THE BENEFITS OF THE USE OF COMFREY
IN HERBAL PREPARATIONS
CONTRA-INDICATIONS OF COMFREY
IN HERBAL PREPARATIONS
CONTRA-INDICATIONS OF COMFREY
COMFREY
by Sabrina G. Seitz, RN
by Sabrina G. Seitz, RN
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There have been a few reports linking comfrey use and symptoms of hepatoxicity. It was from these reports that the FDA came to its final conclusion and decided comfrey was unsafe and should be strictly regulated. In reviewing these reports, how they came to this conclusion is not easily seen.
The first report of an adverse reaction from comfrey use was in 1985. A 49 year old women consumed an estimated 14.1 mcg comfrey alkaloids/kg of body weight each day in the form of comfrey-pepsin tablets for four months prior to being admitted to the hospital with veno-occlusive disease (VOD). This condition involves the destruction or obliteration of small hepatic veins leading to cirrhosis and eventually liver failure, if untreated. What was not considered in the report was that the woman was also taking other drugs including the hepatotoxin, acetaminophen. Also, she had been consuming a tea for the previous six months that contained PA’s from an unidentified source. This greatly increased her level of exposure to PA’s. The woman was followed for seven years afterwards with no recurrence of her symptoms, but there were questions regarding other unreported drug use.
The second report occurred in 1987, involving a 13 year old boy diagnosed with Crohn’s disease three years before presenting with acute VOD. The boy had intermittently been using prednisolone (a steroid) and sulphasalazine (a known hepatotoxin) , both powerful anti-inflammatory drugs. He was also taking infusions of comfrey leaf and root teas in unknown amounts. He was treated and had good response.
The third report was in 1989 when a woman presented with complaints of abdominal pain, fatigue and allergies. She was found to be consuming up to 10 cups of comfrey tea per day and comfrey pills and had been doing so for over a year. It was not until eight years later that she was diagnosed with VOD induced by PA’s. No potentiating drug was connected.
A fourth case was in 1990, involving a 23 year old Australian man who reportedly was eating four to five young comfrey leaves per day for two weeks before onset of symptoms. He was diagnosed with rapidly progressive VOD and soon died. This is the only fatality reported that I could find. The reporting doctors believed that his severe reaction may have been due to a protein deficiency, as his levels of comfrey fell within the therapeutic range of use.
In a fifth report in 1992, a 77 year old UK woman associated the use of 1/3 teaspoon of comfrey root per day to her elevated liver enzymes and bilirubin. There was no ascites or hepatomegaly. This did not follow the symptom pattern that was typical of PA poisoning and may have been associated with other herbal compounds. Therefore, her condition was not likely induced by comfrey ingestion.
There have been other reports of PA toxicity, but they have been attributed to accidental exposure from dangerous PA-containing weeds that contaminate cereal crops and grazing lands. These are plants like Heliotropium, Senecio and Crotalaria which have caused poisonings in India, Afghanistan and South Africa among other places. Comfrey does not belong in this group, but, unfortunately it has been lumped in with the worst.
In all these reports, there were other confounding circumstances that indicated malabsorption disorders, and possible other hepatotoxic drug use/abuse. There was the presence of other illnesses in most cases and taken together, these reports fail to demonstrate a clear link between consumption of comfrey and VOD. In researching this topic, I came across article after article that parroted the statement that “there are abundant human case studies” showing poisonings. It was very difficult to find these original reports and studies and, in the end, I only found five; all of which had questionable conclusions. To extrapolate that comfrey is hepatoxic, based on so little evidence, is just poor science. I daresay that if the prescription drugs on the market today were evaluated in the same manner as comfrey and labeled toxic from such little data, there would not be many left.
I did find a reference to a study done by Dr. Clare Anderson from the Laboratory of Pharmakinetics and Toxicology in London that was testing 40 long-term comfrey consumers, who then submitted to liver function tests. All those studied were found to have perfectly normal livers. I was unable to find the actual study, but I’m sure that this kind of information is not welcome by regulatory bodies e.g. the FDA and the FTC.
Nevertheless, as it stands now, the FDA is requiring that comfrey be eliminated from any internal teas or formulas. It must be clearly labeled for “external use” only and disclaimers added that say comfrey contains toxic PA’s that can cause liver toxicity. Most herbalists know that comfrey is safe when used appropriately and do not hesitate taking it themselves. It seems that with the continued use of comfrey, despite FDA restrictions, there would be more reports of toxicity if, in fact, there was a connection.
In the interest of safety, when there is suspected liver disease or “weakness”, it is best to harvest the more mature leaves, as they contain far less PA’s than do the roots and young leaves.. There continues to be no reports of adverse reactions in the use of comfrey externally, so no precautions for harvesting are given.
The first report of an adverse reaction from comfrey use was in 1985. A 49 year old women consumed an estimated 14.1 mcg comfrey alkaloids/kg of body weight each day in the form of comfrey-pepsin tablets for four months prior to being admitted to the hospital with veno-occlusive disease (VOD). This condition involves the destruction or obliteration of small hepatic veins leading to cirrhosis and eventually liver failure, if untreated. What was not considered in the report was that the woman was also taking other drugs including the hepatotoxin, acetaminophen. Also, she had been consuming a tea for the previous six months that contained PA’s from an unidentified source. This greatly increased her level of exposure to PA’s. The woman was followed for seven years afterwards with no recurrence of her symptoms, but there were questions regarding other unreported drug use.
The second report occurred in 1987, involving a 13 year old boy diagnosed with Crohn’s disease three years before presenting with acute VOD. The boy had intermittently been using prednisolone (a steroid) and sulphasalazine (a known hepatotoxin) , both powerful anti-inflammatory drugs. He was also taking infusions of comfrey leaf and root teas in unknown amounts. He was treated and had good response.
The third report was in 1989 when a woman presented with complaints of abdominal pain, fatigue and allergies. She was found to be consuming up to 10 cups of comfrey tea per day and comfrey pills and had been doing so for over a year. It was not until eight years later that she was diagnosed with VOD induced by PA’s. No potentiating drug was connected.
A fourth case was in 1990, involving a 23 year old Australian man who reportedly was eating four to five young comfrey leaves per day for two weeks before onset of symptoms. He was diagnosed with rapidly progressive VOD and soon died. This is the only fatality reported that I could find. The reporting doctors believed that his severe reaction may have been due to a protein deficiency, as his levels of comfrey fell within the therapeutic range of use.
In a fifth report in 1992, a 77 year old UK woman associated the use of 1/3 teaspoon of comfrey root per day to her elevated liver enzymes and bilirubin. There was no ascites or hepatomegaly. This did not follow the symptom pattern that was typical of PA poisoning and may have been associated with other herbal compounds. Therefore, her condition was not likely induced by comfrey ingestion.
There have been other reports of PA toxicity, but they have been attributed to accidental exposure from dangerous PA-containing weeds that contaminate cereal crops and grazing lands. These are plants like Heliotropium, Senecio and Crotalaria which have caused poisonings in India, Afghanistan and South Africa among other places. Comfrey does not belong in this group, but, unfortunately it has been lumped in with the worst.
In all these reports, there were other confounding circumstances that indicated malabsorption disorders, and possible other hepatotoxic drug use/abuse. There was the presence of other illnesses in most cases and taken together, these reports fail to demonstrate a clear link between consumption of comfrey and VOD. In researching this topic, I came across article after article that parroted the statement that “there are abundant human case studies” showing poisonings. It was very difficult to find these original reports and studies and, in the end, I only found five; all of which had questionable conclusions. To extrapolate that comfrey is hepatoxic, based on so little evidence, is just poor science. I daresay that if the prescription drugs on the market today were evaluated in the same manner as comfrey and labeled toxic from such little data, there would not be many left.
I did find a reference to a study done by Dr. Clare Anderson from the Laboratory of Pharmakinetics and Toxicology in London that was testing 40 long-term comfrey consumers, who then submitted to liver function tests. All those studied were found to have perfectly normal livers. I was unable to find the actual study, but I’m sure that this kind of information is not welcome by regulatory bodies e.g. the FDA and the FTC.
Nevertheless, as it stands now, the FDA is requiring that comfrey be eliminated from any internal teas or formulas. It must be clearly labeled for “external use” only and disclaimers added that say comfrey contains toxic PA’s that can cause liver toxicity. Most herbalists know that comfrey is safe when used appropriately and do not hesitate taking it themselves. It seems that with the continued use of comfrey, despite FDA restrictions, there would be more reports of toxicity if, in fact, there was a connection.
In the interest of safety, when there is suspected liver disease or “weakness”, it is best to harvest the more mature leaves, as they contain far less PA’s than do the roots and young leaves.. There continues to be no reports of adverse reactions in the use of comfrey externally, so no precautions for harvesting are given.