Cantharides. Cantharis vesicatoria.

Botanical name: 

Synonyms—Spanish Flies, Blister Beetle.

Cantharidin, extractives, salts and fat.

Cantharidin is a crystalline body obtained by exhausting the powder with chloroform. The crystals are colorless prisms, soluble in alcohol, chloroform, ether and in volatile oils, and to a limited extent in water. It is the irritating, blistering constituent of the powder.


Tinctura Cantharidis, Tincture of Cantharides. Dose, from one to ten minims.
Specific Cantharis. Dose, from one to five minims in water.
With many physicians the agent is always prescribed in small doses frequently repeated—from five to fifteen drops in four ounces of water, a teaspoonful every one, two or three hours.
Ceratum Cantharidis—Cantharides cerate, made of cantharides, yellow wax, lard and turpentine.

Physiological Action—Internally the agent will produce gastro-intestinal irritation, pain, nausea, vomiting, bloody stools, suppression of urine, with irritation in passing, strangury, swelling of the external genitals, general depression, convulsions and death. It increases sexual desire, and is an active emmenagogue and abortifacient.

Applied externally the agent produces at first, local stimulation, a reddening of the skin and subsequent vesication, the vesicles filling with serum, producing prompt and marked derivation and general depression.

Therapy—In small doses this agent is in use in the treatment of cystitis and bladder irritations, accompanied with tenesmus and constant desire. It is serviceable in enuresis when there is relaxation of the bladder walls, and lack of control of the sphincter, especially in that common to relaxed plethoric women, when upon their feet, and when coughing.

It is of some benefit in the treatment of dropsies, especially of those following scarlet fever, and diabetes in its later stages.

It is occasionally beneficial in eczema and acne, when accompanied with uterine or vesical irritation, or with amenorrhea. In small doses it is prescribed in sub-acute or chronic gonorrhea or gleet.

As a vesicant, or blistering agent, cantharides has long been used in the treatment of local inflammations of all characters, usually in sthenic stages, as its derivative influence produces debility. Diseases of the brain and spinal cord, and their meninges, have been treated with extreme derivation from its, action and often with good results. As a local stimulant in hypostatic congestions the agent has been much used, being applied in such cases short of vesication.

Strangury induced by the use of this agent may be treated by the use of a solution of potassium hydrate in frequent doses from ten to twenty drops freely diluted.

Very small doses of the tincture of cantharides—one drop diluted in eight ounces of water—will be of sufficient strength when a patient complains of pain in passing water, or when there are intense, burning, cutting, scalding sensations in the urethra. There may be tenesmus and urgent desire almost constant to urinate with a passing of only a drop or two at a time, which burns like fire. There may be hematuria also.

An old German treatment for cancers was made by the use of the tincture of cantharides in a medium sized dosage, prepared in the wine of camphor with mucilage of gum arabic. A number of cures were attributed to this.

Homeopathists give this remedy in minute doses when there is delirium with paroxysm of rage, profanity, greatly increased sexual excitement, or sexual furor.

A prominent French writer advised cantharides in very small doses in acute nephritis where there was at first anuria and oliguria. He gives this in medium sized doses, claiming a rapid increase in the amount of sugar, and disappearance in the edema.

Dr. Wark reports a case of fistula in a boy of sixteen which was cured with a cerate of cantharides to which he added a small quantity of the tincture filling a long fistula full of this. By this means he blistered off the pyogenic membrane of the fistula, and by simple measures healed the fistula completely.

An application is made of a mixture of one-half of a dram of tannic acid, one dram of tincture of cantharides, five drops of the oil of capsicum in two ounces of glycerine rubbed thoroughly into the scalp twice a day to prevent the falling of hair.

Dr. Thornton of Mississippi combined cantharidin and collodion and used it in his ears for chronic deafness with excellent results.

Note—Powerful vesication is seldom deemed advisable by our physicians as local stimulation by heat or mustard is usually found sufficient. The formation of large blisters or blebs is deprecated, as inducing depression and local pain and general irritation, usually out of all proportion to the benefit derived. The abstraction of the serum from the blood, which contains almost as much albumin as the blood itself, amounts to but little less than actual blood letting. Extreme blistering, even by physicians addicted to most heroic measures is largely relegated to the past.

When counter irritation, derivation, or local stimulation seems to be needed, we have recourse to local heat, dry or moist, always short of burning, mustard, capsicum, and other agents named in other chapters for their revulsive action, as croton oil, and other oils, chloroform, ether and ammonia, confined, and dry cupping.

The American Materia Medica, Therapeutics and Pharmacognosy, 1919, was written by Finley Ellingwood, M.D.
It was scanned by Michael Moore for the Southwest School of Botanical Medicine.