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Revered by Folk Medicine, Banned by Medical Experts, What is the Real Truth About this Powerful Medicinal Plant?

When European settlers came to Canada, out of necessity they often carried few possessions. So they could only bring what was most dear to them. Once they arrived, most of them had to become farmers, if they weren’t already. Knowing that there would be a limited availability of seeds for planting in their new home, they often brought seeds of some of their favourite vegetables and herbs with them. One of the most revered of medicinal herbs that was brought to Canada and planted by these settlers was comfrey (Symphytum officinale). This valuable herb continues to be popular to this day, in spite of some of the toxicity concerns that have come to light in the last two decades.

Comfrey is a perennial herb easily grown in a variety of conditions. It can tolerate full sunlight to almost complete shade, but it grows best when it gets sun for about one half to two thirds of the daylight hours. The young leaves have been eaten in salads and used as a pot herb, and all parts of the plant can be used medicinally. Comfrey has been widely planted and is well adapted to our climate. It occasionally escapes into the wild, but it is not that common in Ontario. Today it is still mostly grown rather than wild harvested.

Anyone who is familiar with comfrey is probably aware of the recent toxicity concerns that have been widely publicized in the literature. Comfrey contains substances called pyrrolizidine alkaloids. These constituents are extremely toxic to the liver. The debate about what this means about the toxicity of the herb itself has been quite heated, with extreme opinions on both sides. Some people believe that comfrey is completely safe, pointing to the fact that comfrey is one of the most popular herbs 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 medical philosophy — who believe that the research clearly indicates that comfrey is too toxic to use internally. Many people have become so uptight about the use of comfrey that the majority of books on herbs that have been published in recent years don’t even include it. If they do, they generally mention it from a historical perspective and indicate that the plant is too toxic to be used.

As always, the truth lies somewhere in the middle. In spite of that, most regulatory authorities have sided with the medical “experts” and comfrey has been banned for internal use in most countries in recent years. In Canada, it is only allowed for sale in external preparations for use if the skin is not broken. These restrictions are way off the mark! In most cases comfrey is quite safe for use 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.

The first thing you need to know is that there are actually three different kinds of comfrey. Common comfrey (Symphytum officinale) is the only species that I recommend for medicinal use because it has the lowest level of pyrrolizidine alkaloids and it doesn’t contain some of the most toxic alkaloids. Prickly comfrey (Symphytum asperum) and Russian comfrey (Symphytum xuplandicum), which is actually a cross between common comfrey and prickly comfrey, contain larger quantities and more toxic alkaloids. Russian comfrey is the most toxic.

When you purchase products containing comfrey, there is no way of knowing what species you are getting. The species 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 (such as Richter’s Herbs) that can guarantee the correct species.

In addition to using the correct species, it is also important that you use the correct part of the plant. All parts of the plant have been used medicinally, but different parts of the plant have different levels of toxicity. The root contains the highest levels of pyrrolizidine alkaloids and should not be used. The very young leaves are also relatively toxic. They contain approximately 1/10 the level of alkaloids as the root, with this level decreasing as the plant matures. I recommend that comfrey only be harvested once the plant begins to flower. By that time the leaves should not contain more than 1/50 to 1/100 the level of alkaloids of the root.


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 is in the shade most of the day. The leaves can be harvested from the beginning of its flowering period until mid August. I prefer to pick the top 40% of the plant a week or two after it begins to flower.

You can hang the plant in a warm, dry, well-ventilated area to dry. Remove the leaves and flowers from the stock when they are completely dry and store them in an air-tight container (plastic bags will not do).

You can also chop up the fresh herb when you harvest it and make a tincture using 30-40% alcohol. Remove the leaves and discard the bottom half of the main stock, chop the herb very fine and fill your bottle to the top, then pack it down and force in a bit more herb. 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 a dark-coloured wide-mouthed bottle. Fill it up with your alcohol to 1/2 centimetre from the top and shake it vigorously. After a couple of hours the level of alcohol will drop. Open it up and top it up again then don’t open it 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.

Never make oil-based preparations such as infused oils or ointments from the fresh herb. Comfrey contains too much water and oil-based preparations will go moldy unless they are made from the dried herb.

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 promotes healing.

Comfrey is also beneficial for deeper tissue injuries such as bruises, strains and sprains. It is probably the best herb I know for healing broken bones. For deeper tissue injuries it is best to use comfrey in the form of a poultice.

For broken bones, it is preferable to also use comfrey internally as a tea or tincture. However, the healing of bones is a long process, generally longer than is recommended to use comfrey internally. Fortunately, comfrey can also be used in a homeopathic potency for this purpose, which is completely safe. I recommend taking comfrey tea or tincture three to four 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 and switch to the 30C potency of Symphytum taken three to four times per day until the fracture is completely healed. Never begin to use comfrey in any form until the fracture has been set. It will not be possible to use the herb topically when a cast is required. Nevertheless, it will still be beneficial to use an external preparation for about a week after the cast is removed.

Comfrey is one of the most soothing and healing herbs for the mucus membranes of the 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.


Now that I’ve covered the major uses for 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 humans. These generally involved giving isolated pyrrolizidine alkaloids to rats, or occasionally adding comfrey to their diet in very large amounts. However, there have been cases of liver toxicity, sometimes severe, in humans. In these cases the herb was always being used by members of the population who are at high risk for pyrrolizidine alkaloid toxicity or who were using comfrey in excessively large doses for long periods of time. 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 its 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 or species.

2. Comfrey should only be used in combination with other herbs. It should not exceed 20% of formulations for internal use, or 50% of formulations for external use.

3. The use of this herb should be limited to three to four 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 okay to use it if the skin is broken.

4. Comfrey should never be used, internally or externally, by pregnant or nursing women, or infants under the age of one year.

5. It should never 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 not avoid using comfrey altogether and use other herbs instead? The truth is, for the minor conditions for which comfrey is recommended and even for lung conditions most of the time, I do prefer to use other, safer herbs. But for healing irritated, inflamed or damaged tissues, comfrey is unsurpassed and its benefits far outweigh its risks (which are practically non-existent if you observe the precautions indicated above).

Nature has provided us with many medicinal gifts. However, contrary to the belief of some naive idealists, all that is natural is not necessarily safe. It is important that we use these gifts with knowledge, caution and respect. If we do, the healing possibilities are endless. Have a great summer!

Michael Vertolli is a Registered Herbalist practising in Vaughan (just north of Toronto). He is the Director of Living Earth School of Herbalism, which offers in-class and online general interest courses, certificate, and diploma programs. More information: 905-303-8723, ext. 1. Visit: Blog:

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