Coltsfoot

Coltsfoot was traditionally used as an antitussive cough medication, which explains its botanical name Tussilago (from tussis, coughing; ago, to chase) and its common name, coughwort. It is similar to Petasites vulgaris, butterbur, which can be a dangerous toxic contaminant in coltsfoot products. Both the flowers and the leaves of coltsfoot are gathered for herbal use.

Uses and Benefits:

Coltsfoot has been used as a candy and herbal remedy in different formulations for thousands of years. Oral preparations were advocated for use in cough and various respiratory diseases, and the smoke from burning coltsfoot leaves or from herbal cigarettes was also used for treating asthma and bronchitis. Other former indications included diarrhea and slow metabolism, and coltsfoot has been employed as a blood purifier and as a diuretic. It is relatively unique in having been selected by both traditional Western and Chinese herbalists for the same specific purpose-the treatment of cough.

Pharmacology:

One of the main contents of coltsfoot leaves is a mucilage. This polysaccharide macromolecule forms a colloidal solution or a gel with water; this is said to coat the mucosa of the pharynx and have a demulcent effecP Historically, there was a tendency to assume that the sticky quality of mucilages, which re­semble mucus, signified their inherent value as throat soothers or expectorant agents, and thus there arose the suggestion that the herbal sources of such products were helpful in coughs. Another component, tussilagone, has been reported to stimulate the res­piratory center and to increase blood pressure in animal models.

Components of greater concern are the pyrrolizidine alka­loids-senkirkine, senecionine, and seneciphylline-which are present in small amounts. Of these, senkirkine and senecioning contain unsaturated necine bases; in animals, these have been reported to cause hepatoxic, carcinogenic, and possibly pneumo­toxic effects.? European coltsfoot has smaller quantities of toxic compounds than some Chinese plants.

Coltsfoot also contains tannins, flavonoids, acids, bitters, and other constituents. Most of these have not been pharmacologi­cally evaluated, but an expectorant effect has been hypothesized to occur through stimulating gastric receptors to cause a vagal reflex in the lung that results in bronchial gland secretion. Coltsfoot flower buds contain a compound (L-652,469) which has platelet-activating factor inhibitory properties, but no clinical evaluation of this component has been made.

Clinical Trials:

In spite of its long reputation as a "pectoral" for treating respiratory disease, there is no clinical trial evidence demonstrating that the herb itself or its components have any useful effect in treating cough or asthma. It may be of empiric benefit for soothing sore throats, but there is no evidence that it is more effective than other syrupy drinks or candies. Since it is very difficult to prove that any drug is an effective expectorant, it is not surprising that coltsfoot has never been demonstrated to possess this property. There is no clinical evidence to support claims that it has any clinically useful properties.

Adverse Effects:

There are no known side effects with brief or occasional use.

Side Effects and Interactions:

There are no recognized interactions with coltsfoot, although use with potential hepatotoxic agents should be avoided.

Cautions:

Occasional reports have implicated the prolonged use of coltsfoot with the development of severe hepatic veno-occlusive disease; this is due to the hepatotoxic pyrrolizidine alkaloids. Coltsfoot should be avoided by patients with liver disease and by those ingesting potentially hepatoxic drugs and/or alcohol. Occasional concerns arise about the allergenicity and carcinogenicity of coltsfoot, but these claims have not been substantiated in humans. It should not be taken by pregnant or breast-feeding women. Any use of coltsfoot should be restricted to a few days so as to decrease the risk of toxicity.

Preparations & Doses:

Coltsfoot is commonly incorporated into candies and teas, which are particularly popular in France.It is also available in many European countries as solutions, syrups, and tablets. A typical dose is 0.6-2 ml of a flower extract or to 8 ml of a syrup. Dosages of dried herb vary from 600 to ,2000 mg t.i.d.

Summary Evaluation:

Coltsfoot has no clinically documented value as a respiratory r'rnedy. As the herbal leaf and other components of coltsfoot have toxic effects and lack proven value, their use is discouraged. is unlikely that small amounts given for a few days could cause significant harm. Nevertheless, safer herbs that may be more effective should be preferred for treatment of sore throats and coughs and for improving expectoration. Due to its potential toxity, coltsfoot is not recommended by leading herbal authorities.