Plant Comparison
Willow Bark vs Common Comfrey
A side-by-side comparison of two medicinal plants — every documented constituent, action, use, safety note and cited source, assembled automatically from the Omnia Sana database.
At a glance
Willow Bark and Common Comfrey: they share 6 indicated uses (arthritis / joint pain, back pain, headache, …); 2 pharmacological actions in common.
Evidence face-off — shared uses
| Condition | Willow Bark | Common Comfrey | Verdict |
|---|---|---|---|
| Arthritis / joint pain | 7/10 | 5/10 | Stronger for Willow Bark |
| Back pain | 9/10 | 5/10 | Stronger for Willow Bark |
| Headache | 1/10 | 5/10 | Stronger for Common Comfrey |
| Inflammation (general) | 8/10 | 5/10 | Stronger for Willow Bark |
| Pain (general) | 9/10 | 8/10 | Comparable evidence |
| Skin irritation | 8/10 | 5/10 | Stronger for Willow Bark |
Evidence scores (1–10) are computed from the tier of each cited source. “Comparable” means the two scores are within one point. Follow a score to its detailed sources.
Key Constituents
Metabolised in the body to salicylic acid - the 'natural aspirin' that gives the analgesic, anti-inflammatory and antipyretic effects.
The key cell-proliferative constituent underlying comfrey's wound-healing reputation.
Contribute to the soothing, demulcent texture of the leaf and root.
Contribute to antioxidant and anti-inflammatory activity.
Hepatotoxic constituents naturally present in the whole plant; the reason internal use is not recommended and processed/detoxified extracts are used for research.
Pharmacological Actions
Analgesic and anti-inflammatory for low back pain (moderate evidence; dose-dependent, around 240 mg salicin/day) - in an RCT, 240 mg salicin/day left 39% pain-free vs 6% on placebo within 4 weeks
Analgesic and anti-inflammatory for low back pain (moderate evidence; dose-dependent, around 240 mg salicin/day) - in an RCT, 240 mg salicin/day left 39% pain-free vs 6% on placebo within 4 weeks
Antipyretic (reduces fever)
Traditional & Indicated Uses
Relief of joint pain, osteoarthritis and rheumatic complaints
Analgesic and anti-inflammatory for low back pain (moderate evidence; dose-dependent, around 240 mg salicin/day) - in an RCT, 240 mg salicin/day left 39% pain-free vs 6% on placebo within 4 weeks
inferred from anti-inflammatory action
Analgesic and anti-inflammatory for low back pain (moderate evidence; dose-dependent, around 240 mg salicin/day) - in an RCT, 240 mg salicin/day left 39% pain-free vs 6% on placebo within 4 weeks; Relief of joint pain, osteoarthritis and rheumatic complaints
inferred from anti-inflammatory action
inferred from anti-inflammatory action
inferred from anti-inflammatory action
inferred from anti-oedematous action
Safety, Cautions & Contraindications
Because it works like aspirin, avoid willow bark if you are allergic to aspirin or salicylates, and do NOT give it to children or teenagers with a viral illness (risk of Reye's syndrome). Use caution in asthma (salicylate sensitivity).
Avoid with anticoagulant/antiplatelet medicines (bleeding risk) and in active peptic ulcer; avoid in pregnancy (especially the third trimester) and breastfeeding.
Big headline: Comfrey naturally contains pyrrolizidine alkaloids (PAs), which can seriously harm the liver if taken internally (Staiger, 2012; EMA, 2015). • Do not ingest comfrey (no teas, no internal tinctures, no capsules), because PA exposure from internal use is the main safety problem (Staiger, 2012; Bach et al., 1990). • Topical use only, short-term: EU herbal guidance describes comfrey root preparations for minor bruises and sprains in adults, and recommends limited duration (commonly up to about 10 days) (EMA, 2015; EMA/HMPC, 2024). • Do not apply to broken skin (open wounds, damaged/irritated skin) and avoid eyes/mucous membranes (EMA/HMPC, 2024). • Pregnancy & breastfeeding: best avoided (not enough safety margin for medicinal use) (EMA/HMPC, 2024). • Children/adolescents: not recommended for medicinal topical use in EU monograph context (EMA/HMPC, 2024). • If you have liver disease or take medicines that stress the liver, skip comfrey completely (risk management logic based on PA concern) (Staiger, 2012; EMA, 2015). • Skin reactions: mild rash/irritation can occur; stop if it irritates (Smith and Jacobson, 2011).
Duke (2002) classifies common comfrey (Symphytum officinale) with anti-inflammatory and wound-healing properties, supported by allantoin content (promotes cell proliferation). However, comfrey also contains hepatotoxic pyrrolizidine alkaloids. Internal use is no longer recommended, and Commission E approved only external use. Duke emphasizes that pyrrolizidine alkaloids are cumulative hepatotoxins associated with veno-occlusive disease, and prolonged or internal use is contraindicated (Duke, 2002).
External Ids
Botanical Description
Large deciduous tree (Salicaceae), 10-25 m tall (occasionally taller), fast-growing with a broad crown. Leaves are narrow and lance-shaped, silvery-white and silky-hairy beneath, giving the tree a shimmering appearance in the wind. Tiny flowers are borne in catkins appearing with the leaves in spring; the species is dioecious. The fruit is a small capsule releasing cottony-tufted seeds.[12]
Robust, hairy perennial herb (Boraginaceae), 60-120 cm tall, with a thick, black-skinned, mucilaginous taproot. Leaves are large, broad, lance-shaped and bristly-hairy, running down the stem as raised wings (decurrent) - the leaf base's smooth, untoothed margin is a key feature distinguishing it from toxic foxglove. Drooping clusters of tubular, bell-shaped flowers are cream, pink or purple depending on variety.[11]
Habitat
Native to Europe, western and central Asia and North Africa, growing on damp ground along riverbanks, floodplains and wet meadows; widely planted and naturalised elsewhere.[12]
Native to Europe and western Asia, growing in damp ground - riverbanks, ditches, damp meadows and waste ground - and widely cultivated.[11]
Harvesting
Bark is stripped from young branches (2-3-year-old growth is preferred, as salicin content is highest in younger bark) in spring, when the rising sap makes the bark peel most easily, then dried.[12]
Leaves are cut during the growing season (before flowering is often preferred for lower pyrrolizidine-alkaloid content); root is dug in autumn or spring from mature plants.[11]
Traditional Uses
Willow bark has one of the longest documented histories of any medicinal plant, used since antiquity (recorded by Hippocrates) as a remedy for pain and fever. Its salicin content, chemically related to aspirin, gives it official European herbal-monograph recognition for mild joint pain, headache and feverish colds, with modern clinical trials supporting benefit for low back pain.[11, 12]
Comfrey has one of the strongest traditional reputations of any European herb for wound healing and bone/tissue repair - the folk names 'knitbone' and 'boneset' reflect this - owing to its high allantoin content, which stimulates cell proliferation. Because the plant also contains hepatotoxic pyrrolizidine alkaloids, modern regulatory use is restricted to topical preparations only, for minor bruises and sprains, and internal use (teas, tinctures) is no longer recommended.[11]
Preparations
The officially recognised European herbal-monograph preparation, for minor bruises and sprains, short-term use only.
Dosage
Clinical trials for back pain have used around 240 mg salicin/day of standardised extract. Educational reference only, not a prescription; avoid if allergic to aspirin/salicylates, in children/teenagers with a viral illness (Reye's syndrome risk), or alongside anticoagulants.
EU herbal-monograph guidance describes comfrey root preparations applied topically for minor bruises and sprains in adults, for a limited duration (commonly up to about 10 days); do not apply to broken skin or near eyes/mucous membranes. Comfrey must never be taken internally (no teas, tinctures or capsules) because of its pyrrolizidine alkaloid content. Educational reference only, not a prescription.
References
Lookalikes Review
Dangerous Lookalikes
Not documented
References & Sources
- Shara, M. and Stohs, S.J (2015) 'Efficacy and Safety of White Willow Bark (Salix alba) Extracts', Phytotherapy Research, 29(8), pp. 1112-1116. doi:10.1002/ptr.5377 Meta-analysis / review
https://doi.org/10.1002/ptr.5377 - Maistro, E.L., Terrazzas, P.M., Perazzo, F.F., Gaivao, I.O.M. and others (2020) 'Salix alba (white willow) medicinal plant presents genotoxic effects in human cultured leukocytes', Journal of Toxicology and Environmental Health, Part A, 82(23-24), pp. 1223-1234. doi:10.1080/15287394.2019.1711476 Preclinical
https://doi.org/10.1080/15287394.2019.1711476 - Matyjaszczyk, E. and Schumann, R. (EU-FORA) (2018) 'Risk assessment of white willow (Salix alba) in food', EFSA Journal, 16(Suppl 1), pp. e16081. doi:10.2903/j.efsa.2018.e16081 Meta-analysis / review
https://doi.org/10.2903/j.efsa.2018.e16081 - Phillips, H.N., Sharpe, K.T., Endres, M.I. and Heins, B.J (2021) 'Effects of oral white willow bark (Salix alba) and intravenous flunixin meglumine on prostaglandin E2 in healthy dairy calves', JDS Communications, 3(1), pp. 49-54. doi:10.3168/jdsc.2021-0138 Preclinical
https://doi.org/10.3168/jdsc.2021-0138 - Kong, C.S., Kim, K.H., Choi, J.S., Kim, J.E. and others (2014) 'Salicin, an extract from white willow bark, inhibits angiogenesis by blocking the ROS-ERK pathways', Phytotherapy Research, 28(8), pp. 1246-1251. doi:10.1002/ptr.5126 Preclinical
https://doi.org/10.1002/ptr.5126 - Noleto-Dias, C., Ward, J.L., Bellisai, A., Lomax, C. and Beale, M.H (2018) 'Salicin-7-sulfate: A new salicinoid from willow and implications for herbal medicine', Fitoterapia, 127, pp. 166-172. doi:10.1016/j.fitote.2018.02.009 Preclinical
https://doi.org/10.1016/j.fitote.2018.02.009 - Wolfle, U., Haarhaus, B., Kersten, A., Fiebich, B. and others (2015) 'Salicin from Willow Bark can Modulate Neurite Outgrowth in Human Neuroblastoma SH-SY5Y Cells', Phytotherapy Research, 29(10), pp. 1494-1500. doi:10.1002/ptr.5400 Preclinical
https://doi.org/10.1002/ptr.5400 - Gagnier, J.J., van Tulder, M., Berman, B. and Bombardier, C (2006) 'Herbal medicine for low back pain (Cochrane review)', Cochrane Database of Systematic Reviews, (2), pp. CD004504. doi:10.1002/14651858.CD004504.pub3 Meta-analysis / review
https://doi.org/10.1002/14651858.CD004504.pub3 - Oltean, H., Robbins, C., van Tulder, M.W., Berman, B.M. and others (2014) 'Herbal medicine for low-back pain (Cochrane review update)', Cochrane Database of Systematic Reviews, 2014(12), pp. CD004504. doi:10.1002/14651858.CD004504.pub4 Meta-analysis / review
https://doi.org/10.1002/14651858.CD004504.pub4 - Amel Zabihi, N., Mahmoudabady, M., Soukhtanloo, M., Hayatdavoudi, P. and others (2018) 'Salix alba attenuated oxidative stress in the heart and kidney of hypercholesterolemic rabbits', Avicenna Journal of Phytomedicine, 8(1), pp. 63-72. Preclinical
https://scholar.google.com/scholar?q=Salix%20alba%20attenuated%20oxidative%20stress%20in%20the%20heart%20and%20kidney%20of%20hypercholesterolemic%20rabbits - Vlachojannis, J.E., Cameron, M. and Chrubasik, S (2009) 'A systematic review on the effectiveness of willow bark for musculoskeletal pain', Phytotherapy Research. doi:10.1002/ptr.2747 Meta-analysis / review
https://doi.org/10.1002/ptr.2747 - European Medicines Agency (HMPC) (n.d.) 'European Union herbal monograph on Salix [various species], cortex (Salicis cortex)'. Available at: https://www.ema.europa.eu/en/medicines/herbal/salicis-cortex Traditional / reference
https://www.ema.europa.eu/en/medicines/herbal/salicis-cortex - Chrubasik, S., Eisenberg, E., Balan, E., Weinberger, T., Luzzati, R. and Conradt, C (2000) 'Treatment of low back pain exacerbations with willow bark extract: a randomized double-blind study', The American Journal of Medicine, 109(1), pp. 9--14. doi:10.1016/S0002-9343(00)00442-3 Randomized trial
https://doi.org/10.1016/S0002-9343(00)00442-3
- Syarifah, A.N., Suryadi, H., Hayun, H., Simamora, A. and others (2023) 'Detoxification of comfrey (Symphytum officinale L.) extract using natural deep eutectic solvent (NADES) and evaluation of its anti-inflammatory, antioxidant, and hepatoprotective properties', Frontiers in Pharmacology, 14, pp. 1012716. doi:10.3389/fphar.2023.1012716 Preclinical
https://doi.org/10.3389/fphar.2023.1012716 - Melnyk, N., Popowski, D., Strawa, J.W., Przygodzinska, K. and others (2023) 'Skin microbiota metabolism of natural products from comfrey root (Symphytum officinale L.)', Journal of Ethnopharmacology, 318(Pt B), pp. 116968. doi:10.1016/j.jep.2023.116968 Preclinical
https://doi.org/10.1016/j.jep.2023.116968 - Trifan, A., Skalicka-Wozniak, K., Granica, S., Czerwinska, M.E. and others (2020) 'Symphytum officinale L.: Liquid-liquid chromatography isolation of caffeic acid oligomers and evaluation of their influence on pro-inflammatory cytokine release in LPS-stimulated neutrophils', Journal of Ethnopharmacology, 262, pp. 113169. doi:10.1016/j.jep.2020.113169 Preclinical
https://doi.org/10.1016/j.jep.2020.113169 - Brown, A.W., Stegelmeier, B.L., Colegate, S.M., Gardner, D.R. and others (2016) 'The comparative toxicity of a reduced, crude comfrey (Symphytum officinale) alkaloid extract and the pure, comfrey-derived pyrrolizidine alkaloids, lycopsamine and intermedine in chicks (Gallus gallus domesticus)', Journal of Applied Toxicology, 36(5), pp. 716-725. doi:10.1002/jat.3205 Preclinical
https://doi.org/10.1002/jat.3205 - Trifan, A., Wolfram, E., Esslinger, N., Grubelnik, A. and others (2021) 'Globoidnan A, rabdosiin and globoidnan B as new phenolic markers in European-sourced comfrey (Symphytum officinale L.) root samples', Phytochemical Analysis, 32(4), pp. 482-494. doi:10.1002/pca.2996 Preclinical
https://doi.org/10.1002/pca.2996 - Nastic, N., Borras-Linares, I., Lozano-Sanchez, J., Svarc-Gajic, J. and others (2020) 'Comparative Assessment of Phytochemical Profiles of Comfrey (Symphytum officinale L.) Root Extracts Obtained by Different Extraction Techniques', Molecules, 25(4), pp. 837. doi:10.3390/molecules25040837 Preclinical
https://doi.org/10.3390/molecules25040837 - Frost, R., MacPherson, H. and O'Meara, S (2013) 'A critical scoping review of external uses of comfrey (Symphytum spp.)', Complementary Therapies in Medicine, 21(6), pp. 724-745. doi:10.1016/j.ctim.2013.09.009 Meta-analysis / review
https://doi.org/10.1016/j.ctim.2013.09.009 - Trifan, A., Opitz, S.E.W., Josuran, R., Grubelnik, A. and others (2018) 'Is comfrey root more than toxic pyrrolizidine alkaloids? Salvianolic acids among antioxidant polyphenols in comfrey (Symphytum officinale L.) roots', Food and Chemical Toxicology, 112, pp. 178-187. doi:10.1016/j.fct.2017.12.051 Preclinical
https://doi.org/10.1016/j.fct.2017.12.051 - Dey, D., Jingar, P., Agrawal, S., Shrivastava, V. and others (2019) 'Symphytum officinale augments osteogenesis in human bone marrow-derived mesenchymal stem cells in vitro as they differentiate into osteoblasts', Journal of Ethnopharmacology, 248, pp. 112329. doi:10.1016/j.jep.2019.112329 Preclinical
https://doi.org/10.1016/j.jep.2019.112329 - Kuchta, K. and Schmidt, M (2020) 'Safety of medicinal comfrey cream preparations (Symphytum officinale s.l.): The pyrrolizidine alkaloid lycopsamine is poorly absorbed through human skin', Regulatory Toxicology and Pharmacology, 118, pp. 104784. doi:10.1016/j.yrtph.2020.104784 Preclinical
https://doi.org/10.1016/j.yrtph.2020.104784 - European Medicines Agency (2011) 'European Union herbal monograph on Symphytum officinale L., radix'. Traditional / reference
https://scholar.google.com/scholar?q=European%20Union%20herbal%20monograph%20on%20Symphytum%20officinale%20L.%2C%20radix - Royal Botanic Gardens, Kew (n.d.). Available at: https://powo.science.kew.org Traditional / reference
https://powo.science.kew.org - Staiger, C (2012) 'Comfrey: a clinical overview', 26(10), pp. 1441--1448. doi:10.1002/ptr.4612 Randomized trial
https://doi.org/10.1002/ptr.4612 - Duke, J.A (2002) 'Handbook of Medicinal Herbs, Second Edition'. Traditional / reference
https://scholar.google.com/scholar?q=Handbook%20of%20Medicinal%20Herbs%2C%20Second%20Edition - Vithayathil, M.K. and Edwards, M (2016) 'Comfrey herbal remedy causing second-degree heart block: do not be outfoxed by digitalis', BMJ Case Reports, 2016, pp. bcr2016216995. doi:10.1136/bcr-2016-216995 Clinical study
https://doi.org/10.1136/bcr-2016-216995 - Lin, C.C. and Yang, C.C. and Phua, D.H. and Deng, J.F. and Lu, L.H (2010) 'An outbreak of foxglove leaf poisoning', Journal of the Chinese Medical Association, 73(2), pp. 97-100. doi:10.1016/S1726-4901(10)70009-5 Clinical study
https://doi.org/10.1016/S1726-4901(10)70009-5 - Woodland Trust (2024) 'Foxglove (Digitalis purpurea)'. Available at: https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/plants/wild-flowers/foxglove/ Traditional / reference
https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/plants/wild-flowers/foxglove/
Generated automatically from the Omnia Sana plant database and its cited sources. For educational purposes only — not medical advice. Always consult a qualified practitioner before using medicinal plants.