Comfrey
Symphytum officinale L.Boraginaceae // root · leaf, primarily topical
Overview
Plant parts
root, leaf, primarily topical
Known constituents
allantoin, rosmarinic acid, pyrrolizidine alkaloids
Research corpus coverage
Chemistry notes
- CHEMISTRY: Relevant reported constituents include allantoin; rosmarinic acid; pyrrolizidine alkaloids; constituent presence alone does not establish clinical efficacy.
Uses & Evidence
Traditional / historical use
Documented traditional use — not a claim of established efficacy.
TRADITIONAL: Comfrey has been used for sprains; bruises; wound care; this records historical/traditional use and does not establish efficacy.
MODERATE · regulatory monograph · WHO Monographs on Selected Medicinal Plants
Modern evidence
EVIDENCE: For the major use set (sprains; bruises; wound care), the evidence assessment is limited/mixed: Limited human trials support some topical preparations for pain/contusions; internal use is unsafe.
MODERATE · randomized controlled trial · WHO Monographs on Selected Medicinal Plants
Mixed findings, product heterogeneity, or indirect evidence are preserved in the detailed profile.
Preparation
Forms used traditionally
A listed form does not imply it suits every plant part, or that one preparation is interchangeable with another — see the plant’s own notes below.
PREPARATION: The medicinal material is root; leaf, primarily topical; traditional and modern forms include decoction, tincture, powder/capsule, standardized extract, infusion/tea, extract. No dose or potency is specified.
MODERATE · regulatory monograph · EMA European Union herbal monographs and list entries
Preparation-specific evidence should not be generalized across extracts, teas, oils, or whole herb.
Safety
Additional safety notes (general, unstructured)
Free-text safety notes carried from their source — not broken out by species, route, or hazard type, and not equivalent to the structured records above. Each note names the kind of source it came from.
SAFETY: Major issues include Pyrrolizidine alkaloids can cause severe hepatic veno-occlusive injury; absorption through broken skin is a concern. Contraindications/cautions include Liver disease; internal use; application to broken skin.
MODERATE · observational/case series and expert review · LiverTox: Herbal and Dietary Supplements
SAFETY: Clinically relevant interaction concerns include Additive liver toxicity with hepatotoxic drugs.
MODERATE · observational/case series and expert review · LiverTox: Herbal and Dietary Supplements
Some interactions are theoretical or based on case reports/pharmacokinetics rather than outcome trials.
SAFETY: Pregnancy/lactation reference: Avoid in pregnancy/lactation.
MODERATE · regulatory monograph or evidence synthesis · WHO Monographs on Selected Medicinal Plants
Absence of evidence is not evidence of safety.
Preparation × species risk matrix
Unknown means insufficient evidence was located — not that a form is safe.
Cats
- tinctureCaution
- concentrated extractUnknown
- essential oilUnknown
- glyceriteUnknown
- infused oilUnknown
- salveUnknown
- smoke/combustionUnknown
- tea/infusionUnknown
- whole herbUnknown
Dogs
- tinctureCaution
- concentrated extractUnknown
- essential oilUnknown
- glyceriteUnknown
- infused oilUnknown
- salveUnknown
- smoke/combustionUnknown
- tea/infusionUnknown
- whole herbUnknown
Identity
- Dangerous lookalikeFoxglove
Foxglove leaves have been mistaken for comfrey and brewed as 'comfrey' tea.
Why it matters: Foxglove cardiac glycosides can cause fatal dysrhythmias; a published case was fatal.
HIGH · Fatal cardiac glycoside poisoning due to mistaking foxglove for comfrey
- Synonym
GBIF resolves Symphytum peregrinum Ledeb. as a synonym of Symphytum officinale. The older name still appears in herbal and taxonomic literature.
HIGH · GBIF Species Match API
Botanical synonym
Symphytum peregrinum Ledeb.
Taxonomic identity note
- Comfrey is treated here as Symphytum officinale L. in the family Boraginaceae; recorded older names include Symphytum peregrinum Ledeb..
Sources
Research records are source-linked but may not yet be editorially reviewed.
WHO monograph
NIH LiverTox monograph
- Plants of the World Online1 claim
botanical taxonomy database
EMA monograph
- GBIF Species Match API1 claim
authoritative taxonomic database
peer-reviewed toxicology case report