Using comfrey externally to heal bruises, sprains, and other injuries, information on alkaloid toxicity, and how to make comfrey oil
Comfrey is a controversial plant. Many gardeners have it growing somewhere whether it’s a relic of a past garden or used to make plant feed. Bees and other pollinators love it too and for that reason alone it’s a fabulous plant to have in an organic garden. I have several clumps in my allotment and use the leaves as a compost activator, a feed, and also in ointments. The reason I use it? In one study it’s been shown to accelerate skin healing by 58%.
Although I’m sharing how to make comfrey oil it’s important to understand the discussion around it. Namely, the danger of pyrrolizidine alkaloids, and the safest ways to use comfrey. Just like other medicinal plants, comfrey should be understood and respected before using it.
Skin-healing comfrey oil
Comfrey is a powerful wound healer thanks to its allantoin, saponins, polysacharides, and other natural plant chemicals. On par with calendula on that front, it has the ability to treat bruises, sprains, pulled muscles, and other tissue damage.
It’s so powerful that it should not be used directly on open wounds. It can stimulate healing on the outside and trap microbes inside. You don’t want bacteria and other microorganisms inside wounds since they can cause abscesses. There’s another reason that it shouldn’t be used on wounds that we’ll come to shortly.
It’s the leaves that you want to use to make medicinal salves. Once dried, it’s easy to use them to make comfrey oil. You use comfrey oil direct on the skin or mixed with other ingredients to make this Healing Salve. Please note that comfrey is a powerful medicinal herb and should not be used in daily skin care. It’s one for those special circumstances when your skin needs some deep therapy and healing.
Although comfrey is a wonderful skin healer, it also has a long history of use for internal injuries. Traditional folk medicine has it used in all kinds of preparations, from poultices to lay on the skin to medicinal teas. Incredibly, it’s been used for at over 2000 years. However, studies using rats have shown that it can be dangerous when taken internally.
There is A LOT of information on comfrey and potential toxicity out there. Quite a lot of folks that defend its safely too. The bottom line is that all varieties of comfrey contains alkaloids that could cause liver damage. Especially when taken internally, in high doses, and/or long periods. This is why you should avoid using comfrey root at all, since it has ten times more pyrrolizidine alkaloids than the leaves.
Fortunately, these alkaloids are not easily absorbed by the skin. That makes using comfrey oil on your skin safe, as long as it’s not put on open wounds or sores.
Using homegrown to make comfrey oil
Although you can purchase dried comfrey leaves from many cosmetic and herbal suppliers it’s easy to grow. The most common variety these days is a cultivar called Symphytum x uplandicum. You’ll also find it called Russian comfrey or Bocking 14. There’s some discussion on whether or not it contains higher levels of alkaloids than others. However, it’s the one that I grow and use. It’s also the same variety used in the study on wound healing.
Common Comfrey (Symphytum officinale) may be lower in alkaloids so could be safer to use in herbal preparations. It also contains little or no Echimidine, the most toxic of the eight alkaloids present in comfrey.
Drying comfrey leaves
Older leaves, or leaves that have overwintered in mild climates, may have higher concentrations of alkaloids. Pick only relatively young, fresh leaves before any flowers are showing on the plant. Dry them by stringing them up on thread like bunting, or in a food dehydrator. They should be dry and crumbly before you use them to make comfrey oil. Leaves that are fresh or wet can introduce water into the oil which accelerates rancidity. It can create habitat for microbes, whether you see them or not.
I recently tried air-drying comfrey in bunches as an experiment. This isn’t usually recommended since the stems are so fleshy and take a while to dry. In my case it worked fine but did take an extra couple of days. If you try it yourself, make sure that the bundles aren’t too tightly strung together to allow for air flow.
Using comfrey oil
You can use whole comfrey leaves as a poultice for sprains, arthritis, pain, and bruising. If you don’t want to walk around with a bandage of leaves sticking to you then you can make comfrey oil. Rub it onto the same injuries like a massage oil but avoid putting it on broken skin or wounds. You can also use the oil to make a salve that will rub in and stay on a lot better.
The dosing advice from WebMD is to use comfrey oil (extract) three times daily for up to three weeks depending on complaint. Comfrey should not be used on children or if you are pregnant or nursing.
How to make Comfrey Oil
- Clean, sterilized jar
- Metal sieve
- Although you can sometimes purchase herb-infused oils, they're actually very easy to make yourself. This is a folk-method of making comfrey-infused oil and its strength will vary depending on a number of factors. The time of year it is, when the plant material was picked, at what life-stage the leaves and plant are, how the leaves were dried, and how old the herbs and oil are.
- If you grow or can forage comfrey yourself, pick the leaves when they're at their best on a bright, dry morning. Leaves should be young and lush and it's best to pick them before the plant flowers.
- Dry the comfrey leaves completely. The stems are fleshy and wet so begin by pulling the leaves off and drying on a screen or in a food dehydrator. Alternatively, you can use needle and thread to string the leaves up like medicinal bunting. Air drying takes up to a week.
- Fill the jar 2/3 full with dried* comfrey leaves. Tear or shred them to increase the surface area.
- Fill the rest of the jar with a liquid oil of your choice such as sweet almond oil**.
- Wait a minute or so and top up the jars with more oil if the level goes down. Also make sure that the herbs are completely submerged.
- Place the jar(s) in a warm place for 3-6 weeks. The general advice is to give them a little shake every day. I tend to shake them when I remember to do it. You should pop the jars in brown paper bags if you decide to put them on a window sill***.
- After the 3-6 weeks have passed, strain the leaves out of the oil by pouring it all out into a cheese cloth lined sieve/strainer. Capture the oil in a bowl below and make sure to wring as much oil out of the cheese cloth as possible. In most cases, the infused-oil color is different from the original. In the case of comfrey oil, it's far more golden.
- Discard the herbs and bottle the infused oil up. You can use the same jar used for infusing or specialist dark jars that herbalists use****. Either way, make sure to store the oil someplace cook and out of direct sunlight.
- The oil has a shelf-life of one year or the best-by date of the original bottle of oil you used. Whichever is closer.
Wound healing effects of a Symphytum herb extract cream (Symphytum x uplandicum NYMAN: ): results of a randomized, controlled double-blind study. From linear regression time to complete healing was determined to be 2.97 days faster with verum than with the reference (4.08 vs. 7.05 days). Barna M, Kucera A, Hladícova M, Kucera M, Wien Med Wochenschr. 2007; 157(21-22):569-74.
 WebMD Comfrey
 Comfrey. T.M. Teynor, D.H. Putnam, J.D. Doll3, K.A. Kelling, E.A. Oelke, D.J. Undersander, and E.S. Oplinger
Metabolism, genotoxicity, and carcinogenicity of Comfrey. Nan Mei, Lei Guo, Peter P. Fu, James C. Fuscoe, Yang Luan, and Tao Chen. J Toxicol Environ Health B Crit Rev. 2010 Oct; 13(7-8): 509–526.
 COMFREY (Symphytum officinale): A healer of wounds, bruises and bones, Cambridge Naturals, Steph Zabel Herbalist, Ethnobotanist
 Comfrey and Pyrriolizidine Alkaloids Research. Nantahala Farm.
Penetration of lycopsamine from a comfrey ointment through human epidermis. Regul Toxicol Pharmacol. 2017 Feb;83:1-4. doi: 10.1016/j.yrtph.2016.11.015. Epub 2016 Nov 11. Jedlinszki N, Balázs B, Csányi E, Csupor D.
 Gale Encyclopedia of Alternative Medicine, 2005, 2nd edition. Quote from Varro Tyler of the Purdue University School of Pharmacy
 Comfrey dosing from WebMD