Black Root

A genus of 25-35 species of bristly or hairy rhizomatous perennials, ranging through Europe, from the Mediterranean to the Caucasus. Symphytum officinale and S. x. uplandicum are grown as perennial fodder crops, and as a source of high nitrogen mulches, compost material, and fertilizer for organic cultivation. The variegated S. x uplandicum is popular as an ornamental for borders and bog gardens. Symphytum officinale known to the Romans as conferva ("join together") from which the common name "comfrey" is derived. Another common name, "knitbone", also refers to the use of these plants in healing fractures. Comfrey contains allantoin, which promotes cell proliferation and is now synthesized for use in healing creams, and pyrrolizidine alkaloids (in higher quantities in the roots than in the foliage). The alkaloids have been shown to cause liver damage and tumors in laboratory animals. As a result, S. officinale is now banned in the form of tablets and capsules (made from roots and leaves) in several countries. Comfrey teas, tinctures, and preparations for external use are considered safe. Culpeper wrote the comfrey is "special good for ruptures and bronken bones; yea it is said to be so powerful to consolidate and knit together, that if they be boiled with dissevered pieces of flesh in a pot, it will join them together again" (The English Physician Enlarged, 1653). He also used it for hemorrhoids and sore breasts, for which synthetic allantoin is now specifically used in pharmaceutical products.

Applied in cream form or as a poultice, comfrey, also known as bruisewort, has long been used to heal bruises and other tissue damage, as it contains allantoin, a substance that stimulates the growth of new cells. However, it also contains pyrrolizidine alkaloids that, when ingested over a period of time, may cause liver cancer, so internal use is not recommended.

Stout, bristly-haired perennial with mucilaginous, thick roots, and large, tapering, ovate-lanceolate leaves, 25cm (10in) long. Purple to pink or white, funnel-shaped flowers, to 2cm (¾in) long, are borne in summer.

Common Name:
Black Root
Other Names:
Bruisewort, Comfrey, Knitbone, Slippery Root, Wallwort
Botanical Name:
Symphytum officinale
Native Location:
Europe and W Asia
Moist to wet soil in sun or partial shade. Comfrey is invasive and deep-rooted, and difficult to erradicate when established. Plants may be affected by rust.
By seed sown in autumn or spring (species only); by division in spring or autumn.
Leaves are picked in early summer before flowering and dried for infusions, liquid extracts, and poultices. Roots are lifted during dormancy and dried for decoctions, liquid extracts, and ointments.
60cm-1.2m (2-4ft)
30-60cm (12-24in)
Parts Used:
Leaves, roots
A sweet, mucilaginous, cooling herb with expectorant, astringent, soothing, and healing effects. It reduces inflammation, and controls bleeding.
Medicinal Uses:
Internally for gastric and duodenal ulcers, chronic bronchial diseases, colitis, irritable bowel syndrome, and rheumatism (leaves). Externally for psoriasis, eczema, sores, varicose veins and ulcers, arthritis, sprains, bunions, hemorrhoids, sore breasts during lactation, and injuries, including fractures.
To treat gum disease, strep throat, inflammation of the throat, stomach ulcers, bruises, sprains, and pulled ligaments and muscles; to promote bone healing. Germany's Commission E has approved the use of comfrey to treat blunt injuries.
Typical Dose:
Internal use is no longer recommended because of the potential for liver damage. For external use, topical products containing comfrey (5 to 20 percent of dried herb present in product) may be used as needed, but not for longer than four weeks and only on unbroken skin.
Possible Side Effects:
Comfrey's side effects include allergic reactions (from oral or topical use) and nausea, vomiting, abdominal pain, liver damage, and liver cancer (from oral use).
Drug Interactions:
Taking comfrey internally with these drugs may cause or increase liver damage:
Abacavir, (Ziagen)
Acarbose, (Prandase, Precose)
Acetaminophen, (Genepap, Tylenol)
Allopurinol, (Aloprim, Zyloprim)
Atorvastatin, (Lipitor)
Celecoxib, (Celebrex)
Cidofovir, (Vistide)
Cyclosporine, (Neoral, Sandimmune)
Docetaxel, (Taxotere)
Dofetilide, (Tikosyn)
Erythromycin, (Erythrocin, Staticin)
Etodolac, (Lodine, Utradol)
Fluconazole, (Apo-Fluconazole, Diflucan)
Fluphenazine, (Modecate, Prolixin)
Fluvastatin, (Lescol)
Foscarnet, (Foscavir)
Ganciclovir, (Cytovene, Vitrasert)
Gemfibrozil, (Apo-Gemfibrozil, Lopid)
Gentamicin, (Alcomicin, Gentacidin)
Ibuprofen, (Advil, Motrin)
Indinavir, (Crixivan)
Isoniazid, (Isotamiune, Nydrazid)
Ketoconazole, (Apo-Ketoconazole, Nizoral)
Ketoprofen, (Orudis, Rhodis)
Ketorolac, (Acular, Toradol)
Lamivudine, (Epivir, Heptovir)
Levodopa-Carbidopa, (Nu-Levocarb, Sinemet)
Lovastatin, (Altocor, Mevacor)
Meloxicam, (MOBIC, Mobicox)
Methotrexate, (Rheumatrex, Trexall)
Methyldopa, (Apo-Methyldopa, Nu-Medopa)
Morphine Hydrochloride, (Morphine Hydrochloride)
Morphine Sulfate, (Kadian, MS Contin)
Naproxen, (Aleve, Naprosyn)
Nelfinavir, (Viracept)
Nevirapine, (Viramune)
Nitrofurantoin, (Macrobid, Furadantin)
Ondansetron, (Zofran)
Paclitaxel, (Onxol, Taxol)
Pantoprazole, (Pantoloc, Protonix)
Phenytoin, (Dilantin, Phenytek)
Pioglitazone, (Actos)
Piroxicam, (Feldene, Nu-Pirox)
Pravastatin, (Novo-Pravastatin, Pravachol)
Prochlorperazine, (Compazine, Compro)
Propoxyphene, (Darvon, Darvon-N)
Repaglinide, (GlucoNorm, Prandin)
Rifampin, (Rifadin, Rimactane)
Rifapentine, (Priftin)
Ritonavir, (Norvir)
Rofecoxib, (Vioxx)
Rosiglitazone, (Avandia)
Saquinavir, (Fortovase, Invirase)
Simvastatin, (Apo-Simvastatin, Zocor)
Stavudine, (Zerit)
Tamoxifen, (Nolvadex, Tamofen)
Tramadol, (Ultram)
Zidovudine, (Novo-AZT, Retrovir)
Lab Test Alterations:
May increase values on liver function tests, including aspartic acid transaminase (AST), alanine aminotransferase (ALT), total bilirubin, and urine bilirubin.
Disease Effects:
May worse liver disease.
Supplement Interactions:
  • May increase the risk of liver damage when combined with herbs and supplements that can cause hepatotoxicity (destructive effects on the liver), such as Bishop's Weed, Borage, Chaparral, Uva Ursi, and others.
  • Enhanced toxicity when taken with herbs and supplements that induce Cytochrome P450 3A4, such as Garlic and St. John's Wort.
  • Increased risk of additive toxicity when used with herbs and supplements containing unsaturated pyrrolizidine alkaloids (UPAs), such as Butterbur and Colt's Foot.
Bristly foliage is a skin irritant.
This herb, especially in the form of tablets and capsules of the roots or leaves, is subject to legal restrictions in some countries.
Culinary Uses:
Fresh young leaves are added to salads, made into fritters, or cooked as a vegetable in similar ways to spinach. Dried leaves are used to make tea.
Encyclopedia of herbs by Deni Brown Copyright © 1995, 2001 Dorling Kindersley Limited. pg 377
The Essential Herb-Drug-Vitamin Interaction Guide by Geo. T. Grossberg,MD and Barry Fox,PhD Copyright©2007 Barry Fox,PhD. Pp.162-163