The ingredient, explained
Sodium Hydroxide
A human experiment tested sodium hydroxide as an irritant.
Ingredient guide
What it is and what it does
Sodium hydroxide has a recorded buffering role in cosmetics, meaning it is used in controlling a formula's pH. The final product's pH cannot be read from its position in the ingredient list.
About this ingredient: CosIng identity and functions via Open Beauty Facts ↗ · European Commission ingredient function definitions ↗
- Buffering
- Helps resist changes in a formula's pH.
- Denaturant
- Makes a product unpalatable, often in alcohol-containing formulas.
Function definitions: European Commission ingredient function definitions (SCCNFP/0299/00, pages 16 to 20) ↗
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 topical research
Experimental sodium hydroxide exposure caused strong irritation and early discontinuation at many test sites.
What this does not tell us
This deliberate irritation model cannot predict the effects of a finished product whose pH has been adjusted and whose hydroxide has reacted.
Sources for this summary. PubMed 15541082 ↗
Research review checked Oct 1, 2026
Bounded review of 9 local candidate records, selected relevant abstracts, and targeted exact-name primary-source searches. Not a systematic review.
Ingredient research is not proof that a product containing this ingredient works.
Read the 1 selected study
Human topical research · n=19
Fruit acids and sodium hydroxide in the food industry and their combined effect with sodium lauryl sulphate: controlled in vivo tandem irritation study. ↗
The British journal of dermatology · 2004
Follow the formula
Products containing this ingredient
From the Serenfold edit. Linked by the ingredient list, without an efficacy ranking.
Names and identifiers
Registry identity
Sodium hydroxide
- INCI name on ingredient lists
- SODIUM HYDROXIDE
- CAS registry number
- 1310-73-2
- EC number
- 215-185-5
Other recorded names (1)
- natrii hydroxidum
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
- European Commission ingredient function definitions ↗ · Recorded Sep 30, 2026