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coltsfoot

What Is It?
Health Benefits
Dosage Information
Guidelines for Use
General Interaction
Possible Side Effects
Cautions
References
Evidence Based Rating Scale

 

What Is It?

Coltsfoot (Tussilago farfara) may qualify as the world's oldest cough remedy.  For centuries folk healers have used the bright yellow flowers, roots, and wooly leaves of this daisy family member to suppress dry coughs and soothe sore throats.  In fact, part of the plant's scientific name, Tussilago, stems from the Latin word for "cough."  In eighteenth-century France, for instance, shop owners painted an image of the plant on their signs to let passersby know that they sold healing herbs.  It has also been an important part of Chinese folk medicine for hundreds of years.

Other common names for the Herb include coughwort, cough plant, and horse-hoof (a nod to its hoof-shaped leaves).  It's also sometimes written “colt's foot”. In addition to treating coughs, coltsfoot also has a reputation for easing chronic respiratory problems such as asthma and bronchitis.  Although native to Europe, this ground-hugging perennial can also be found growing wild in northern parts of the United States and southern Canada.

Enthusiasm for this ancient healing herb has been dampened in recent years by the discovery that coltsfoot contains potentially liver-toxic and carcinogenic substances called unsaturated Pyrrolizidine Alkaloids (PAs).  (1, 2) For this reason, most sources recommend against using the herb altogether in oral form.  The FDA, in fact, classifies coltsfoot as an herb of "undefined safety", and a number of other countries restrict the medicinal use of the herb.  Many sources contend that, given the vast array of cough preparations now on the market, it makes sense to avoid one that has the potential to cause serious liver damage.

Germany's renowned Commission e, previously endorsed the herb if dosages delivered in tea were less than 10 mcg of PAs daily and fresh juice or extracts provided less than 1 mcg per day.  (3)  However the more recent translation of the German Commission E monographs does not include it.  (12) Alternative sources indicate that coltsfoot should not be used for more than four to six weeks at a time or for more than four to six weeks in a year.  (4-6)

Health Benefits

A gooey substance in coltsfoot called mucilage accounts for much of this ancient healing herb's reputation for coating, soothing, and protecting delicate Mucous membranes.  In fact, at one point coltsfoot ranked among the most popular European remedies for chest and respiratory conditions, from laryngitis to bronchitis.  Certain other compounds identified in the herb have anti-inflammatory and antibacterial actions.

Topical formulations (ointments, poultices, powders) also take advantage of this mucilage content.  Folk healers have also treated insect bites, skin inflammations, and burns with coltsfoot formulations.  However, we are unable to find any scientific evidence for the efficacy of these uses.

Specifically, coltsfoot may help to:

Reduce the urge to cough and soothe a sore throat. Traditional use for coltsfoot was most often for a dry (nonproductive) cough, because the herb helps coat and soothe the throat, making it less vulnerable to irritation.  The plant's high mucilage content is credited for this use. Germany's Commission E formerly endorsed the use of coltsfoot for dry coughs, hoarseness, and Inflammation in the mouth and throat.  (3) However, scientific evidence regarding this use is lacking.  Other alternative sources indicate that coltsfoot is an effective expectorant (agent for increasing secretions) in treating chest conditions but warn against continued use or prolonged exposure to PAs.  (4-8)

Minimize asthma-related wheezing.  Coltsfoot has a long history of use for asthma and other respiratory diseases in Chinese and European herbal medicine.  Recent research indicates that substances in the buds of the coltsfoot plant suppress the body's production of platelet-activating factor (PAF), a Protein in the blood involved in triggering the narrowing of the air passages that prompts wheezing.  (9) In a preliminary study done in China in 1989, 66 people with asthma experienced some decrease in airway obstruction when taking a mixture of six herbs in a combination that included coltsfoot.  (10) However, it is unclear what coltsfoot contributes to the effect of the combination.  Additionally, Chinese herbal combinations are often formulated with the belief that the adverse effects of one herb may be cancelled out by another, perhaps making the combination safer.  More recently, a study done in Russia showed that mice exposed to an allergen were less likely to die from anaphylactic shock if given coltsfoot and other herbs.  (11) The potent PAs in coltsfoot may someday be put to good therapeutic use when the quantity and quality is able to be well-controlled.  However much additional research will be needed.

Dosage Information

Special tips:

Given the presence of potentially liver-toxic and carcinogenic PAs, albeit in variable and often very small amounts, we do not recommend using coltsfoot.

General Interaction

Coltsfoot has potential adverse interactions with other medications and herbs that have anti-coagulant effects and could theoretically increase the risk of bleeding.

Concomitant use of other herbs containing hepatotoxic Pyrrolizidine Alkaloids (PAs) is contraindicated due to the risk of additive toxicity.  Herbs containing hepatotoxic PAs include: alkanna, boneset, borage, butterbur, coltsfoot, comfrey, forget-me-not, gravel root, groundsel, hemp agrimony, and hound's tongue; and the Senecio species plants dusty miller, groundsel, golden ragwort, and tansy ragwort. 

Coltsfoot has anti-hypertensive effects and should not be combined with other medications, supplements, or herbs that may increase the risk of hypotension.
Other herbs and medications that are metabolized in the liver by the Cytochrome P450 3A4 (CYP3A4) system, e.g., St. Johns wort, are likely to increase the risk of toxicity. 

Those who are allergic to other plants in the daisy (Compositae) family, such as chamomile and ragweed, may also be allergic to coltsfoot. 

Possible Side Effects

No immediate side effects of use are reported.  Delayed risks include liver toxicity and cancer.

Cautions

Widely variable amounts of the toxic unsaturated Pyrrolizidine Alkaloids (PAs) have been found in the flowers, leaves, and roots of the plant, and there is great individual susceptibility to the toxin.  At high doses, PAs can damage the liver sometimes months after it is used.  Thus it is impossible to establish a dose of the herb that would be generally safe when taken orally.  When used at even moderately elevated doses over weeks and months, the PAs could conceivably lead to liver cancer, as it has in laboratory animals.

Those with a history of liver disease, those who use alcohol, or those who take other medications that are metabolized in the liver, including acetaminophen, should avoid taking the herb.  

Because of potential health risks to a developing fetus, individuals who are pregnant or trying to conceive should avoid taking coltsfoot.

References 

1. Hirono I, Mori H, Culvenor CC. Carcinogenic activity of coltsfoot, Tussilago farfara I. Gann. 1976 Feb;67(1):125-9.
2. Chou MW, Fu PP. Formation of DHP-derived DNA adducts in vivo from dietary supplements and chinese herbal plant extracts containing carcinogenic pyrrolizidine alkaloids. Toxicol Ind Health. 2006 Sep;22(8):321-7.
3. Blumenthal M, Busse WR, Goldberg A, et al. (eds) The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Austin: American Botanical Council and Boston: Integrative Medicine Communications. 1998:114-5.
4. Chevallier A. Encyclopedia of Medicinal Plants. New York: DK Publishing, Inc., 1996.
5. Chevallier A. The Encyclopedia of Medicinal Plants: The Definitive Reference to More Than 500 Herbs and Remedies for Common Ailments. 2nd ed. December 1, 2000;278-9.
6. Natural-Medicinal-Herbs.com. Coltsfoot. http://www.natural-medicinal-herbs.com/herbs/coltsfoot.htm. Accessed January 11, 2011.
7. Herbs2000. Coltsfoot, Tussilago farfara. http://www.herbs2000.com/herbs/herbs_coltsfoot.htm. Accessed January 11, 2011
8. MotherNature.com. Coughing. http://www.mothernature.com/Library/Bookshelf/Books/41/37.cfm. Accessed January 11, 2011.
9. Hwang SB, Chang MN, Garcia ML, et al. L-652, 469 – a dual receptor antagonist of platelet activating factor and dihydropyridines from Tussilago farfara L. Eur J Pharmacol. 1987;141:269-81.
10. Fu JX. Measurement of MEFV in 66 cases of asthma in the convalescent stage and after treatment with Chinese herbs. Zhong Xi Yi Jie He Za Zhi. 1989 Nov;9(11):658-9, 644.]
11. Danilets MG, Belska NV, Bel'sky YP, Uchasova EG, Trophimova ES, Ligatcheva AA, Guriev AM, Belousov MV, Ahmedganov RR, Usubov MS, Agaphonov VI. Effects of plant water-soluble polysaccharides on the production of immunoglobulins E and G1 by lymphocytes of mice sensitized with ovalbumin. Bull Exp Biol Med. 2008 Nov;146(5):585-7.
12. Blumenthal M, Ed. Herbal Medicine: Expanded Commission E Monographs, American Botanical Council, Integrative Medicine Communications, Newton, MA, 2000.

Evidence Based Rating Scale

The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies and what our clinical advisors have found to be efficacious in their personal practice into a visual and easy to interpret format. This tool is meant to simplify the information on supplements and therapies that demonstrate promise in the treatment of certain conditions.

 

Condition

Rating

Explanation

 

Cough

 
 

Although alternative sources indicate efficacy as a demulcent and expectorant when taken at safe dosages for limited periods of time, it is impossible to establish safe doses given individual variation in sensitivity to the constituents and insufficient labeling in the U.S.


Date Published: 04/18/2005
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