Coltsfoot

Ass's foot, British tobacco, bullsfoot, coughwort, donnhove, fieldhove, flower velure, foal's-foot, foalswort, hallfoot, horse-foot, horsehoof, huflattichblatter, kuandong hua, Tussilago farfara

Coltsfoot contains 5% to 10% mucilage, which is believed to produce a soothing effect by physically coating the irritated mucosa of the mouth and throat. The plant's polysaccharides, flavonoids, and phenolic components may have anti-inflammatory and antibacterial activity. Also, the plant contains tussilagone, a sesquiterpene thought to have cardiovascular and respiratory stimulant properties, and a number of pyrrolizidine alkaloids, primarily senkirkine and senecionine, which are converted to toxic metabolites in the liver and have been associated with hepatotoxicity.

The dried leaf of coltsfoot is the part most commonly used for medicinal purposes. Although the flower also contains medicinal components, it's reported to have higher levels of pyrrolizidine alkaloids. Coltsfoot is available as tea, bulk leaf, capsules, leaf extract, and tincture.

Reported uses

Coltsfoot is used to soothe throat irritation and mild inflammations of the mouth and throat, to alleviate cough, and to treat symptoms of respiratory infections, acute and chronic bronchitis, laryngitis, asthma, colds, and emphysema. It's also used as a smoking mixture.

Administration

Leaf extract: 0.6 to 2 ml three times a day, not to exceed 1 mcg of pyrrolizidine alkaloids with a 1,2 necine structure . Tincture: 2 to 8 ml three times a day. Tea: Maximum of 6 g/day, or 10 mcg of pyrrolizidine alkaloids with a 1,2 necine structure; prepared by adding 1.5 to 2.5 g of cut leaf to boiling water.

Hazards

Adverse effects associated with the use of coltsfoot include lethargy, anorexia, abdominal pain (especially right upper quadrant pain) and swelling, nausea, vomiting, hepatotoxicity, liver changes and liver cancer, reversible hepatic venoocclusive disease, jaundice, and allergic reaction.

Excessive consumption of coltsfoot may interfere with the effects of antihypertensives and cardiac drugs. Herbal products prepared with alcohol may cause a disulfiram-like reaction.

Safety Risk Due to the risk of hepatotoxicity and liver cancer, coltsfoot isn't recommended for use by humans. Many countries have banned the internal use of other herbal products containing pyrrolizidine alkaloids because of the risk of liver toxicity.

Clinical considerations

• Recommend alternative therapies that aren't associated with severe adverse effects for example, over-the-counter lozenges or sprays.
• Some extracts may contain up to 45% alcohol, so children, alcoholic patients, those with liver disease, and those receiving metronidazole or disulfiram should avoid them.
• If patient has cancer or is undergoing chemotherapy, is pregnant or breast-feeding, or is planning pregnancy, advise against using coltsfoot.
• Some of coltsfoot's components may antagonize the effect of antihypertensives on blood pressure.
• Those with an allergy to plants in the Asteraceae family such as ragweed, marigolds, daisies, and chrysanthemums-may experience hypersensitivity reactions to coltsfoot.
• The active ingredient, a mucilage, is destroyed when burned and smoked.
• Monitor blood pressure and liver function test results, an watch for signs and symptoms of hepatoxicity, such as right upper quadrant pain, nausea, vomiting, abdommal distention, and Jaundice. Instruct patient to report any of these signs at once.
• Warn patient that use in higher doses or for longer than recommended may increase the risk of liver toxicity and malignancy.
• Regardless of the preparation used, therapy should last no longer than 4 to 6 weeks per year, to prevent exposure to large amounts of pyrrolizidine alkaloids. . Caution patient that manufacturers don't report the pyrrolizidine alkaloid content of their products, making it very difficult to determine the exact dose being ingested.
• Tell patient to remind prescriber and pharmacist of any herbal or dietary supplement that he's taking when obtaining a new prescription.
• Advise patient to consult his health care provider before using an herbal preparation because a treatment with proven efficacy may be available.

Research summary

The concepts behind the use of coltsfoot and the claims made regarding its effects have not yet been validated scientifically.