External Use of Comfrey

The Internal Use of Comfrey

I don't get asked about the safety of internal use of comfrey much any more.  I think most people have heard the pyrrolizidine alkaloids found in many comfreiy products are problematic, and that we should be cautious about internal use of comfrey, or not use it at all. There are a few who still throw caution to the wind and simply use it willy nilly as much as they wish. However, I would not suggest that for everyone. Especially if someone already has a compromised liver or compromised vasculature.

The issue is that many people who are compromised do not know it, and even worse, you don't have to have a compromised liver or vasculature for pyrrolizidine alkaloids to cause hepato veno-occlusive disease. We do know that there have been incidents of hepato veno-occlusive disease caused by pyrrolizidine containing plants, in both animals and humans. I choose to be cautious myself and do not suggest others use any of the pyrrolizidine containing herbs internally usually. They really need to be studied more thoroughly as we have a lot of unanswered questions about pyrrolizidine alkaloids and the plants that contain them.

The External Use of Comfrey

Even though I get few questions on internal use of comfrey, I still get a fair number of questions about external use of comfrey. So, I thought I would write up a short article for anyone with this question. I personally have no qualms about using it on my own skin even if I have an open wound, as long as the wound is completely clean. (I would never use comfrey on a wound that is not completely clean as it will quickly heal right over the filth and get infected.)  However, I do not recommend it to others on closed wounds any more either. Even if I wanted to do so,  it would be considered unethical by my medical board since the FDA has deemed it illegal to use on broken skin or mucous membranes.

I myself usually use Calendula succus in the same situations one might use Comfrey externally. Calendula salve or fresh Aloe both are great for wounds.   I find fresh Aloe and my faithful friend Calendula usually work as well as comfrey ever did. I often turn to a leaf of fresh Aloe which I can easily pick off my house plant. It is quick to access it. It has the same allantoin constituent that is found in Comfrey that is known to speed up healing through increased cellular division. (I understand that maggots make allantoin too.) I have not thrown out Comfrey for my personal use on wounds but as far as recommending it for general public use on open skin or mucous membranes, I would have to say I would not recommend it. It could indeed be absorbed into the blood stream and end up causing trouble for one person when it caused absolutely no trouble for many other people. This would especially be likely if it was used repetitively. One of the reasons I use it on myself without being concerned is that I have a past history of using it that way on myself before we knew about the issues with pyrrolizidine alkaloids. If I had never used it previously and I did not know how I would react to it, I would be more hesitant to use it.

There are legal rules around selling comfrey. It is important for people selling Comfrey products to know that the FDA does not allow it to be sold for internal use or use on open skin or mucous membranes unless the pyrrolizidine alkaloids are removed. Some companies do remove them and therefore you can find Comfrey being sold with low levels of pyrrolizidines sometimes.

For those who want more details on  the pyrrolizidine alkaloids in comfrey, I will end this by including a short write up below, from something I wrote years ago when the pyrrolizidine scare first came up.

Everyone has heard about Comfrey and the concern about the pyrrolizidine alkaloids in Comfrey causing hepato veno-occlusive disease (HVOD). The liver changes the pyrrolizidines into potent alkylating agents that react rapidly with cell constituents resulting in cellular destruction or abnormal cell growth patterns. Accumulation of this cellular damage is known as HVOD. Research needs to be completed with comfrey and the prevelence of HVOD. Some of the cases that exist are sketchy but give reason for us to act cautiously. What most people don’t seem to realize is there are other medicinal herbs that also contain toxic pyrrolizidine alkaloids. The FDA has made it illegal to sell any of them for internal consumption. These herbs are Alkanna tinctoria (Alkanet), Anchusa officinalis (bugloss), Borago officinalis (borage), Crotalaria spp., Cynoglossum spp., Erechtites heiraciifolia, Eupatorium cannabium (hemp agrimony), Eupatorium purpureum (gravel root), Heliotropium spp., Lithospermum officinale (European gromwell), Packera candidissima, Petasites spp., (e.g., butterbur), Pulmonaria spp., (e.g. lungwort), Senecio jacobea (European ragwort), Senecio vulgaris (groundsel herb), Symphytum spp., (comfrey), and Tussilago farfara (coltsfoot).

Some growers grow pyrrolizidine free Comfrey. Some manufacturers offer pyrrolizidine free  Comfrey products. Some species of comfrey are known to contain more pyrrolizidine alkaloids than others. Symphytum officinalis appears to contain less than Symphytum uplandicum. However, Symphytum uplandicum has been sold as Symphytum officinalis in the past and the purchasers have not been aware they were buying the incorrect species. The  Comfrey leaves contain less alkaloid than the root generally and plants that do not go through the full winter season are thought to contain more of the alkaloid than comfrey that that lives in regions with a winter where the leaves die back. It also appears that repeat harvest or other damage to the plant will increase the pyrrolizidine alkaloids in the plant. However, I would add that the research I have read is conflicting.

Comfrey has been used widely in the past. Animals have been fed comfrey to improve their health and to increase their productivity. Chickens fed comfrey have been known to lay more eggs while comfrey fed cows gave more milk.

This does not mean that animals were not harmed by it. Having raised various farm animals and having friends with farms, I know that animals can die with no known cause. Slowly or suddenly an animal can die without the farmer knowing why and without any type of autopsy to find out the cause. So, we can't really say that animals have been fed comfrey without it causing harm since many people never know the exact reason for a death of a farm animal unless it is obvious.