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Comfrey

Also known as: Symphytum officinale, Symphytum × uplandicum, knitbone, boneset, bruisewort

Evidence under review. — Not yet rated

Topical comfrey cream reliably reduces pain and speeds wound healing — but swallowing it can damage your liver.

  • What it does

    Comfrey is a plant whose root and leaf extracts are used in topical creams and ointments for pain relief and wound healing. Applied to the skin, it has been shown in multiple clinical trials to...

  • Evidence quality

    Evidence base hasn't been formally rated yet. See research below.

  • Clinical dose

    Topical only — internal use not recommended due to toxicity

See full breakdown ↓ Methodology →

What the Science Says

Comfrey is a plant whose root and leaf extracts are used in topical creams and ointments for pain relief and wound healing. Applied to the skin, it has been shown in multiple clinical trials to significantly reduce acute back pain, ankle sprain pain, and knee osteoarthritis pain — in some studies outperforming diclofenac gel. A 10% comfrey herb cream also accelerated wound healing in children with abrasions by nearly a full day compared to a low-dose control. Effects on pain can begin within an hour of application.

What It Doesn't Do

Won't heal cartilage or reduce inflammation markers in osteoarthritis — studies show pain relief without fixing the underlying joint damage. Not safe to take by mouth — internal use causes serious liver damage. Not a substitute for medical care for fractures or severe injuries. No evidence it works as a systemic anti-inflammatory supplement.

Evidence-Based Benefits

Topical comfrey root cream significantly reduces acute upper and lower back pain within 5 days.

Moderate Evidence

Effective at: 35% comfrey root extract cream, 4g applied 3x daily for 5 days

Supporting studies (click to view on PubMed):

PMID 19460762 PMID 22887778

Comfrey extract ointment reduces ankle sprain pain and tenderness as well as or better than diclofenac gel.

Moderate Evidence

Effective at: Comfrey extract ointment applied topically, dose matched to diclofenac gel comparator

Supporting studies (click to view on PubMed):

PMID 18193693

Topical comfrey extract reduces knee pain in osteoarthritis patients over 12 weeks of use.

Moderate Evidence

Effective at: 3.5g/day of standardized comfrey extract cream applied 3x daily for 12 weeks

Supporting studies (click to view on PubMed):

PMID 22863612

A 10% comfrey herb cream speeds abrasion healing in children by nearly one full day versus low-dose control.

Moderate Evidence

Effective at: 10% Symphytum herb extract cream applied topically

Supporting studies (click to view on PubMed):

PMID 22549241

Absorption & Bioavailability

Unknown for topical route — systemic absorption of active compounds through skin appears minimal based on safety data, but toxic pyrrolizidine alkaloids can be absorbed orally and cause liver damage

Red Flags to Watch For

  • Contains pyrrolizidine alkaloids (PAs) — compounds that cause liver damage, are genotoxic, and are potentially carcinogenic when ingested
  • Internal (oral) use is banned or heavily restricted in many countries due to documented hepatotoxicity
  • Topical products can cause skin rash in up to 21% of users — discontinue if rash develops
  • PA content varies widely between plant parts and preparations — roots contain higher concentrations than leaves
  • Not recommended for use on broken skin, during pregnancy, or in children for extended periods
  • Some products marketed as 'natural' may not disclose PA content or may contain unsafe PA levels

Frequently Asked Questions

What does Comfrey do?

Topical comfrey cream reliably reduces pain and speeds wound healing — but swallowing it can damage your liver.

What is the effective dose of Comfrey?

Topical only — internal use not recommended due to toxicity

Is Comfrey safe?

Contains pyrrolizidine alkaloids (PAs) — compounds that cause liver damage, are genotoxic, and are potentially carcinogenic when ingested

What doesn't Comfrey do?

Won't heal cartilage or reduce inflammation markers in osteoarthritis — studies show pain relief without fixing the underlying joint damage.

Research Sources

  • PubMed
  • NIH DSLD

This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-11-08