Zinc pyrithione

Zinc pyrithione at a glance

Zinc pyrithione is a well-known ingredient in hair care, most often in shampoos. The supplier specification describes this grade as a viscous liquid and lists it as working in water. In practice, zinc pyrithione itself is barely soluble, so liquid grades are usually fine dispersions that need to be kept evenly mixed. The supplier CoA confirms the concentration, the full INCI and the recommended level for each lot.

Check the rules first

This ingredient needs a regulatory check before any formula work. In the European Union, zinc pyrithione has not been permitted in cosmetic products since March 2022, so products containing it cannot be sold there as cosmetics. In the United States, the ingredient is used in shampoos that control dandruff, and those claims place the product under the OTC monograph rules, with specific labeling, active levels and manufacturing requirements. Other markets have their own lists. Confirm the rules for every country on your sales list before you start.

Where it is used

Shampoos

Shampoos are the main format. The dispersion is added to the surfactant base, and a suspending system keeps the particles evenly distributed so each dose contains the same amount.

Scalp care products

Some markets also allow leave-on scalp products. These need careful checks of the permitted level and labeling.

Handling the dispersion

Shake or stir the container before weighing, because particles can settle. Add the dispersion to the shampoo base with moderate stirring, after the main surfactants are combined. A suspending agent such as an acrylates copolymer or a structured surfactant system helps prevent settling in the bottle. Keep the pH and processing conditions within the supplier guidance.

Compatibility

Zinc pyrithione can react with some chelating agents and metal ions, which may change its color, so review the formula with the supplier data. Avoid strong oxidizers. For a scalp-care routine, a separate conditioner with IO L-Arginine Powder or a scalp tonic with Menthol Liquid can complete the line. Related scalp and hair options sit in our actives catalog.

Testing

Check that the dispersion stays suspended over time at room temperature and in a warm cabinet. Watch for color changes and settling at the bottom of the bottle. If you sell in the US under the monograph, follow its testing and documentation steps.

Labeling

Copy the full INCI and the concentration from the CoA. For US products under the monograph, use the required facts panel format and approved claim wording. For other markets, confirm whether the ingredient is allowed at all.

Characteristics

Form: viscous liquid. Solubility: listed as water; in practice a fine dispersion. Main use: shampoos. Regulatory: not allowed in EU cosmetics since March 2022; dandruff-control claims in the US fall under the OTC monograph. INCI, concentration and level: supplier CoA.

Original recipe: shampoo base for a US monograph product, 100 g

Distilled water 61.20 g, sodium laureth sulfate 70% 18.00 g, cocamidopropyl betaine 8.00 g, acrylates copolymer 5.00 g, zinc pyrithione dispersion 4.00 g, glycerin 1.50 g, sodium chloride 1.00 g, preservative 0.50 g, fragrance 0.80 g. Combine water and surfactants, add the polymer and neutralize, then add the dispersion and the rest with moderate stirring.

Planning the product

Because the rules differ so much between markets, decide on the sales countries first and only then start the formula. A brand selling mainly in the US can plan a monograph shampoo, while a brand selling in Europe needs another approach for scalp care. Keep a short regulatory note in the product file that records the decision, the date and the sources checked, and review it each year, since rules on this ingredient have changed before.

Storage

Store closed in a cool place away from light. Shake well before each use.