chinese name 鱼腥草 ('fishy-plant') describes. People in southwestern China (Guizhou, Sichuan) actually eat the fresh herb as a cold salad (折耳根, zhe'er gen) and love this smell, while northerners often cannot stand it. When the herb is dried for medicinal use, much of the odor disappears, and stir-frying (炒) reduces it further. The smell comes from methyl-n-nonyl ketone and decanoyl acetaldehyde, the same compounds that give the herb its antimicrobial activity.
What is Yu Xing Cao most used for in Chinese medicine?
Its primary use is clearing Lung heat and resolving toxicity, especially for what TCM calls 肺痈 (fei yong, Lung abscess) — cough with foul-smelling, purulent (pus-like) blood-streaked sputum. It is also widely used for bronchitis, pneumonia, urinary tract infections, and herpes. In modern Chinese hospitals, Houttuynia extracts have been made into injectable preparations, though these were heavily restricted after anaphylaxis reports in 2006, and oral forms (decoction, tablets) remain the standard.
Disclaimer
This content is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before using any herbal preparation.