Despite given too much blame or too much praise, cantharides (Ban Mao), considered as one of toxic herbs, have long been a controversial Chinese herb. Cantharis tends to inhabit and feed in groups. Viewed as an insect pest, it is hatched in spring and feeds on leaves, buds, and flowers of cash crops like soybean, peanut, eggplant, and cotton, etc. This unlovely little creature, however, is also one of valuable Chinese medicine in the eyes of TCM practitioners. According to Ben Cao Gang Mu (Compendium of Materia Medica), it treats a range of disorders from sores to cancers.
What are cantharides (Ban Mao)?
It refers to the dried insect Cantharis vesicatoria or Lytta vesicatoria. In TCM, medicinally there are two different species – Mylabris phalerata Pallas and M.cichorii Linnaeus. But commonly it is also called as Spanish fly and blister beetle.
The dried whole insect is oblong, 1.5 to 2.5cm long, 0.5 to 1cm wide, with sagging head and mouthpart, a pair of sizable compound eye and antenna respectively, and most antennas dropped. It has 1 pair of black leathery elytrum, with three yellow or brownish yellow cross grain, and 2 pieces of dark brown transparent film-type endopterygota underneath. The abdomen and chest are black in color, with 3 pairs of feet. And it is with special odor.
What is cantharis used for?
Cantharis once was used as diuretic internally and topical vesicant, rubifacient, and counterirritant externally. Medically it is commonly used to remove warts and even, proposed by many, to fight cancers. However, the most well-known application for cantharid is used as an aphrodisiac because of cantharidin, the active constituent contained in cantharides. Reportedly, oral intake of Cantharis may lead to urinary tract infection and genital swelling, to priapism in larger dose, and even worse to death in over dose. Aphrodisiac made from cantharides, for that reason, are not allowed using on human in USA.
Property and indications
In Chinese herbal remedies, it is believed as acrid, hot, and with acute toxicity in nature and covers meridians of liver, stomach and kidney. Main functions are to drastically remove blood stasis and resolve static blood, disperse clumps, vesiculate and conduct redness, and eliminate toxins, etc. Main usage and indications are abdominal lumps, chronic tinea, crewels, wart, non-healing boils, and necrotic tissues due to sores. Usual dosage is 0.03 to 0.06 grams.
According to the latest study, it has specific efficacy for malignant tumor and skin diseases like leucoderma and psoriasis. In addition, it is helpful on alopecia areata by regenerating hair and on viral hepatitis for the effective inhibitory action. Due to its poisoning property, clinically it is recommended to use externally only with tincture of cantharides.
In summary, its newly found functions are as follows:
(1). Significant antitumor effects. Cantharides extract can restrain the cell metabolism in treatments of carcinoma of the esophagus, cardiac carcinoma, gastric cancer, lung cancer, and sarcoma of the spleen;
(2). Antiviral effect;
(3). Anti-inflammatory and anti-fungal activity;
(4). Increasing leucocytics function;
(5). Fighting liver injury and rise of GPT caused by carbon tetrachloride;
(6). Immunosuppressive effect;
(7). Promoting androgens effect;
(8). Vesiculation functions.
Related Chinese herbal formulas
(1). Recorded in Renzhai Zhizhi Fanglun, Cantharides powder treats ulcer, non-healing boils, and swollen hard rupturing bump without pus;
(2). Listed in Ji Lin Zhong Cao Yao (Chinese Medicinal Herb in Jilin), the combination with Gan Sui (Kan Sui Root) cures psoriasis in powder;
(3). Collected in Ben Cao Gang Mu (Compendium of Materia Medica), the mash of cantharides, sticky rice (fried), and garlic can be used to remove warts;
(4). Reported in Yao Xue Tong Bao (Chin Pharm Bull), 1980, 15(5): 271, it was used for liver cancer. Pick 5 to 6 cantharides with head, wings, and feet removed, and then place it into an egg and roast with slow fire. When dried, grind them into powder in 2 parts, each one time, and 1 to 3 doses each day. The longest record was continuous 14 months, which shows that it could prolong the survival time in the patients with primary hepatic carcinoma and relieve the symptoms.
The related list of Chinese herbal formulas can be much longer, to name but a few here.
Possible side effects and contraindications
Since this is one of toxic herbs, it may cause poisoning symptoms as follows if used the wrong way:
(1). Nausea, vomiting, intense burning sensation in entire digestive tract;
(2). Frequent micturition, urgent urination, odynuria, hematuria, proteinuria, or even kidney failure;
(3). Symptoms of digestive tract, such as vomit, severe abdominal pain, even ulcer and hematochezia, etc.;
(4). Local stimulating signs, like burning sensation in dermal mucous, pain, thirst, difficult swallowing, bleeding, edema, and blistering, etc.;
(5). Impairment of central nervous system, such as unconsciousness, coma, difficult eye movements, diplopia, language difficulties, numb lips, even limb paralysis and weak limbs, etc.;
(6). Symptoms of impairment of renal system, like dysuria, hematuresis, micturition pain, low back pain, infection in urinary system, even liver function damaged and kidney failure, etc. The poison could kill if not treated in time.
So, extreme care should be used when applying cantharides, especially in oral intake. Go for a registered TCM practitioner for the professional opinion when needed because this is a toxic herb, which need to be used strictly by the indications and should avoid abusing it under any circumstances.