The ingredient, explained
Phenylbenzimidazole Sulfonic Acid
A controlled human formulation test examined added phenylbenzimidazole sulfonic acid.
Ingredient guide
What it is and what it does
Phenylbenzimidazole Sulfonic Acid is the aromatic organic compound that conforms to the formula:
About this ingredient: EU CosIng ingredient registry (via Open Beauty Facts taxonomy) ↗
- UV filter
- Filters some UV radiation. The ingredient label does not establish a finished product's SPF or UVA protection.
- Light stabilizer
- Helps protect the cosmetic formula against deterioration caused by light. This product-stability role does not establish a finished product's SPF.
- Uv absorber
- Protects the formulation against UV light. This role is distinct from a skin-protecting UV filter.
Function definitions: European Commission ingredient function definitions (SCCNFP/0299/00, pages 16 to 20) ↗ · BASF: Light stabilization of cosmetic formulas ↗
Registry functions describe possible formulation roles, not results for a finished product. A dictionary entry is not an approval or a safety assessment.
A closer look
What the research shows
Human research on a combination
Adding the filter prevented phototoxic reactions in seven of eight subjects who reacted to benzoyl peroxide alone.
What this does not tell us
Controlled double-blind formulation experiment in 18 subjects; not isolated filter SPF/UVA efficacy or general sunscreen safety.
Sources for this summary. PubMed 3408262 ↗
Research review checked Oct 1, 2026
Bounded review of local candidates, exact-name indexed primary journal/PubMed safety and topical searches; not a systematic review.
Ingredient research is not proof that a product containing this ingredient works.
Read the 1 selected study
Human research on a combination · n=18
Prediction of benzoyl peroxide phototoxicity by photoepidermotests after repeated applications. Preventive value of a UVB filter. ↗
Archives of dermatological research · 1988
Follow the formula
Products containing this ingredient
From the wider catalogue. Linked by the ingredient list, without an efficacy ranking.
Names and identifiers
Registry identity
Phenylbenzimidazole Sulfonic Acid is the aromatic organic compound that conforms to the formula:
- INCI name on ingredient lists
- PHENYLBENZIMIDAZOLE SULFONIC ACID
- CAS registry number
- 27503-81-7
- EC number
- 248-502-0
Sources for this ingredient record
- EU CosIng ingredient registry (via Open Beauty Facts taxonomy) ↗ · ODbL 1.0 (Open Beauty Facts database) · Recorded Aug 8, 2026