Comfrey

Symphytum officinale

Snapshot

Indications	Contraindications
Ankle sprain pain and swelling^1–4 Knee osteoarthritis pain^5–7 Low back pain^{8, 9} Abrasion healing^{10, 11} Injection-site bruising¹²	Oral use¹³ Broken or irritated skin¹⁴ Hypersensitivity to comfrey¹⁴ Pregnancy and lactation¹⁵

Comfrey (Symphytum officinale) leaf and root have been used for centuries for wound healing and inflammation¹⁶. Allantoin and rosmarinic acid are proposed to drive its tissue-proliferating and anti-inflammatory effects¹⁶. Adults use topical root extract for ankle sprains, knee osteoarthritis, and low back pain. Leaf-herb cream is used for abrasions and injection-site bruising^10–12.

In acute ankle sprain, a root extract ointment outperformed placebo¹ and was non-inferior to diclofenac gel². A Cochrane review judged comfrey extract gel likely to improve knee osteoarthritis pain⁵, while evidence in low back pain was low quality. In rats, a 2026 study found comfrey leaf and flower extracts shortened bleeding time and sped wound closure; no human trial has tested them. Twenty-nine products listing comfrey are mostly liquids, with some capsules, powders, and tablets; see Form comparison.

The most consequential caution is oral use: pyrrolizidine alkaloids are converted to toxic metabolites, and LiverTox rates oral comfrey a probable cause of sinusoidal obstruction syndrome, a form of liver injury¹³. The European traditional-use monograph limits comfrey to unbroken skin and short courses, and directs patients to a doctor or qualified health care practitioner if symptoms persist¹⁴.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

41 sources, 33 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources