Is Sodium Hydroxide safe in cosmetics?
Sodium Hydroxide has a safety rating of "POOR" in our database. EU status: restricted. US status: restricted.
Sodium Hydroxide
Also known as: Na(OH), Sodium hydroxide (Na(OH)), Caswell No. 773, Caustic soda, liquid, EINECS 215-185-5 (+15 more)
INCI: SODIUM HYDROXIDE
Sodium Hydroxide (CAS 1310-73-2) is a cosmetic active ingredient functioning as alkali; cuticle-swelling agent; disulfide bond-breaking agent. EU Regulation 1223/2009 status: restricted, max Annex III entry 25: max 3.0% as hair straightener in professional products; max 2.0% in general consumer products; pH limits apply. Not for children.; GHS signal word DANGER. Industrial safety data is also available in the chemical safety database. Same-CAS public records also appear in industrial chemical safety, pharmaceutical, and food safety data.
Cross-Vertical Regulatory Divergence
Sodium Hydroxide is classified GHS Danger (H290, H314, H315, H318, H319) in the chemicals database but is restricted in EU cosmetics at max Annex III entry 25: max 3.0% as hair straightener in professional products; max 2.0% in general consumer products; pH limits apply. Not for children..
Source: Cosmetics: ingredients.eu status/eu max; Chemicals: ghs classifications.signal word/hazard statement code
Function
alkali; cuticle-swelling agent; disulfide bond-breaking agent (lanthionization); pH modifier
Editorial assessment
POOR
Preliminary editorial note — not a computed safety verdict.
Regulatory Status
EU EU Status
restricted
EU Max Conc.
Annex III entry 25: max 3.0% as hair straightener in professional products; max 2.0% in general consumer products; pH limits apply. Not for children.
US US Status
restricted
US Notes
Permitted in hair relaxer formulations as active at pH 12–14. NIEHS Sister Study (2022, EPH) found women using chemical straighteners ≥4x/year faced HR 2.55 for uterine cancer. JNCI 2026 follow-up linked frequent use to pancreatic cancer (HR 2.66), thyroid cancer (HR 1.71), and NHL (HR 1.62). FDA has not yet issued a formal ban but cancer findings have triggered significant regulatory and litigation scrutiny.
For full compliance data across multiple jurisdictions, use the Substance Compliance tool.
Safety Data
Margin of Safety, dermal absorption, and sensitization profile summaries for Sodium Hydroxide.
Calculate MoS for your specific formulation with the MoS Calculator.
GHS Hazard Classification
Globally Harmonized System classification per ECHA C&L inventory and ILO/WHO International Chemical Safety Cards.
Signal Word
DANGER
Pictograms
CorrExcl markWarn
Hazard Statements
Harmful if swallowed Causes severe skin burns and eye damage May cause respiratory irritation
Short-term Exposure Effects
The substance is corrosive to the eyes, skin and respiratory tract. Corrosive on ingestion.
Long-term Exposure Effects
Repeated or prolonged contact with skin may cause dermatitis.
Routes of Exposure
Serious local effects by all routes of exposure.
EPA ToxValDB — Toxicity Values
10 toxicity values from EPA ToxValDB (aggregated from CCTE, HPV, ToxRefDB, IRIS, and other regulatory dossiers).
| Endpoint | Value | Species | Route | Duration | Source |
|---|---|---|---|---|---|
| LOAEL | =0.5 mg/m3 | Human | inhalation | acute | Cal OEHHA REL derivations |
| LOEL | =2 % w/v | European Rabbit | dermal | acute | ECOTOX |
| LOEL | =8 % w/v | European Rabbit | dermal | acute | ECOTOX |
| NOEL | =2 % w/v | European Rabbit | dermal | acute | ECOTOX |
| NOEL | =0.1 mM | Rat | oral | short-term | ECOTOX |
| NOEL | =0.1 mM | Rat | oral | short-term | ECOTOX |
| LEL | =2 mg/m3 | Human | inhalation | acute | NIOSH IDLH |
| LD50 | =40 mg/kg | Mouse | injection | - | ECHA |
| LOEL | =200 mM | Rat | oral | acute | ECOTOX |
| LOEL | =5 % | Rat | oral | chronic | ECOTOX |
EU CLP Annex VI Harmonized Classification
Legally binding harmonized classification per Regulation (EC) No 1272/2008 (CLP) Annex VI.
Signal Word
Danger
Pictograms
Corrosive
Hazard Class and Category
Skin Corr. 1A
Hazard Statements
- H314 Causes severe skin burns and eye damage
Specific Concentration Limits / M-factors
Skin Corr. 1A; H314: C ≥ 5.0%; Skin Corr. 1B; H314: 2.0% ≤ C < 5.0%; Skin Irrit. 2; H315: 0.5% ≤ C < 2.0%; Eye Irrit. 2; H319: 0.5% ≤ C < 2.0%
Inserted via ATP: CLP00
ECHA REACH Registration
European Chemicals Agency REACH dossier and Substances of Very High Concern listing.
Registration Type
Full
Tonnage Band
10,000,000 - 100,000,000 tonnes
Substance Type
SUBSTANCE; GROUP
SVHC Candidate
No
Hazard classification: Restricted (Annex XVII)
Expanded Jurisdictional Detail
Additional regulatory detail beyond the 7-jurisdiction summary: Saudi SFDA, Korea MFDS, ASEAN ACD, Japan/Korea, Brazil/India, and cross-jurisdictional restriction entries.
Additional Jurisdictional Restrictions (2)
| Jurisdiction | Status | Max % | Product Type |
|---|---|---|---|
| CN | restricted | - | Hair straightening / depilatories |
| BR | restricted | 2 (gen) / 4.5 (prof) | a) Hair relaxers/straighteners: gen use 1) 2%, prof use 2) 4.5% (as NaOH mass); b) Depilatories: up to pH 12.7; c) Other products: up to pH 11 |
Typical Use Concentrations
Reported concentration ranges per product category from SCCS/CIR/industry sources.
| Product Category | Typical Range | Max Reported | Source |
|---|---|---|---|
| Face Cream | 0.01–0.5 | 5 | CIR Safety Assessment |
| Shampoo | 0.01–0.5 | 5 | CIR Safety Assessment |
Function Categories & List Membership
Cosmetic/Chemical Function Categories
Binder
Biocide
Catalyst
Chelating agent
Cleaning agent
Dye
Filler
Flavouring and nutrient
Food preservative
Fragrance
Regulatory List Membership (5)
EU Regulated in Personal Care
EU Restricted for Children (Cosmetics)
IFRA Fragrance Transparency List
EPA Safer Chemical Ingredients List (SCIL)
FDA Substances Added to Food (EAFUS)
Editorial summary
Preliminary editorial summary for Sodium Hydroxide — not a computed safety verdict. See the sourced toxicological data above.
Regulatory Flags
annex-iii
restricted
extreme-alkalinity
scalp-burn-risk
cancer-risk-signal
niehs-sister-study-2022
jnci-2026
uterine-cancer-hr-2.55
pancreatic-cancer-hr-2.66
endocrine-disruptor-coformulant-pathway
professional-only-eu
childhood-exposure-concern
enhanced-percutaneous-absorption
eu_children_restricted
epa_safer_alternative
ifra_fragrance
fda_food_additive
jecfa_safe
Known Synonyms
Na(OH)
Sodium hydroxide (Na(OH))
Caswell No. 773
Caustic soda, liquid
EINECS 215-185-5
EPA Pesticide Chemical Code 075603
Fuers Rohr
Lewis-red devil lye
Liquid-plumr
Rohrputz
Rohrreiniger Rofix
Soda, hydrate
Sodium hydroxide dimer
Soda, kaustische
Natrium causticum
Natrium-hydroxid, reinstes
Natriumhydroxyde
Sodio(idrossido di)
Sodium(hydroxyde de)
UNII-55X04QC32I
Chemical Function
pH regulating agent
Regulatory Lists
active_ingredient; agricultural; applied; Pesticides
animal_products
Journal of Chemical Engineering & Process Technology
pharmaceutical
drinking_water; Europe; manufacturing; plastic_additive
active_ingredient; Pesticides
active_ingredient; Pesticides
active_ingredient; Pesticides
active_ingredient; Pesticides
active_ingredient; Pesticides
active_ingredient; Pesticides
active_ingredient; Pesticides
active_ingredient; Pesticides
active_ingredient; Pesticides
active_ingredient; Pesticides
active_ingredient; Pesticides
active_ingredient; Pesticides
active_ingredient; Pesticides
Australian Status
AICIS status: listed
Cross-Vertical Safety Context
Same-CAS public records found in pharmaceutical and food safety data.
SOURCE
ChEMBL / DrugCentral / FAERS
DB_PHARMA CAS match
Pharmaceutical Data
Same-CAS rows from the pharmaceutical spoke database.
Compound
SODIUM HYDROXIDE
ChEMBL ID
CHEMBL2105794
Max Phase
-1
Adverse Event Associations
8
SOURCE
EFSA / FDA GRAS
food_additives
Food Safety Data
Same-CAS food additive or FDA GRAS records from the core public database.
Food Name
Sodium hydroxide
E Number
E524
ADI
NOT LIMITED mg/kg bw
Food Category
preservative
Frequently Asked Questions
Is Sodium Hydroxide allowed in the EU?
Sodium Hydroxide EU regulatory status: restricted. Maximum allowed concentration: Annex III entry 25: max 3.0% as hair straightener in professional products; max 2.0% in general consumer products; pH limits apply. Not for children.. This is based on EU Regulation 1223/2009 and its amendments.
What does Sodium Hydroxide do in cosmetics?
Sodium Hydroxide functions as: alkali; cuticle-swelling agent; disulfide bond-breaking agent (lanthionization); pH modifier. It is classified as a Active Ingredient in our database. CAS number: 1310-73-2.
Is Sodium Hydroxide classified as hazardous under GHS?
Sodium Hydroxide carries a GHS signal word of "DANGER". Hazard statements: Harmful if swallowed Causes severe skin burns and eye damage May cause respiratory irritation. This classification is based on the ILO/WHO International Chemical Safety Card and ECHA C&L inventory data. Note: GHS classification applies to the pure substance — at cosmetic use concentrations, hazard thresholds may not be met.
Is Sodium Hydroxide used outside cosmetics?
Sodium Hydroxide also appears in industrial chemical safety, pharmaceutical, and food safety data. The cross-vertical cards on this page render same-CAS public rows from the matched databases.
Does Sodium Hydroxide have different safety status in cosmetics vs industrial chemicals?
Sodium Hydroxide is classified GHS Danger (H290, H314, H315, H318, H319) in the chemicals database but is restricted in EU cosmetics at max Annex III entry 25: max 3.0% as hair straightener in professional products; max 2.0% in general consumer products; pH limits apply. Not for children..
Compliance Tools
Check Sodium Hydroxide compliance across multiple jurisdictions:
Ingredient Decoder
Paste a full ingredient list for instant analysis
82 Allergen Checker
Check for EU declarable fragrance allergens
Substance Compliance
Check compliance across multiple jurisdictions
MoS Calculator
Calculate Margin of Safety using SCCS methodology
Heavy Metal Limits
Compare limits across jurisdictions
Related Ingredients
Acetyl Tetrapeptide-5
EXCELLENT
Same category
Anti-edema peptide for periorbital ar...
Activated Charcoal
EXCELLENT
Same category
Adsorbent; skin cleanser; pore-cleans...
Adenosine
EXCELLENT
Same category
Skin-conditioning agent, anti-aging, ...
Allantoin
EXCELLENT
Same category
Skin conditioner, keratolytic, anti-i...
Alpha-Glucan Oligosaccharide
EXCELLENT
Same category
prebiotic, skin-conditioning
Ascophyllum Nodosum Extract
EXCELLENT
Same category
Skin Brightening, Tyrosinase Inhibito...
1,2,4-Benzenetriacetate
POOR
Similar safety
Hair dye precursor (triacetyl ester o...
1,2,4-Trihydroxybenzene
POOR
Similar safety
Hair colorant (auto-oxidative dye)
1,3-Bis-(Isocyanatomethyl) Cyclohexane
POOR
Similar safety
Monomer / cross-linking agent used in...
1,4-Butanediol
POOR
Similar safety
Solvent, humectant, viscosity control...
1,6-Hexamethylene Diisocyanate (HDI)
POOR
Similar safety
Monomer and crosslinker in polymer sy...
1,6-Hexanediamine
POOR
Similar safety
Industrial chemical (nylon monomer); ...
Germanium Dioxide
POOR
Chemical family
Skin conditioning; also used in elect...
Lithium Hydroxide
POOR
Chemical family
Buffering / pH adjuster / hair straig...
SODIUM (ASTROCARYUM VULGARE/EUTERPE OLERACEAE/PALM) FRUIT/(ASTROCARYUM VULGARE/PALM) KERNEL/(ASTROCARYUM MURUMURU/BABASSU/BERTHOLLETIA EXCELSA/CARAPA GUIANENSIS/COCOA/FEVILLEA TRILOBATA/PASSIFLORA EDULIS/THEOBROMA GRANDIFLORUM) SEEDATE
GOOD
Browse nearby
Cleansing, Surfactant - Cleansing
Is Sodium Hydroxide in Your Products?
Scan any product label with Piro — our free ingredient scanner. Point your camera at the ingredients list and get instant safety scores for every ingredient.
Try Piro Free →Analyze Your Full Ingredient List
Paste any INCI list into the Decoder for instant safety analysis, or calculate the Margin of Safety for Sodium Hydroxide in your formulation.