In my country (Poland) Coltsfoot was always very popular cough remedy (used only seasonally) and obviously nobody had any liver problems as a result of taking it internally. Unfortunately, only few people now use it due to some animal studies that seem to proof the herb can damage liver and lead to live cancer. But, when you look at the study details (below) you will see those pseudo scientists were feeding rats with huge amounts of this herb for almost 2 years!!! leading to liver cancer. But smaller concentration didn’t cause the problem (even after 2 years!!!).
There are many herbs and even foods that used in mega doses can cause liver problems but used in normal amounts are safe. Can you imagine what would happen if they gave those rats 32% paracetamol diet for 2 years (Paracetamol overdose is one of the leading causes of liver failure) but the drug is allowed for regular internal use and extremely popular.
This website (https://www.webmd.com/vitamins/ai/ingredientmono-730/coltsfoot), like many other sites promoted by google, is sponsored by big pharma and they always exaggerate the potential side effects of herbal remedies, although in reality they are insignificant or none if herbs are used properly.
In herbal formulas and teas the there concentration of Pyrrolizidine alkaloids is so tiny that there is no reason to even talk about its safety. In addition, Coltsfoot is used for only one or few weeks (to easy cough, cold, flu, or sore throat) and not for 2 years like in that unfortunate animal study!!!
Some sources even suggest Pyrrolizidine alkaloids are present only in the raw herb but in teas and tinctures they are not found or present in very small concentrations.
COLTSFOOT AND CARCINOGENICITY STUDY
The Japanese Journal of Cancer conducted a study to evaluate coltsfoot for its carcinogenicity (cancer-causing properties). The study involved rats, which were separated into four groups, including:
- Group one – which received 32% coltsfoot diet for four days then, 16% thereafter until the end of the study.
- Group two – which received 8% coltsfoot diet for 600 days.
- Group three – which received 6% coltsfoot diet for 600 days.
- Group four – which received a normal diet without coltsfoot (a control group)
After 600 days the study findings included:
- All the rats in group one survived beyond 380 days after the coltsfoot diet feeding, but eight out of 10 rats developed a rare tumor of the liver.
- In group two, only one in 10 rats developed liver tumours.
- None of the rats in group three developed tumours.
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 pyrrolizidine alkaloid called senkirkine.1 Pyrrolizidine alkaloids are toxic to the liver.
TRADITIONAL USE AND HEALTH BENEFITS
Coltsfoot (Tussilago farfara) name refers to the shape of the leaves resembling a horse’s foot.
Coltsfoot is often mistaken for dandelion because of the similarity of the flowers which have a striking resemblance to each other. The herb also has a similar character to the dandelion being considered a weed and growing by roadsides, in waste land, hedgerows and meadows.
The herb has been commonly used as a remedy for sore throats and coughs. The Latin name for Coltsfoot (Tussilago farfara) has derived from the two words, Tussil meaning ‘cough’ and ago meaning ‘depart’.
Scientific studies have shown that Coltsfoot contains a significant amount of a substance called mucilage. This substance then coats the throat and effectively soothes the respiratory tract. It is thought that this herb has an excellent effect against Asthma, sore throat, wheezing, bronchitis and laryngitis.
The great herbalists of antiquity such as Dioscorides and Phiny recommended smoking the herb to help the throat. Although this practice probably won’t help the throat to heal, smoking Coltsfoot is still thought to be a good substitute to smoking tobacco.
Other uses have been recorded where Coltsfoot has been applied as a topical balm to the skin. Using a poultice of flowers, Coltsfoot was traditionally applied to the skin to treat skin problems such as inflammation, eczema and stings.
Usually Coltsfoot herb (leaves or flowers, sometimes by decoction) is made into a tea. Other uses include smoking the herb and making a flower poultice to treat skin conditions.
Apparently in 18th century France every well respected apothecary used a picture of the Coltsfoot flower as a symbol of their trade; this shows the popularity of the herb during this time in Europe. When Coltsfoot reached the Americas a popular practice would be to soak a blanket in a solution of Coltsfoot and wrap it around patients suffering from whooping cough.
Most of the most common folklore concerning Coltsfoot comes from the fact that it has always been used as a smoking herb. Internally and externally Coltsfoot has been used through the centuries to bring about an effect that can be thought of as medicinal. Not only did Dioscorides, Galen, Pliny and Boyle recommend the herb to be smoked but in certain magical rituals Coltsfoot is burned to create equilibrium or to call a loved one back. Cornish tin miners would regularly smoke Coltsfoot to guard against diseases of the lungs.
One of the most interesting folklores from Northern England tells how Coltsfoot leaves were used to tell the future. By peeling away the thin layer of soft grey tissue of the new leaf, the shiny surface of the leaf would be used as a window or mirror. It is said that with the right charm or utterance the ‘window’ would then show you the future or your future spouse. This particular folklore is now only known by memory and the chants that were kept secret to locals have faded into obscurity.
Flavonoids, approximately 8 per cent mucilage comprising polysaccharides, pyrrolizidine alkaloids, about 10 per cent tannins, zinc and vitamin C. The pyrrolizidine alkaloids are hepatotoxic; However, they are generally obliterated when the herb is boiled to prepare a decoction.
Do not exceed 10g a day when taking Coltsfoot as a tea. Not recommended for children and infants. Do not use during pregnancy. Do not use if you suffer from heart disease, liver disease or high blood pressure.
A study published in Molecular Medicine Reports discovered several instances of fatal poisoning that occurred due to the use of herbs containing pyrrolizidine alkaloids (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.”3
Similarly, a 2018 study examined the toxic effects of plants containing pyrrolizidine alkaloids. 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.3 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 (may cause genetic damage), mutagenic (may cause gene mutations), teratogenic (may affect 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.”3
The pyrrolizidine alkaloid 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.4 The liver condition was said to result from the well-known hepatotoxins (substances that are toxic to the liver) contained in coltsfoot.
- Hirono I, Mori H, Culvenor CC. Carcinogenic activity of coltsfoot, Tussilago farfara. The Japanese Journal of Cancer Research; 7(1):125-9.
- Chen T, Mei N, Fu PP. Genotoxicity of pyrrolizidine alkaloids. Journal of Applied Toxicology.2010;30:183–196. doi:10.1002/jat.1504
- Seremet O, Olaru O, Maria Gutu C, et al. Toxicity of plant extracts containing pyrrolizidine alkaloids using alternative invertebrate models. The Journal of Molecular Medicine Reports. 2018;17(6): 7757–7763. doi:10.3892/mmr.2018.8795
- Dasgupta A, Sepulveda J. Accurate Results in the Clinical Laboratory: a Guide to Error Detection and Correction. Pages 75-92. Amsterdam: Elsevier; 2013. doi:10.1016/C2011-0-04380-6