The ingredient, explained
Calcium Hydroxide
A published expert safety assessment covers this exact ingredient.
Ingredient guide
What it is and what it does
Calcium dihydroxide
About this ingredient: EU CosIng ingredient registry (via Open Beauty Facts taxonomy) ↗
- Buffering
- Helps resist changes in a formula's pH.
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
Safety assessment
Panel judged calcium hydroxide safe in hair straighteners/depilatories under recommended conditions with minimized skin contact; other assessed uses require non-irritating formulations.
What this does not tell us
Strong alkalinity and product/use restrictions matter. Group safety, not skin-conditioning benefit. Dental pulpotomy trial is not cosmetic evidence.
Sources for this summary. PubMed 34514896 ↗
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
Safety assessment
Safety Assessment of Inorganic Hydroxides as Used in Cosmetics. ↗
International journal of toxicology · 2021
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
Calcium dihydroxide
- INCI name on ingredient lists
- CALCIUM HYDROXIDE
- CAS registry number
- 1305-62-0
- EC number
- 215-137-3
Other recorded names (1)
- calcii 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