A Popular Remedy Escapes Notice of Western Practitioners

by Subhuti Dharmananda, Ph.D., Director, Institute for Traditional Medicine, Portland, Oregon


Bidens refers to several species of plants used as sources of the traditional Chinese medicinal herb most often known as guizhencao (gui = demon or ghost, zhen = spike, needle, cao = weed, plant), its name making reference to the characteristic barbs on the fruits. The English-language common names for the herb, such as "railway beggar's tick," come about because the barbs stick to one like a tick, and it is usually seen on the clothing of those who wander through along roads and railways, such as beggars. In Europe and the Americas, the herb is known as Spanish needle. The Chinese herb xanthium fruit is a relative; the barbed fruits of that herb are used as medicine and must be handled carefully or they can cause injury. Descriptions of injuries from bidens spikes (mainly infection from cuts received) have appeared in the medical literature.

Bidens is a member of the Asteraceae (formerly called Compositae) family, which is one of the dominant families of plants contributing medicinal species not only in China but worldwide. The species of Bidens that is best known to botanists, horticulturists, and herbalists is Bidens pilosa (pilose = covered with fine soft hair), which is a tropical weed. It is used as an herbal medicine in many parts of the world, including southern China, Africa, and Central America. This herb has been used since ancient times in China, and especially in Taiwan, which has a tropical climate. Bidens pilosa is sometimes specified in China as sanye guizhencao (san = three, ye = leaf), because its leaves are in groups of three leaflets (see Figure 1), though this is seen in other species as well; another Chinese name for it is xianfengcao (abundant weed). Bidens pilosa is commonly found growing along roadsides, railroad tracks, vacant lots, and other places where the ground has been disturbed, including the shores of rivers of ponds.

Additional species of Bidens (11, 12, 13), including non-tropical ones, are also used in Chinese herbal medicine (see Table 1). Numerous other species of Bidens that do not grow in China are used in other countries for medical applications that are similar to those described by the Chinese.

Table 1: Main species of Bidens used in Chinese herbal medicine. These are used interchangeably.

Botanical Identification Chinese Name and Translation Comments

Bidens bipinnata

nianshencao (stick to the body weed)

primary species used in mainland China

Bidens biternata = Bidens chinensis

jinzhan yinpan (gold cup silver plate; flower has bright yellow center with white flowers)

substitute for Bidens bipinnata and Bidens pilosa

Bidens parviflora

xiaohua guizhencao (small flower bidens); lujiaocao (deer antler herb); cizhencao (prickly bidens)

substitute for Bidens bipinnata

Bidens pilosa

sanye guizhencao (three-leaf bidens)

tropical bidens used worldwide in herbal medicine

Bidens tripartita

longbacao (wolf's grasp weed)

known as a remedy for chronic dysentery

Certain Desmodium species (from the Leguminaceae family) are sometimes used as substitutes for Bidens in China because they have the same applications. In all cases, the whole plants are collected for medicine, usually during late summer and early autumn.

According to Smith and Stuart (19), the Bencao Gangmu (1596 A.D.) listed two types of bidens, guizhencao and longbacao, the former mainly used for treating poisonous bites of insects and snakes and the latter mainly for chronic diarrhea.

Unlike many modern source texts (Materia Medica guides) which fail to list bidens at all, or present one or more of the species under a single heading (guizhencao), Oriental Materia Medica (7) lists Bidens pilosa and Bidens bipinnata (nianshencao) separately. Bidens pilosa is included among the clear heat and toxin herbs. It is said that the nature of the herb is sweet and bland, with a neutral property, though other sources (8, 10) list it as bitter. Its actions are to expel pathogenic factors from the surface of the body, clear up heat, remove toxin, and eliminate stagnancy. The applications listed include influenza, swollen and sore throat, enteritis, dysentery, jaundice, intestinal carbuncle, epilepsy in children, malnutrition in infants, and hemorrhoids.

In Chinese Medicinal Herbs of Hong Kong (10), the indications for Bidens pilosa (the only species listed) are:

  1. influenza, colds, fever, sore throat;
  2. acute appendicitis;
  3. acute infectious hepatitis;
  4. gastroenteritis, dyspepsia;
  5. rheumatic arthralgia;
  6. malaria; and
  7. hemorrhoids, pruritis.

Bidens bipinnata is listed in Oriental Materia Medica among the herbs that are cooling and resolve the surface. It is reported to have the functions of removing wind-dampness, dispersing stagnant blood, and invigorating blood. This categorization of this herb-along with those usually indicated for resolving the surface-appears to be in error, as there is a different section of the Materia Medica reserved for herbs that have the properties listed for this species of bidens, namely the herbs for removing wind-dampness (anti-rheumatics). Applications of the herb in Oriental Materia Medica include rheumatoid arthritis, sprain, insect and scorpion sting, diarrhea, dysentery, hepatitis, acute nephritis, stomach ache, and sore throat. In sum, it has the same uses as Bidens pilosa. The substitute Desmodium species are similar to the standard herb known either as hulucha or longshehuang (Desmodium triquetri), which is applied to treat common cold, sore throat, enteritis, dysentery, jaundice, rheumatic arthralgia, and other disorders; the overlap in applications between bidens and desmodium is evident.

A review of uses of Bidens bipinnata (the only species mentioned) in Anticancer Medicinal Herbs (9), includes:

In Chinese-English Manual of Common-Used Herbs (14), under guizhencao, three species are all listed as source materials: Bidens bipinnata, B. pilosa, and B. biternata. The applications are:

  1. clear away the superficial heat: for common cold of wind-heat type and prevention of influenza;
  2. clear away heat and toxic materials: for sore throat, appendicitis, snake bite, and centipede bite; and
  3. clear away dampness and heat from the gastrointestines [gastro-intestinal tract]: for diarrhea, dysentery and stomach ache of heat type.

According to A New Compendium of Materia Medica (12), the Bidens species have the following properties (with B. pilosa listed as the main species and B. bipinnata and B. tripartita listed as having the same uses):

Good for diminishing inflammation to cure common cold, bronchitis, hepatitis, tonsillitis, pneumonia, appendicitis, and child-fever, eliminating sputum and relieving cough and asthma; also for curing snake bite or for external applications.

In Thousand Formulas and Thousand Herbs of Traditional Chinese Medicine (30), Bidens parviflora is mentioned twice (lujiaocao, cizhencao) within the section on herbs that clear heat and remove toxin. It is said to clear heat, detoxify, motivate blood circulation, and remove stasis. Uses include fever, coughing, and sore throat in common cold; enteritis, diarrhea, and appendicitis; infantile fever with convulsions; trauma, frostbite, itching skin rash, carbuncles and furuncles, or snake bites (for the latter applications it can also be used topically, by pulverizing the herb).

These slightly differing renditions of the uses of bidens probably do not reflect species differences in the source materials; there has been extensive substitution of species and there is likely some confusion in assigning certain properties to certain species. A mixture of guizhencao (identified as Bidens bipinnata) and xiaohua guizhencao (B. parviflora) has been used in studies of the effects of bidens, perhaps as a means of assuring the presence of essential active constituents representative of the Bidens genus.

The recommended dosage of the herb is as little as 9-15 grams per day for the heat-cleansing therapies, and as high as 60-120 grams in decoction, divided into four daily doses, for treatment of acute appendicitis (10). Typical daily doses mentioned in the literature are 15-60 grams per day. The herb, along with others, is included in the Chinese Patent Gan Mao Qing, a remedy for common cold and influenza. For topical use, the fresh herb is crushed and applied locally or boiled in water to produce a wash for boils, eczema, and tinea.

Based on the traditional claims, bidens would be expected-from the modern perspective-to show infection-inhibiting and antiinflammatory properties: these actions have been investigated and shown to exist. In fact, bidens extracts are shown to inhibit bacteria, fungi, and viruses and to have potent antiinflammatory effects in laboratory animal experiments with induced gastric ulcer, liver inflammation, or arthritis-type swelling. In Anticancer Medicinal Herbs, the anticancer potential of the herb is said to be implied by its bacteria inhibiting actions (since many antibacterial substances also inhibit cancer).


There are two main groups of active constituents of bidens: polyacetylenes (see Figure 2), which inhibit various pathogenic organisms, and flavonoids, which reduce inflammation. The polyacetylenes can also manifest an antiinflammatory action, probably mediated by a different mechanism than the flavonoids. Bidens also has friedelane triterpenes and essential oils which may contribute to the observed therapeutic action of the herb. Analyses of various species of Bidens have been conducted in several countries. Although there is some variation in the level of activity of the different species of Bidens, probably due to different levels of active constituents, the general properties appear similar.


Polyacetylenes are hydrocarbons that strongly absorb long-wave UV light; their medicinal activity is altered upon exposure to light (photoactivation). Extracts of bidens and other herbs in the same plant family have been shown to inhibit bacteria, yeast, and insect larvae in laboratory experiments; the effect is diminished or eliminated in darkness (20). These compounds can also inhibit human fibroblast cells, but not human skin cells (fibroblasts, when activated, may produce undesired hardening-fibrosis). Such photoactivation makes these herbs particularly valuable for topical application, since simple sun exposure will make them especially active when applied to the skin. Bidens pilosa is reported to be used as a traditional topical remedy not only in China, but also in Africa, Central America, and even Hawaii. By eliminating pathogenic organisms that infect wounds, the wounds will heal faster and more completely. A daytime application of the crushed herb would be more effective than an overnight application.

When used as an internal remedy, one relies partly on the lower activity of the non-activated polyacetylene components (the dosage of bidens for treating infections tends to be high, typically 30 grams or more per day), and there can be some photoactivation of the components as they pass through the capillary beds under the skin if one is exposed to strong enough light (sunlight or from fluorescent light bulbs). Bidens pilosa, being a tropical herb, is most commonly used by persons who have ample opportunity for strong sun exposure.

The polyacetylenes from Bidens pilosa have also been shown to inhibit the malarial parasite Plasmodium falciparum, which may explain its use in the Amazon region to treat malaria (24). In laboratory experiments, the extracts of bidens in various liquid media showed antimicrobial activity (1), and the combination of bidens, chrysanthemum, and houttuynia was shown effective for inhibiting Mycobacterium tuberculosis (16). The principal constituent in the leaf of bidens, phenylheptatriyne (PHT), one of the polyacetylenes that has been widely studied, has antimicrobial activities and antiviral effects (8) that are augmented by UV light exposure. The polyacetylenes are one of the few natural substances reported to inhibit cytomegalovirus (CMV), a type of herpes virus that causes disease in immune-compromised individuals. Importantly, these polyacetylenes to not cause DNA changes (as do other herbal photoactivated substances, such as furanocoumarines found in the Umbelliferae plants), and the action appears to be mediated by cell surface activities (27); this implies a higher level of safety for their use.

In a survey of antibacterial activity of South African herbs, of 21 species tested, Bidens was one of only 4 species with high activity: it inhibited gram-positive bacteria (25). The activity was found in the fraction that separates polyacetylenes from most other components. The photo-activated polyacetylenes may also inhibit tumor cells. Bidens was included in a ten-herb formula tested and shown beneficial for cancer inhibiting effects in mice (17). Polyacetylenes isolated as a minor component from ginseng were shown to have a strong cell-growth inhibition when applied to cultured cancer cells, but not when applied to normal cells (28, 29).

At least five polyacetylenes obtained from the hexane extract of Bidens campylotheca showed significant in vitro inhibition of cyclooxygenase (CO) and 5-lipoxygenase (5-LO); inhibiting these enzyme systems is a means of reducing inflammatory responses (6).


The specific flavonoids in Bidens have not been fully elucidated, though the following have been found: luteolin (12, 15); a group of flavonols having quercetin as their aglycone; and a group of chalcone glycosides (18). Luteolin (see Figure 3) is a commonly-occurring compound that is also found in other Chinese "antitoxin" herbs, such as chyrsanthemum, lonicera, and wisteria; quercetin is a frequently-occurring plant flavonoid with potent medicinal actions; and chalcones are best known from licorice; which has antiinflammatory activity.

Several of the flavonoids found in Bidens pilosa have antiinflammatory activity as revealed in laboratory animal studies (1). The antiinflammatory effect of aqueous extracts of bidens against paw edema induced by carrageenan and chronic arthritis induced by complete Freund's adjuvant were determined in rats (2). The results indicated that paw edema induced by carrageenan was significantly decreased by treatment with aqueous extracts (150 or 300 mg/kg) of bidens. The effect of Bidens pilosa was the most potent of three Taiwanese varieties tested. The extract (500 mg/kg) of Bidens pilosa significantly decreased the paw edema induced by Freund's adjuvant.

The potential effectiveness of bidens as an antiinflammatory for the liver was tested in rats with acute hepatic lesions induced by carbon tetrachloride and acetaminophen (3). The results indicated that the increase in liver enzyme (SGOT and SGPT) activities caused by these liver toxins could be significantly reduced by treating with the extracts of bidens; histological observation confirmed the protective action of the herb.

Effects of the flavonoid fraction of Bidens aurea on gastric ulceration induced by stress (restraint and cold) were studied in rats (4). Mucosal damage was evaluated and the results of bidens flavonoid administration were compared with those of established drugs (omeprazole and ranitidine). Oral treatment with the ether fraction of the flavonoid extract gave the highest level of gastric protection. Mucus content was increased and accompanied by a proportional increase in proteins and hexosamines. There was also a marked increase of neutral and sulfated glycoproteins, which are protective substances in the mucus. The groups that received ranitidine and omeprazole did not overcome the inhibition of the mucus secretion induced in this experimental model.

A study was designed to elucidate the mechanism of the healing process mediated by the flavonoid fraction of Bidens aurea on chronic gastric ulceration induced by 5% acetic acid in rats (5). The diethyl ether extract of bidens (125 and 62.5 mg/kg body weight) was administered in a single dose, 7 and 14 days after provocation of lesions. Both doses significantly decreased the macroscopic and microscopic ulcer index. Usually after 14-days of treatment the lesions were found completely covered with regenerative epithelium and a proliferation of blood vessels was observed. Application of acetic acid produced a significant increase in leukocyte infiltration (part of the inflammatory response) 7 days after induction of chronic injury; the macroscopic examination showed a drastic reduction of leukocyte infiltration in groups treated with bidens extract. These results suggest that the recovery of vascularization of the ulcerated area and the decrease of neutrophil infiltration are involved in the antiulcer effect of the flavonoids.

In a screening of traditional herbal medicines in Zululand, plants that were used to treat headache or inflammatory diseases were analyzed (26). Of the 39 species tested, Bidens pilosa had one of the highest activities for inhibiting cyclooxygenase (an enzyme of the prostaglandin synthesis pathway that leads to pro-inflammatory prostaglandins); such inhibition is associated with the flavonoid components.

Flavonoids are often used in the treatment of cardiovascular disorders, and the extracts of bidens show all the activities expected from its flavonoid components. A mixture (7:3) of guizhencao (listed as B. bipinnata) and xiaohua guizhencao (listed as Bidens parviflora) was found to inhibit platelet aggregation in rat tests (21); the same mixture was shown to lower the amounts of beta-lipoproteins and cholesterol in the blood plasma of laboratory rats, and it inhibited thrombosis (22). The methanol extract of Bidens pilosa was evaluated in spontaneously hypertensive rats (23) and shown to produce a hypotensive effect that appeared to be due to vasodilation.


Bidens tripartita (longbacao), which has been known for many centuries as a remedy for chronic dysentery, was used in a clinical trial to treat 500 cases of dysentery, 65 cases of acute enteritis, 248 cases of chronic enteritis (15). Different forms of the herb were used to make the medicine for a one day dose, each time, divided into three doses:

The granules and tablets (made of the granules) were administered in a total dosage of 15 grams per day; this amount is derived from about 75 grams of dried herb. The herbal materials in various forms were administered for 3-10 days, administered to patients who had already suffered from diarrhea for 7-15 days. In 500 cases of dysentery, 387 cases were reported cured; with 13 not responding in 3 days. In 313 cases of enteritis, all were cured (12 chronic cases relapsed later). The authors of the study pointed out that there had been an epidemic of dysentery in Shandong Province for many years and that practitioners at village clinics and the county hospital in Jianan County had used bidens as a remedy for about 10,000 patients. This study was undertaken to more rigorously evaluate its effectiveness. The herb is said to be of value because it is abundant, easy to collect, and simple to prepare.


Bidens is a popular herb in China, mainly used as a folk medicine, meaning that it is collected and used by laypersons to treat common ailments: dysentery, skin diseases, poisonous bites. It is also one of the mainstream herbs of the Chinese tradition, with two types included in the authoritative compendium of the 16th century, the Bencao Gangmu. Western students of Chinese medicine are not introduced to this herb because it is not mentioned in the traditional formulations presented in modern textbooks.

In revealing more information about bidens, Western students can better appreciate the broad extent of herb use in China, and are introduced to two categories of active constituents (polyacetylenes, flavonoids) that help to explain the traditional uses of the herb.


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Figure 1: Bidens pilosa in flowering stage;
note the three-leaflet pattern.

Figure 2: Polyacetylenes isolated from
several species of Bidens.

Figure 3: Luteolin, one of the flavonoids isolated from Bidens.