Comfrey
Important Disclaimer
This is not medical advice. Consult a qualified healthcare provider before using any remedy, especially if pregnant, breastfeeding, on medication, or managing a health condition.
Overview
Comfrey is a robust perennial herb with large hairy leaves and clusters of purple or white bell-shaped flowers. Historically called "knitbone," it has been used for over 2,000 years to accelerate healing of fractures, sprains, and wounds. Its remarkable healing properties come from allantoin, a compound that stimulates cell proliferation. IMPORTANT: Comfrey contains pyrrolizidine alkaloids (PAs) that are toxic to the liver when taken internally. Modern use is restricted to topical application only.
Traditional Use
Comfrey has been used in European herbal medicine since at least 400 BC. Ancient Greek physician Dioscorides recommended it for healing broken bones and wounds. Medieval herbalists called it "knitbone" and used it extensively for fractures, sprains, and bruises. Poultices of comfrey root were applied to broken bones to speed healing. It was also used internally as a tea for respiratory complaints and ulcers — a practice now considered unsafe due to liver toxicity concerns. By the 20th century, research identified pyrrolizidine alkaloids as the cause of liver damage, leading to restrictions on internal use.
Key Active Compounds
Allantoin
A cell-proliferating compound that stimulates new cell growth, accelerating wound healing, bone repair, and tissue regeneration. This is comfrey's primary healing compound.
Rosmarinic Acid
A potent anti-inflammatory and antioxidant compound that reduces pain and swelling when applied topically.
Pyrrolizidine Alkaloids (PAs)
TOXIC compounds that cause hepatotoxicity (liver damage) and are potentially carcinogenic when taken internally. Present in both root and leaves; root contains higher concentrations.
Mucilage
Soothing polysaccharides that form a protective gel over wounds and irritated tissues, reducing pain and promoting healing.
Evidence-Based Benefits
Accelerates wound and fracture healing
Moderate evidenceMultiple clinical trials confirm that topical comfrey preparations significantly accelerate healing of sprains, fractures, and wounds compared to placebo, primarily through allantoin's cell-proliferating effects.
Reduces pain and inflammation
Moderate evidenceTopical comfrey root extract has been shown in clinical studies to reduce pain and swelling from osteoarthritis, back pain, and sports injuries as effectively as some pharmaceutical topical treatments.
Supports skin regeneration
Some studiesAllantoin and mucilage in comfrey promote skin cell renewal, making it useful for scars, stretch marks, and dry skin conditions when applied topically.
Common Preparation Methods
Topical Poultice (Leaves)
Wash fresh comfrey leaves, bruise or blend them, and apply directly to the affected area. Cover with a clean cloth and leave for 1-2 hours. FOR EXTERNAL USE ONLY.
Dosage: 1-3 times daily, for up to 10 daysDo not apply to open wounds or broken skin. External use only.
Comfrey Salve / Ointment
Use a commercially prepared comfrey salve or cream containing standardized allantoin. Apply to bruises, sprains, or sore muscles 2-3 times daily.
Dosage: Apply 2-3 times dailyLook for products with PA-free certification for safety.
Infused Oil
Infuse dried comfrey root in olive oil for 4-6 weeks. Strain and use as a massage oil for sore muscles and joints.
Dosage: Apply topically as neededFor external use only. Do not use on broken skin.
Safety & Cautions
Please read carefully before use
Contraindications
- NEVER take internally — liver toxicity risk
- Do not apply to open wounds or broken skin (PAs can be absorbed)
- Do not use for more than 10 consecutive days
- Pregnancy and breastfeeding: avoid entirely
- Children under 12: avoid
Drug Interactions
- Internal use may interact with hepatotoxic drugs
- Topical use: no significant drug interactions known
Possible Side Effects
- Topical: rare skin irritation or allergic reaction
- Internal (AVOID): hepatotoxicity, veno-occlusive disease, liver failure, potential carcinogenicity
Special Populations
- Pregnancy: AVOID entirely
- Children: avoid topical use under age 12
- Liver disease: avoid entirely
- Elderly: use with caution; limit duration of topical use
Sources & References
Phytotherapy Research
Food and Chemical Toxicology
Phytomedicine
Quick Reference
Boraginaceae
Root (topical only), Leaves (topical only)
Mucilaginous, slightly bitter — FOR EXTERNAL USE ONLY
Safety First
Always consult with a qualified healthcare provider before starting any new remedy, especially if you have existing health conditions or take medications.