Comfrey: Revered by Folk Healers, Banned by Western Medicine – The Truth Behind This Medicinal Plant

Comfrey is one of the very best herbs for healing and soothing damaged or irritated tissues (photo by Michael Vertolli, RH)

When European settlers came to Canada, out of necessity they often came with very few possessions. They could only bring what was most valuable to them. Once they arrived, most of them had to grow their own food. Knowing that there would be a limited availability of seeds for planting in their new home, they often brought seeds of some of their favorite foods and herbs with them.

One of the most revered of medicinal herbs that they brought to Canada was comfrey (Symphytum officinale). This valuable herb continues to be popular to this day even though some toxicity concerns have come to light in recent decades.

Comfrey is a perennial herb that is easily grown in a variety of conditions. It prefers moist (but not wet) soil and can tolerate full sunlight to almost complete shade, but it grows best when it gets sun about half to two thirds of the daylight hours. All parts of the plant have been used medicinally.

Comfrey is a common garden herb and is well adapted to our climate. It is a native of much of Europe and has naturalized in many other parts of the world including much of temperate North America where it occasionally escapes into the wild, but it is not that common in Ontario. It is still mostly grown rather than wild harvested. This is fortunate because comfrey can become locally invasive in areas where it was once planted, especially in river valleys.

The Toxicity Debate

Anyone who is familiar with comfrey is probably aware of the toxicity concerns that have been widely publicized in the literature since the 1980s. Comfrey contains constituents called pyrrolizidine alkaloids that are extremely toxic to the liver. The debate regarding what this means about the toxicity of the herb itself has been quite intense with extreme opinions on both sides.

Some people believe that comfrey is completely safe based on the fact that it is a very popular herb and has been consumed for centuries – probably by millions of people – with very little evidence of toxicity.

On the other side there are those – usually people who subscribe to a more reductionistic medical philosophy – who believe that the research clearly indicates that comfrey is too toxic to use internally. As a result, many books on herbs that have been published in recent years no longer include it. If they do, they generally mention it from a historical perspective and suggest that the plant is too toxic to be used.

In most countries – including Canada – products containing comfrey are not allowed for sale for internal use, but they are allowed for sale in external preparations as long as they are only recommended to be used for short periods of time in situations where a person's skin is not broken.

As always, the truth lies somewhere in the middle and these restrictions are excessive. In most cases comfrey is quite safe for use topically if the skin is broken and internally as well if we follow some basic precautions. I will discuss these precautions later, but I mention it now because it affects the way the herb is harvested.

Aspects and Types of Comfrey

The first thing to know is that there are actually three different kinds of comfrey that you might come across. Common comfrey (Symphytum officinale) is the only species that I recommend for medicinal use because it has the lowest level of pyrrolizidine alkaloids. Prickly comfrey (Symphytum asperum) and Russian comfrey (Symphytum x uplandicum), which is actually a cross between common comfrey and prickly comfrey, contain higher levels of the toxic alkaloids with Russian comfrey containing the most. It can be difficult to differentiate common, prickly, and Russion comfrey and it's important to be aware that when you come across wild populations it could be any of these species.

When you purchase products containing comfrey there is no way of being certain what species you are getting as they are often mixed or misidentified. I therefore only recommend that you use common comfrey that you have grown yourself and have obtained the seeds or seedlings from a reputable source that can guarantee the correct species.

In addition to using the correct species, it is also important that you use the safest part of the plant. All parts of the plant have been used medicinally, but different parts have different levels of toxicity. The roots and young spring leaves contain the highest levels of pyrrolizidine alkaloids and should not be used. However, the level of alkaloids decreases in the aerial parts of the plant as it matures and I recommend that comfrey only be harvested once the plant begins to flower. By that time the leaves should contain a significantly lower level of alkaloids.

Harvesting and Using Comfrey

In Ontario, comfrey usually begins to flower between mid May and early June. It may flower later further north or when it is growing in locations where it’s in shade most of the day. The leaves can be harvested from the beginning of its flowering period until late July. I usually pick the top 30-40% of the plant a week or two after it begins to flower which is typically in the first week of June where I live north of Toronto.

You can dry comfrey by hanging the harvested portion in a warm, dry, well-ventilated area. Remove the leaves and flowers from the stock when they are completely dry and store them in an air-tight container. Plastic bags are not good enough to maintain it's potency.

Tinctures for Internal Use

You make a tincture from either the fresh or dried herb using 30 to 40% alcohol. To make a tincture of the fresh herb, remove the leaves and flowers and discard the bottom half of the main stock; chop the herb very fine and fill your jar to the top. This will give you approximately a 1:5 potency fresh herb tincture (that means that there is one gram of herb in every 5 ml of tincture). It is best to use an amber wide-mouthed jar. Fill it up with your alcohol to 1/2 cm from the top and shake it vigorously.

During the first week the level of liquid will drop as it fills in air spaces in the plant tissues. After 1 to 2 weeks open it up and top it up again to 1/2 cm from the top. Store it in the dark and don’t open it again until you are ready to press it. Your tincture should be shaken once or twice a day for the first couple of weeks and again for about a week before you press it.

It is preferable not to make oil-based preparations such as infused oils or ointments from the fresh herb. Comfrey contains too much water and nitrogen and oil-based preparations will often go moldy unless they are made from the dried herb.

Photo by Michael Vertolli, RH

Poultices, Salves, and Oils for External Use

Comfrey is one of the very best herbs for healing and soothing damaged or irritated tissues. It can be applied topically as a poultice, compress, or ointment for cuts, scrapes, bites, stings, burns, rashes or almost any other skin irritation. It is also beneficial for varicose veins and hemorrhoids. It soothes the skin, stops bleeding, reduces inflammation and pain, and promotes healing.

It is preferable not to make oil-based preparations such as infused oils or ointments from the fresh herb. Comfrey contains too much water and nitrogen, so oil-based preparations will often go moldy unless they are made from the dried herb. An infused oil is made in a similar manner to a tincture except that we extract comfrey in oil. The oils that are primarily monounsaturated, such as olive oil, are used for this purpose because they are more resistant to rancidity and are liquid at room temperature. You can also add a bit of vitamin E which helps to further protect the oil from rancidity and adds healing properties of its own.

To make: Half fill your bottle first with chopped (but not ground) dried comfrey. Then fill the bottle to 1/2 cm from the top with oil. Your oil infusion should be shaken in a similar fashion to making a tincture, and kept in the dark at room temperature. Allow it to infuse for at least a month.

Press and filter it when you are ready to use it. You can use the comfrey infused oil as is, or make it into an ointment by gently heating the oil just enough to melt beeswax and then allow it to cool and congeal. Never heat the oil so that it starts to simmer. It doesn't take very much heat to melt beeswax.

Comfrey can also be used as a poultice by either grinding up the fresh herb or chopping up the dried herb and adding just enough boiled water so that it is moist but not runny. This can be applied directly to your skin, but it’s best to put a couple of layers of gauze under the poultice to keep herb particles from entering the open wound and to make it easier to lift the poultice when you are done. The more serious the wound or injury, the longer the poultice should be applied. Allow any remaining liquid to dry on your skin afterwards.

Caution: One caution concerns using comfrey on deep wounds or surgical incisions. This is because it is important that with deeper wounds the deeper tissues either heal more quickly or at approximately the same rate as the surface tissues. If the surface tissues heal much more quickly than the deeper tissues it can sometimes result in an abscess. Comfrey is such an effective healing herb and it will sometimes promote much quicker healing at the surface where the herbal application is more concentrated. For deeper wounds it might be best to hold off on the comfrey until the wound has healed a bit first.

Comfrey is also very beneficial for deeper tissue injuries such as bruises, strains and sprains and is probably the best herb I know for healing broken bones. For deeper tissue injuries it is best to initially use comfrey in the form of a poultice (because it is more concentrated) and then switch to an infused oil or ointment (because they are more convenient) after the symptoms have significantly improved.

For broken bones, it is preferable to also use comfrey internally as a tea or tincture. However, healing bone fractures is a long process, generally longer than it is recommended to use comfrey internally. Fortunately, it can also be used in a homeopathic potency for this purpose, which is completely safe.

I recommend taking a tea or tincture formula containing comfrey three times per day and also taking the 200C potency of Symphytum once a day for the first week or two after the fracture occurs. Then stop taking the tea or tincture but continue taking the homeopathic Symphytum until the fracture is completely healed. Do not use comfrey in any form until the fracture has been properly set.

It will not be possible to use the herb topically when a non-removable cast is required. Nevertheless, it will still be beneficial to use an external preparation for a few weeks after the cast is removed.

More Medicinal Uses for Comfrey

Comfrey is one of the most soothing and healing herbs for the mucus membranes of our mouth and digestive tract. It can be used for any kind of irritation or inflammatory condition of these tissues including inflamed gums, sore throats, laryngitis, ulcers, irritable bowel syndrome, colitis, diverticulitis and diarrhea. For bowel inflammation, such as colitis, it is best to use comfrey once per day as an enema as well, because many of its healing constituents will be absorbed further up in the digestive tract and not make it to the colon.

Comfrey is also an excellent herb for the lungs. It can be used for any condition characterized by a cough, especially a dry cough. It is great for chest colds, bronchitis, asthma and other acute and chronic lung conditions.

Notes on Using the Plant Safely

Now that I’ve covered the major uses of comfrey, let’s get back to the issue of toxicity. Most of the concerns result from studies that can not easily be extrapolated to the normal use of the herb by people because most of the studies involved giving isolated pyrrolizidine alkaloids to rodents, or adding comfrey to their diet in very large amounts.

However, there have been some cases of liver toxicity in humans, sometimes severe. In these cases the herb was always being used by people who are at high risk for pyrrolizidine alkaloid toxicity or more typically were using comfrey in excessively large doses for long periods of time. To complicate matters, it was not always clear what species of comfrey they were consuming. To keep things in perspective, it is important to realize that for every genuine case of toxicity from the use of this herb there have been tens, if not hundreds of thousands of people that have used it safely and benefited from it's amazing healing properties.

In order to benefit from comfrey without any risk of toxicity it is necessary to observe the following precautions:

(1)   Only use the mature leaves or herb of common comfrey (Symphytum officinale). Do not use any other parts of the plant or species.

(2)   Only use comfrey in combination with other herbs. Do not exceed 20% of formulations for internal use, or 40% of formulations for external use.

(3)   Only use formulations containing comfrey up to three internal doses or external applications per day for a maximum of one to two months for internal use, or two to three months for external use. It is OK to use it if your skin is broken.

(4)   Comfrey should not be used—internally or externally—by pregnant or nursing women, or by infants under the age of one.

(5)   Comfrey should not be used internally by children under the age of three, seniors over the age of 70, or anyone with a serious liver condition or who is suffering from a serious long-term chronic health condition.

You might ask: with all of these concerns about toxicity, why use comfrey at all and use other herbs instead? In my own practice, for most conditions for which comfrey is recommended—usually even for lung conditions—I do prefer to use other, safer herbs. There isn't any point using an herb for which there is potential toxicity when there are other herbs that work just as well for which there are no concerns. But for healing irritated, inflamed or damaged tissues, and especially bone fractures, comfrey is one of the most beneficial herbs and it's benefits far outweigh it's risks (which are practically non-existant if you observe the precautions indicated above).

Nature has provided us with many medicinal gifts. However, all that is natural is not necessarily always completely safe. It is important that we use these gifts with wisdom, caution and respect. If we do, the healing possibilities are endless!

Michael Vertolli is the founder of the Living Earth School of Herbalism. To see their latest postings visit:  https://www.facebook.com/LivingEarthHerbalism