White willow bark
White willow bark suppliers and sourcing guide
White willow bark is the dried bark of young branches of Salix alba; trade material can also come from related species such as Salix purpurea, Salix daphnoides and Salix x fragilis. The bark is stripped in spring, dried and sold as cut bark, powder, or water or hydroalcoholic extracts. Extracts are commonly standardized to a declared percentage of total salicin by HPLC.
- Category
- Botanicals and mushrooms
- Also known as
- Salix alba · willow bark · Salicis cortex · white willow
- Facts checked
- November 2026
Forms and grades of white willow bark
Suppliers sell different products under the same name. Specify the one you need.
Cut bark
Dried, cut bark for tea and tincture production.
Bark powder
Milled bark, not standardized; salicin content is low and varies by species and lot.
Standardized extract
Dry extract standardized to total salicin (commonly 15% or 25%) by HPLC.
Liquid extract
Tincture or fluid extract sold by bark-to-solvent ratio.
What to check on the COA
Compare each result with your own specification when the lot arrives.
- Identity
- Microscopy or HPTLC fingerprint against a Salix bark reference; the species should be named on the COA.
- Total salicin assay (HPLC)
- Total salicin, often after hydrolysis of salicylic glycosides, by a named HPLC method.
- Residual solvents
- For extracts made with ethanol or other solvents, residual solvent levels against USP <467> or the buyer's spec.
- Heavy metals
- Lead, arsenic, cadmium and mercury, usually by ICP-MS, checked against the buyer's limits and Prop 65 exposure targets where relevant.
- Microbiology
- Total plate count, yeast and mold, E. coli and Salmonella. Raw herb powders carry more microbial load than extracts and may be steam treated, which should be stated on the COA.
- Loss on drying
- Moisture against the spec, plus mesh size and foreign matter for powders.
Storage, lots and expiry
Storage and shelf life
Keep dried herb and powdered extracts sealed in lined drums or bags, away from heat, light and humidity. Dry extracts are hygroscopic and cake once exposed to air, so reseal opened containers promptly. Suppliers assign a shelf life or retest date, and the marker assay is usually repeated at retest before material is used past it.
Lots and expiry dates
Salicin content varies widely between Salix species and harvests, so buy on the lot assay and confirm the species. Record the supplier lot, species, salicin result and retest date.
Regulatory status
Facts from regulators and standards bodies, each linked to its source.
Health Canada's Willow Bark natural health product monograph lists Salix alba, Salix daphnoides, Salix purpurea and Salix x fragilis as source materials, using dried bark or young branch bark.
Source: webprod.hc-sc.gc.ca (opens in a new tab)The same monograph covers standardized extracts providing up to 15% total salicin.
Source: webprod.hc-sc.gc.ca (opens in a new tab)
This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.
White willow bark suppliers
Manufacturers and distributors whose own websites say they sell it.
We are checking white willow bark suppliers now
Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.
Sell white willow bark? Request a listingFrequently asked questions
What forms of white willow bark can brands buy?
Common forms include cut bark, bark powder, standardized extract and liquid extract. Ask each supplier for the specification sheet of the exact grade they quote.
What should the COA for white willow bark include?
Expect identity, total salicin assay (HPLC), residual solvents, heavy metals, microbiology and loss on drying, each with its method, specification and result for that lot.
How should white willow bark be stored?
Keep dried herb and powdered extracts sealed in lined drums or bags, away from heat, light and humidity. Dry extracts are hygroscopic and cake once exposed to air, so reseal opened containers promptly. Suppliers assign a shelf life or retest date, and the marker assay is usually repeated at retest before material is used past it.
What is the regulatory status of white willow bark?
Health Canada's Willow Bark natural health product monograph lists Salix alba, Salix daphnoides, Salix purpurea and Salix x fragilis as source materials, using dried bark or young branch bark. The same monograph covers standardized extracts providing up to 15% total salicin.
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