Pyrithione zinc
Pyrithione zinc suppliers and sourcing guide
Pyrithione zinc is a coordination complex of zinc with two pyrithione (1-hydroxy-2-pyridinethione) ligands, made synthetically from a pyridine N-oxide intermediate and a zinc salt. It is almost insoluble in water, so it is sold as a fine white to off-white powder or, more often, as an aqueous dispersion of about 48% solids. Brands buy it for shampoos, scalp treatments and bar soaps where it is the declared OTC active.
- Category
- Cosmetic actives
- Also known as
- Zinc pyrithione · ZPT · Bis(1-hydroxy-2(1H)-pyridinethionato)zinc · CAS 13463-41-7
- Facts checked
- November 2026
Forms and grades of pyrithione zinc
Suppliers sell different products under the same name. Specify the one you need.
Aqueous dispersion
A pumpable suspension, commonly around 48% pyrithione zinc, with a set particle size and dispersant. The most common form for shampoo plants.
Powder
Dry pyrithione zinc for anhydrous or bar products; needs good dispersion and dust control.
Particle-size grades
Grades with different median particle sizes or platelet shapes, which change deposition and suspension stability.
Pharmacopeial grade
Material meeting a USP monograph, used where the finished product is an OTC drug.
What to check on the COA
Compare each result with your own specification when the lot arrives.
- Assay
- Pyrithione zinc content by iodometric titration or HPLC, as percent of the powder or dispersion.
- Zinc content
- Zinc by titration or ICP, a check on the complex ratio.
- Particle size
- Median and upper particle size by laser diffraction, which affect deposition and settling.
- Related substances
- Free pyrithione, pyrithione disulfide and other impurities by HPLC.
- Dispersion properties
- Solids, pH and viscosity for dispersions.
- Heavy metals
- Lead, cadmium and other metals by ICP-MS.
Storage, lots and expiry
Storage and shelf life
Keep pyrithione zinc away from light and from iron and copper, which can discolor it; stainless steel or lined containers are standard. Dispersions must not freeze and should be mixed before sampling because solids settle. Shelf life is set by the supplier, with reassay of active and particle size for older stock.
Lots and expiry dates
Record assay and particle size for each lot, because particle size shifts suspension stability and finished-product appearance. Watch for discoloration from metal contact, and rotate dispersions before they settle hard.
Regulatory status
Facts from regulators and standards bodies, each linked to its source.
21 CFR 358.710 lists pyrithione zinc as an OTC monograph active for dandruff products at 0.3 to 2 percent in rinse-off products and 0.1 to 0.25 percent in leave-on products.
Source: ecfr.gov (opens in a new tab)Health Canada's Anti-Dandruff Products Monograph lists pyrithione zinc at 0.1 to 0.25% for leave-on and 0.3 to 2% for rinse-off products.
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.
Pyrithione zinc suppliers
Manufacturers and distributors whose own websites say they sell it.
We are checking pyrithione zinc 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 pyrithione zinc? Request a listingFrequently asked questions
What forms of pyrithione zinc can brands buy?
Common forms include aqueous dispersion, powder, particle-size grades and pharmacopeial grade. Ask each supplier for the specification sheet of the exact grade they quote.
What should the COA for pyrithione zinc include?
Expect assay, zinc content, particle size, related substances, dispersion properties and heavy metals, each with its method, specification and result for that lot.
How should pyrithione zinc be stored?
Keep pyrithione zinc away from light and from iron and copper, which can discolor it; stainless steel or lined containers are standard. Dispersions must not freeze and should be mixed before sampling because solids settle. Shelf life is set by the supplier, with reassay of active and particle size for older stock.
What is the regulatory status of pyrithione zinc?
21 CFR 358.710 lists pyrithione zinc as an OTC monograph active for dandruff products at 0.3 to 2 percent in rinse-off products and 0.1 to 0.25 percent in leave-on products. Health Canada's Anti-Dandruff Products Monograph lists pyrithione zinc at 0.1 to 0.25% for leave-on and 0.3 to 2% for rinse-off products.
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