What Is Coltsfoot?

Coltsfoot is a perennial plant that grows up to 12 inches in height. The plant has golden-colored flowers that resemble dandelions. Coltsfoot originated in parts of Asia as well as in Europe, but the plant also grows throughout damp areas of North America and is known to flourish along roadsides and in meadows and hedgerows. 

As an herbal supplement, coltsfoot has been used both in traditional Chinese medicine (TCM) and Western herbalism, primarily as a treatment for sore throat and chronic (long-term) coughs (such as from emphysema).

Coltsfoot is also known as Folia farfarae, Filius ante patrem, and Kuandong Hua. The Latin name, Tussilago farfara, is derived from the word "tuss," meaning cough, and "lago," meaning to dispel, which also explains the term "anti-tussive."

What Is Coltsfoot Used For?

Coltsfoot is often mistaken for the dandelion plant. TThe flowers and leaves are the primary parts of the plant that are used for medicinal purposes, and the roots are usually avoided. The flowers die before the leaves appear, which is how coltsfoot originally got one of its name, Filius ante patrem, which translates to “the son before the father.” The common name, coltsfoot, evolved because the leaves resemble the foot of a horse.

Most studies involving coltsfoot have been done on animals and not on humans.

Coltsfoot has been traditionally used as:

• An antioxidant (to strengthen the immune system)
• An antitussive (to ease cough)
• An antimicrobial (to kill bacteria)
• An anti-inflammatory agent (to lower inflammation)

Medical Uses

Although coltsfoot is commonly used to treat several common maladies, again, there is a lack of clinical research evidence to back up these claims. Medical conditions said to improve with the use of coltsfoot include:

• Bronchitis
• Lung cancer
• Emphysema
• Rheumatism
• Tuberculosis
• Pertussis (whooping cough)
• Upper respiratory infections
• Sore throat
• Cough
• Asthma
• Wheezing
• Laryngitis
• Inflammatory skin disorders

How It Works

Although preliminary studies have shown that coltsfoot contains a substance called “mucilage” that works to coat the throat and is said to soothe the respiratory tract, there are insufficient human studies to show that coltsfoot is safe or effective.

According to Science Direct, coltsfoot works as a respiratory demulcent—an agent that relieves irritation of the mucous membranes in the mouth by forming a protective film.

The action of coltsfoot is thought to be the opposite of that of an expectorant (an agent that helps with the expulsion of thick, productive mucous). Rather, coltsfoot is a relaxing expectorant that acts as a sedative as well as a demulcent, which is good for spastic and irritable coughs of both acute and chronic presentations. The flavonoids also help to reduce inflammation in the bronchioles that make up the lower respiratory tract.

Possible Side Effects

According to Michigan Medicine, from the University of Michigan, “Coltsfoot leaf was originally approved [in Germany] for the treatment of sore throats, but has since been banned in Germany for internal use.” This is due to the discovery that coltsfoot has a high potential for severe side effects.

The primary side effect reported from the use of coltsfoot is liver toxicity. Other possible side effects include:

• Carcinogenicity: A substance that promotes carcinogenesis (the formation of cancer)
• Mutagenicity: A chemical or physical agent's capacity to cause mutations (genetic alterations), which is what is linked to the carcinogenesis of PAs
• Sun sensitivity: More susceptible to sunburn and sun damage of the skin
• Allergic reactions: Hives, skin rash, swelling, wheezing, shortness of breath, or more serious signs and symptoms like nausea and vomiting, severe trouble breathing, weak pulse, seizures, or loss of consciousness

Special Considerations

Coltsfoot is not considered altogether safe for anyone, but the herb should be used with even more caution in specific people. These include:

• Infants or children
• Pregnant women: Coltsfoot is thought to potentially cause birth defects or liver damage
• Breastfeeding moms: As coltsfoot can enter the breastmilk and cause liver damage to the breastfed baby, nursing moms should avoid coltsfoot (including those products that proclaim to be “certified hepatotoxic (liver toxicity) PA-free”
• Those with liver problems: Coltsfoot may worsen liver conditions
• People with allergies to ragweed, chrysanthemums, marigolds, daisies, or related plants
• Individuals with high blood pressure
• Those with heart disease
• People with bleeding disorders

Contraindications

There are no well-documented cases of coltsfoot producing interactions with other drugs or supplements, although some sources suggest using caution with coltsfoot when taking medications such as the following:

• Anticoagulants: Coumadin (warfarin), heparin, Motrin (ibuprofen), Anaprox (naproxen), or other blood thinners such as aspirin. Coltsfoot may increase blood clotting time and cause a higher risk of bruising and bleeding when taken with anticoagulants.
• Antihypertensive drugs: Capoten (captopril), Vasotec (enalapril), Cardizem (diltiazem), Norvasc (amlodipine), HydroDiuril (hydrochlorothiazide), Lasix (furosemide), or other medications for high blood pressure. Coltsfoot may increase blood pressure, lowering the effectiveness of antihypertensive drugs.
• Cytochrome (CYP3A4) inducers: Tegretol (carbamazepine), phenobarbital, Dilantin (phenytoin), rifampin, Mycobutin (rifabutin), and other medications or supplements that break down in the liver, which may increase the liver toxicity potential of coltsfoot.

Anyone who is taking these or any other medications, supplements, or over-the-counter drugs or preparations should consult with their healthcare provider before taking coltsfoot.

Coltsfoot Studies

Several studies have been performed on the efficacy and side effects of using coltsfoot.

Coltsfoot and Carcinogenicity

The Japanese Journal of Cancer published a study that evaluated coltsfoot for its carcinogenicity (cancer-causing properties). The study involved rats, which were separated into four groups, including:

• Group 1: received a 32% coltsfoot diet for four days and then 16% thereafter until the end of the study
• Group 2: received 8% coltsfoot diet for 600 days
• Group 3: received 6% coltsfoot diet for 600 days
• Group 4: received a normal diet without coltsfoot (a control group)

After 600 days, the study findings included the following:

• All the rats in group 1 survived beyond 380 days after the coltsfoot diet feeding, but eight out of 10 rats developed a rare tumor of the liver.
• One in 10 rats developed liver tumors in group 2.
• None of the rats in group 3 developed tumors.

The study authors concluded that the most likely cause of the tumors in the rats was a chemical that was found on the dried flowers—a PA called senkirkine. PAs are toxic to the liver.

A separate study, published in 2010 in the Journal of Applied Toxicology, discovered changes in the DNA (which may be an early indication of cancer) in rat studies were linked with the use of coltsfoot.

This same study also reported that the liver was the primary source of carcinogenic (cancer formation) changes as a result of the use of PAs found in coltsfoot, but that tumors were also found in the lung, kidney, skin, bladder, brain, spinal column, and adrenal glands.

Although there is no clear evidence that points to the fact that PAs cause tumors in humans, the study authors draw a correlation between frequent liver tumors in indigenous peoples in Africa and their consumption of plants containing PAs, such as coltsfoot.

Coltsfoot and Toxicity

A study published in Molecular Medicine Reports discovered several instances of fatal poisoning that occurred due to the use of herbs containing PAs, such as coltsfoot. The study explained that “consumption of cereals and bakery products contaminated with seeds of species containing PAs has been involved in mass poisonings in rural areas of Afghanistan, India, South Africa, and the former USSR.”

Similarly, a 2018 study examined the toxic effects of plants containing PAs. The study reported that the toxic effects of some herbs—including coltsfoot—can cause acute liver disease, resulting in veno-occlusive disease (characterized by an enlarged liver) or in some instances liver cirrhosis. Cirrhosis is a serious condition in which the liver no longer functions properly due to long-term damage.

The study also explains that some PAs, including coltsfoot, have shown genotoxic (causing genetic damage), mutagenic (causing gene mutations), teratogenic (affecting the normal development of the fetus in utero) and carcinogenic (cancer-causing) side effects.

The study authors write, “Research into the presence, identification and quantification of PAs [pyrrolizidine alkaloids] as well as their toxicity is important regarding human consumption of food from plant origin in general and medicinal plants particularly. It is thus important that commercially available beverages (infusions) of plants should be tested for their qualitative and quantitative levels of PAs.”

The PA in coltsfoot has also reportedly caused veno-occlusive disease (a condition involving enlargement of the liver), which was reported in a newborn after the infant’s mother drank tea containing coltsfoot during pregnancy. The liver condition was said to result from the well-known hepatotoxins (substances that are toxic to the liver) contained in coltsfoot.

Selection, Preparation, and Storage

There is not enough clinical research data to support the suggestion of a safe dosage of coltsfoot. The appropriate dose of any supplement, including coltsfoot, should be based on several factors such as weight, age, general health and other factors.

Although herbal products may be natural, that doesn't mean they are necessarily safe, particularly when taken in large doses. Always follow the package instructions and the advice of your healthcare provider.

Preparation

Coltsfoot is commonly made into a tea using the leaves or flowers of the plant. Other preparations include a topical flower compress to treat skin problems such as inflammation.

Some people smoke the herb, said to be effective for respiratory disorders, but the clinical study evidence does not back up the safety or efficacy of smoking coltsfoot. In addition, the safe and effective use of coltsfoot in a tea or to treat skin problems is not backed up by scientific evidence.

What to Look For

Because herbal supplements are not regulated by the Food and Drug Administration (FDA) or any other governmental regulatory entity in the United States, it’s important that you do your due diligence to ensure you're getting a safe, hepatotoxic PA-free product.

The products that are certified should be clearly labeled as being hepatotoxic PA-free.

Common Questions

Can a person smoke coltsfoot?

Yes. Coltsfoot is said to have a neutral/light flavor and has been thought to help soothe the throat and respiratory tract when smoked. However, smoking coltsfoot could result in a harsh cough, particularly when used in a high concentration in blends for smoking.

Is coltsfoot safe to use in a tea for a child’s cough?

No. Coltsfoot is never considered safe for use in infants or children. There is insufficient clinical research evidence that shows safety or efficacy of the herb, and due to its well-known side effects such as liver toxicity, it should not be used by children.

Can coltsfoot be used on the skin?

Yes. The flowers of the herb have been made into a poultice to treat some skin conditions, but there is lack of sufficient scientific evidence from clinical research studies to back any claims of safety or efficacy in the topical use of coltsfoot.

A Word From Verywell

Although there are limited human studies involving the safety and efficacy of coltsfoot, some reliable scientific evidence points to the probability that the herb does have some medicinal value such as its ability to soothe the respiratory tract. However, due to the high risk of serious side effects, such as liver toxicity, it may be advantageous to explore other natural and herbal supplements with similar benefits.

Other herbal supplements known to help soothe a chronic cough include marshmallow (Althaea officinalis) root and leaves and other members of the mallows (Malvaceae) family, slippery elm (Ulmus spp.), and other demulcent herbs.  Most importantly, always consult with a healthcare provider before taking coltsfoot or any other herbal supplement.