Products
Preparations from comfrey are commercially available in the form of gels (pain gels) and ointments.
Stem plant
Common comfrey or comfrey, L. (Boraginaceae), is native to Europe. is derived from, “I grow together.” The names comfrey and comfrey are derived from the German verb “wallen,” which means to grow together. Bein originally refers to bones. Thus, the names reflect the traditional use for healing broken bones and injuries. Comfrey was also used as a fertilizer, food, and forage plant.
Medicinal drug
Comfrey ointments are usually made from the freshly harvested root (Symphyti radix rec., Figure 4) and less commonly from the herb (Symphyti herba). As a synonym, Consolidae radix is also commonly used instead of Symphyti radix, as the plant has also been named as.
Ingredients
Comfrey contains allantoin, choline, tannins, mucilages, saponins, rosmarinic acid derivatives and pyrrolizidine alkaloids, among others.
Effects
Comfrey has been attributed with soothing, analgesic, anti-inflammatory, granulation-promoting, wound-healing, antioedematous, and tanning effects. In recent years, a number of clinical studies have been conducted that partially support these effects scientifically (see literature). According to several studies, comfrey ointments are said to be similarly effective as diclofenac gels. We did not assess the quality of the studies.
Indications
Today, comfrey ointments are used mainly for pain and inflammatory conditions resulting from sports injuries (bruises, strains, sprains, contusions, hematomas), rheumatic complaints, arthritis, arthrosis, muscle and joint complaints, tendovaginitis, back pain, for the after-treatment of bone fractures and dislocations, venous complaints, and thrombophlebitis. Traditionally, there are numerous other applications, for example, wound healing promotion. However, the use of comfrey ointments on open wounds is contraindicated according to the expert information.
Dosage
The drugs are applied externally thinly 2-5 times a day and massaged in gently.
Contraindications
Comfrey ointments should not be applied in cases of hypersensitivity, on open wounds, in children (no data), during pregnancy and lactation. Preparations containing comfrey should not be ingested, e.g., as tea, powder, or in the form of capsules, because of the toxic pyrrolizidine alkaloids. An exception are strongly diluted homeopathics, in which these ingredients are no longer detectable. According to the Commission E monograph, comfrey should not be used for more than 4-6 weeks per year. In contrast, no time limit is given in the drug technical information, because the pyrrolizidine alkaloids have been removed in these finished drugs.
Adverse effects
External use appears to be generally well tolerated. Side effects, except for allergic skin reactions, are hardly known. When used internally, severe adverse effects are possible because of the pyrrolizidine alkaloids, which are liver toxic, mutagenic, and carcinogenic. Corresponding case studies are documented in the literature. Preparations containing comfrey should therefore not be taken (for detailed information, see Stickel, Seitz, 2000). When applied externally to intact skin, there appears to be no risk. Some manufacturers use plants low in alkaloids to produce their comfrey ointments and remove the alkaloids during the extraction process. When collecting wild plants, there is some risk of confusion with the poisonous red foxglove because the two plants are somewhat similar.
