Selenium sulfide

Selenium sulfide (CAS 56093-45-9) is an inorganic compound used as an active antifungal and antimicrobial agent in medicated personal care and pharmaceutical formulations.

Where is Selenium sulfide used?

• Medicated shampoos and scalp treatments: active ingredient at 1% to 2.5%
• Prescription-grade products: higher concentrations
• Topical lotions and creams for dermatological antifungal conditions
• Agricultural crop protection and pest management: biocidal agent
• Antimicrobial preservation systems: fungal control
• It targets the fungal organisms responsible for dandruff, seborrheic dermatitis, and tinea versicolor.
• Formulated as a suspension or dispersion because of low water solubility, requiring surfactants and particle size control for homogeneity.
• Suspension-based shampoos and lotions may need rheology modifiers to prevent settling and ensure uniform distribution during use.

Good to know: USP and BP grades support regulated drug product manufacturing; technical-grade material serves non-pharmaceutical industrial applications where compendial specifications are not required.

Formulation notes

• A micronized 0.6% form has been shown to be effective for dandruff.
• In an in vitro study, 2.5% was equivalent to both 1% and 2% zinc pyrithione in sporicidal activity.
• Cold permanent wave liquids (alkaline permanent wave liquids) can impair the efficacy of selenium sulfide shampoo.

Typical specification

• Micronized powder has a controlled particle size of less than 10 microns.
• For API supply, must meet regional pharmacopoeia or quality standards with focus on material identity, particle size control and impurity profiling for topical formulations.

Regulatory status

• EC (EG) number is 231-303-8.
• Classified under ATC code D01AE13.
• Classified as acute toxicity category 3.
• Carries hazard statement H400: very toxic to aquatic life.

Storage, packaging and handling

• May discolor and is sensitive to oxidation or pH changes, so formulations typically use stabilizing excipients and protective packaging.
• Should be stored in a well-ventilated place with the container tightly closed.

Frequently asked questions about Selenium sulfide

What is the mechanism of action of selenium sulfide?

It acts as an antimitotic by reducing thymidine incorporation into dermal epithelial cell DNA, thereby slowing epidermal cell turnover.

Against which organisms is selenium sulfide active?

It shows sporicidal activity against Trichophyton tonsurans and is active against Pityrosporum orbiculare, a lipophilic yeast responsible for pityriasis versicolor.

What is the regulatory status of selenium sulfide in cosmetics?

It is listed in UK cosmetics regulations Annex II as a prohibited substance.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.