Houttuynia (Yuxingcao): A Fine Medicinal Herb for Treating Lung Diseases
Houttuynia (yuxingcao) is a plant well known to the Chinese as both a medicine and a food, and the custom of eating it is widespread across many parts of China. Everyone knows that after a hotpot meal, a cup of houttuynia tea can clear heat and resolve toxicity. Of course, not long ago an online debate flared up over whether houttuynia is toxic. As far as I know, the authoritative literature does not support the claim that houttuynia is poisonous. Certain manufactured products of houttuynia may have safety problems owing to technical issues, but the herb itself has no obvious toxicity.
Authoritative works on Chinese herbal medicine, such as the Zhonghua Bencao (Chinese Materia Medica) and the Zhongyao Da Cidian (Great Dictionary of Chinese Materia Medica), were compiled by pooling the nation's resources and are classics that have stood the test of time. The toxicity of traditional herbs such as aristolochia (madouling) and asarum (xixin) is recorded in detail in these works; the carcinogenic side effects of asarum were already verified back in the 1980s and 1990s, and the accounts of these side effects in the Great Dictionary of Chinese Materia Medica and the Chinese Materia Medica predate today's so-called new discoveries by several decades. Yet neither the Great Dictionary of Chinese Materia Medica nor the Chinese Materia Medica records any toxicity of houttuynia. The Chinese Materia Medica describes its toxicity as follows: "Houttuynia has very low toxicity, and no cases of poisoning have been reported." The Great Dictionary of Chinese Materia Medica is essentially in agreement. Many of the current articles claiming houttuynia is toxic are sensationalist self-media pieces that have always liked to attack Chinese medicine and lack supporting data; I therefore do not accept them.
Houttuynia belongs to the Saururaceae family. It grows wild in damp, shady places or lowlands near water, prefers a warm and humid environment, dreads drought, is mostly cold-resistant, fears strong sunlight, and can overwinter at minus fifteen degrees Celsius; it is a fresh herb that can be gathered in all four seasons. Modern pharmacology has confirmed that houttuynia has antibacterial and antiviral effects and can also enhance the body's immunity; in addition, it has a marked diuretic action.
Traditional Chinese medicine holds that houttuynia mainly enters the lung channel and is also effective for diseases of the bladder and large intestine channels. Animal experiments have confirmed that twenty minutes after entering the body, the drug is distributed most abundantly in the lungs, which is favorable for treating respiratory diseases; it is also distributed in organs such as the heart, liver, and kidney, while its level in the serum is very low. This finding supports the traditional TCM view that houttuynia primarily treats lung-system diseases. Houttuynia is metabolized rapidly in body tissues, and after two hours the drug can no longer be detected in any tissue. The folk experience of using houttuynia as a tea, drunk frequently so that the medicinal effect is sustained, is thus quite reasonable.
Traditional Chinese medicine holds that houttuynia is pungent in flavor and slightly cold in nature, with the main actions of clearing heat and resolving toxicity, expelling pus and dissipating abscesses, and promoting diuresis and relieving stranguria. It is indicated for lung abscess with pus expectoration, phlegm-heat wheezing and cough, throat moth (tonsillitis), dysentery with heat, sores and toxins, and heat stranguria. TCM commonly uses houttuynia to treat the various lung-system diseases caused by lung heat. In the commonly used empirical formulas for respiratory diseases published by the renowned TCM physician Professor Ye Juquan, almost every formula contains houttuynia, and the dosage is invariably large, usually around 30 g of the dried herb.
The Zhongguo Yaoyong Zhiwu Tujian (Illustrated Handbook of Chinese Medicinal Plants) records that houttuynia can "treat syphilis, stranguria with turbid discharge, difficult urination, urethritis, edema and distension, stomach problems, and various suppurative diseases such as cellulitis, otitis media, mastitis, lung abscess, pulmonary tuberculosis, and uterine diseases; it can also serve as an emetic for emergency treatment of poisoning."
In my own experience, whether taken internally or applied externally, houttuynia has a good anti-inflammatory and antibacterial effect. Among respiratory and urinary diseases that TCM classifies as heat-fire syndromes, houttuynia can be used in large doses. If it is convenient for the patient to gather fresh houttuynia, it is best to wash the fresh herb and brew it as a tea, drunk frequently; this can usually resolve the patient's problem within a day or two. TCM holds that houttuynia clears lung heat above, drains damp-heat of the bladder below, and clears damp-heat of the large intestine in the middle—all of which TCM regards as various heat syndromes, while modern medical research confirms that these are inflammatory reactions caused by bacterial or viral infection.
When using houttuynia to treat upper respiratory diseases, throat diseases, and otitis media, one can also crush fresh houttuynia to extract the juice and drip it into the nose or ear. When dripping into the nasal cavity, a few drops may be used; when dripping into the ear canal, one or two drops suffice. This method delivers the active constituents of houttuynia directly to the lesion and takes effect rapidly. Dripping houttuynia juice into the nose can treat chronic sinusitis; combining it with houttuynia tea taken internally gives even better results.
Houttuynia can also be crushed and applied externally. The whole plant is used as medicine. To treat superficial cellulitis, take an appropriate amount of the rhizome, stem, and leaf of houttuynia, wash it, pound it into a mash, mix it with egg white, and apply it to the affected area. Alternatively, pound houttuynia together with fresh herbs such as dandelion (pugongying) and golden-rod (yizhihuanghua) and apply the mash to the lesion. In my childhood I personally saw my father use external herbal applications to treat superficial swellings such as cellulitis and ding (boils); they were basically cured within twenty-four hours, far faster than Western intravenous infusion therapy.
To treat TCM external-medicine diseases, a decoction of houttuynia can also be used for fumigation and washing. For example, to treat swollen, hard, painful, and itchy anus or hemorrhoids, the anal area can be fumigated and washed with a houttuynia decoction. To treat scabies and psoriasis, the houttuynia decoction can likewise be used for frequent fumigation and washing; such external use is more effective than oral administration.
Houttuynia has a good effect in treating various types of pneumonia. For pneumonia, the juice of the fresh herb works best, because heating destroys the active constituents. Fresh houttuynia juice inhibits a variety of Gram-positive and Gram-negative bacteria, including Staphylococcus aureus and Diplococcus pneumoniae. It can be widely used to treat various upper respiratory tract infections, bronchitis, pneumonia, and tonsillitis. The Jiangxi Caoyao (Jiangxi Herbs) also records using houttuynia for viral pneumonia: houttuynia, magnolia bark (houpo), and forsythia (lianqiao), each 9 g, are ground into powder; 30 g of mulberry twig (sangzhi) is decocted in water, and the powder is taken with the mulberry-twig decoction; this is effective for viral pneumonia. Note that houttuynia and the other herbs here are not decocted.
Houttuynia is also widely used in treating various cancers. In the Kang'ai Zhongcaoyao (Anti-Cancer Chinese Herbal Medicines) edited by Yang Jianyu et al., houttuynia is listed as one of the commonly used anti-cancer herbs. According to that book, houttuynin has a marked inhibitory activity against Ehrlich ascites carcinoma in mice, with a maximum inhibition rate of 45.7% on cancer-cell mitosis; clinically it is commonly used for cancers such as lung, intestinal, cervical, liver, and thyroid cancer that present as internal exuberance of heat-toxin and obstruction by phlegm-heat. I once saw an elderly TCM physician use houttuynia for a patient whose submandibular tumor had worsened after radiotherapy. When using such herbs to treat cancer, it is best again to use the fresh herb, crushed for juice or brewed with warm water as a tea drunk frequently, so as not to destroy the active constituents.
Houttuynia can enhance human immunity. Modern pharmacological experiments have confirmed that both the houttuynia decoction and houttuynin can strengthen the phagocytic function of white blood cells. Synthetic houttuynin can raise the level of serum properdin; in patients with chronic bronchitis, it can be observed to enhance the phagocytic function of leukocytes, and four days after administration the serum properdin level has doubled compared with before treatment.
Modern biological research has shown that the genes that suppress inflammation in the human body are among the longevity genes. Most plant medicines that suppress inflammation can also markedly prolong human life. I live in the countryside, where in summer villagers most like to make their own herbal tea from houttuynia; some very long-lived elderly people also drink houttuynia tea frequently, and indeed no side effects have ever been observed. The claim that houttuynia is toxic is clearly a malicious slander against Chinese medicine.