Comfrey

Botanical

What is it

Comfrey (Symphytum officinale and related Symphytum species) is a perennial herb with a long traditional history of use for bruises, sprains, and joint pain. Modern use is overwhelmingly topical because of well-documented internal toxicity.

Evidence for 3 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Acute musculoskeletal pain and ankle sprain (topical)

Good Evidence

Several RCTs of topical comfrey root extract show reductions in pain and improved function for acute sprains and back pain over short courses. Effects are comparable to topical NSAIDs in some trials.

Osteoarthritis pain (topical)

Limited Evidence

Smaller trials show modest symptomatic improvement in knee osteoarthritis. Evidence is supportive but limited.

Any internal/oral use

Mixed Evidence

Oral use is contraindicated due to hepatotoxicity from pyrrolizidine alkaloids. No internal use can be recommended.

How it works

The medicinal effects come from allantoin (which supports cell proliferation and wound healing), rosmarinic acid (anti-inflammatory), tannins, and mucilage. Topically, these compounds reduce inflammation, support tissue repair, and provide local analgesic effects. The problem with comfrey is its pyrrolizidine alkaloids (PAs), which are hepatotoxic and can cause veno-occlusive disease of the liver when absorbed in meaningful amounts. Oral comfrey has been banned or restricted in many countries (including the U.S. by FDA recommendation for internal use) because of this risk. Topical preparations on intact skin produce low systemic PA exposure and are still permitted in many places.

Dosage

No safe oral dose. Topical creams typically deliver standardized comfrey root extract several times daily for up to 4-6 weeks. PA-reduced comfrey products are preferred for topical use.

When and how to take it

Topical creams and ointments are applied 2-4 times daily directly to the affected area. Avoid prolonged continuous use; treatment courses should be limited to 4-6 weeks at a time.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

Topical cream or ointment (PA-reduced)

Safest form for symptomatic musculoskeletal use; choose products that specify low or undetectable PA content.

Minimal systemic absorption through intact skin.

Oral preparations

Contraindicated. Banned for internal use in many jurisdictions.

Pyrrolizidine alkaloids are well absorbed and hepatotoxic.

Safety

Topical use on intact skin for short courses (up to 4-6 weeks) is generally well tolerated. Side effects are mostly local skin reactions. Oral comfrey, prolonged use, application to broken skin, or use of unfractionated whole-herb products carries a real risk of liver injury and is contraindicated. PA-related liver disease can be irreversible and fatal.

Who should be cautious

Do not take comfrey orally. Topical use should be avoided during pregnancy and breastfeeding, on broken skin, on infants, in people with liver disease, and for prolonged courses beyond 4-6 weeks. Choose PA-reduced products when available.

Interactions

Topical use has minimal systemic interactions. Internal use is contraindicated; PAs interact with any hepatotoxic medication (including acetaminophen, methotrexate, statins) and would compound liver injury risk.

Frequently asked questions

Can I drink comfrey tea?⌄

No. Oral comfrey can cause serious, sometimes irreversible liver damage from pyrrolizidine alkaloids and should never be taken internally.

Is topical comfrey safe?⌄

On intact skin, short-term use of PA-reduced comfrey creams is generally considered safe. Do not apply to broken skin or use for prolonged periods.

References

Comfrey on Wikidata — Wikidata link

Comfrey on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Comfrey (PubMed search) — PubMed link

Track Comfrey with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

Coming to App Store
Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.