Boraginaceae · leaf, root

Comfrey

Symphytum officinale

Human clinical trialsExternal use onlyToxicity warning

Root and leaf have topical sprain-trial literature and a hard stop on internal use. Listed so the PA warning is in front, not so anyone shops a tea.

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Safety first

Contains unsaturated pyrrolizidine alkaloids associated with hepatic sinusoidal obstruction and genotoxicity. Internal use is not recommended. External use: short-term, intact skin only — never on broken skin, never in pregnancy. Toxicity warning entry.

This entry exists so you do not use the plant casually. It is not a treatment suggestion.

Tradition vs trials

Traditional record. European vulnerary and bone-knit folklore. Commission E recorded external use; later PA toxicology overran internal tradition.

Trial literature. Short-term topical products have human sprain and back-pain files. Those trials do not license broken-skin or internal use.

Practical ranges

Educational ranges — not a prescription. Culinary use is not an extract.

topical, intact skin
European assessments limit duration (often on the order of 1–2 weeks) and exclude broken skin — not a poultice protocol
EMA HMPC / German Commission E — Educational range only — not a prescription. A licensed clinician individualizes product, dose, and duration.

Pregnancy, nursing, children

Pregnancy. Avoid (internal and external).
Nursing. Avoid.
Children. Avoid.

Contraindications

internal use
broken skin
pregnancy
pre-existing liver disease
long-term external use

Key interactions

hepatotoxic drugs / CYP3A4 inhibitors · avoid
Internal PA plus other liver injury is stacking. Internal use is already out of scope.

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