CosIng Checker
CosIng Checker
EU cosmetic ingredients, restrictions and safety
Login
Annex III Entry 15a 11/01/2024

POTASSIUM HYDROXIDE / SODIUM HYDROXIDE

Potassium or sodium hydroxide

POTASSIUM HYDROXIDE / SODIUM HYDROXIDE is listed in Annex III and may only be used under the conditions shown in this record. Maximum concentration in this record: (a) 5% (b) 2% (General use) and 4.5% (Professional use) Entry 15d: 1,5%.

Search similar Back to annex Compare
Restricted substance— Annex III, EU Regulation 1223/2009
Max conc.: (a) 5% (b) 2% (General use) and 4.5% (Professional use…
Entry: 15a

Record details

Maximum concentration

(a) 5% (b) 2% (General use) and 4.5% (Professional use) Entry 15d: 1,5%

Product type

Nail cuticle solvent Hair straightener PH adjuster for depilatories Other uses as pH adjuster Callosity softener/remover (entry 15d)

Other restrictions

(b)
1. General use
2. Professional use
(c) up to pH 12.7
(d) up to pH 11

15 d Contains alcakali, Avoid contact with eyes
Keep out of reach of chindren ans Read directions for use carefully

Warnings

(a) Contains alkali
Avoid contact with eyes
Can cause blindness
Keep out of reach of children
(b) 1. Contains alkali
Avoid contact with eyes
Can cause blindness
Keep out of reach of children
2. For professional use only
Avoid contact with eyes
Can cause blindness
(c) Keep out of reach of children
Avoid contact with eyes

INCI glossary name

POTASSIUM HYDROXIDE / SODIUM HYDROXIDE

Chemical name

Potassium or sodium hydroxide

Regulatory information

Regulation

(EU) 2016/622

Identified ingredients

Key data

CAS
1310-58-3 / 1310-73-2
EC
215-181-3 / 215-185-5
Annex
III
Entry number
15a

Inventory links for POTASSIUM HYDROXIDE / SODIUM HYDROXIDE

Direct matches are limited for this record, so nearby entries from Annex III are shown as well.

Annex III 14
Nearby record in the same annex

HYDROQUINONE

CAS: 123-31-9
EC: 204-617-8
Annex III 11
Nearby record in the same annex

DICHLOROPHEN

CAS: 97-23-4
EC: 202-567-1
Annex III 16
Nearby record in the same annex

1-NAPHTHOL

CAS: 90-15-3
EC: 201-969-4
Annex III 16
Nearby record in the same annex

1-Naphthol

CAS: 90-15-3
EC: 201-969-4
Annex III 17
Nearby record in the same annex

SODIUM NITRITE

CAS: 7632-00-0
EC: 231-555-9

What Annex III means for POTASSIUM HYDROXIDE / SODIUM HYDROXIDE

POTASSIUM HYDROXIDE / SODIUM HYDROXIDE is a restricted substance under Annex III of EU Cosmetics Regulation 1223/2009. Its use in cosmetics is only permitted under the specific conditions set out in the entry above, including applicable concentration limits, product type restrictions and required warning statements.

When including this substance in a formulation, all conditions — maximum concentration, product scope and warning labels — must be met simultaneously. Compliance with one condition does not override the others.

This record is linked to 2 CosIng inventory ingredients for name and identifier cross-reference. The page also surfaces 11 related annex records with overlapping identifiers, annex logic or naming patterns.

Compliance checklist

  • Ensure formulation concentration does not exceed: (a) 5% (b) 2% (General use) and 4.5% (Professional use) Entry 15d: 1,5%
  • Confirm product type compatibility: (a) Nail cuticle solvent (b) Hair straightener (c) pH adjuster for depilatories (d) Other uses as pH adjuster Callosity softener/remover (entry 15d)
  • Include required warning statement on product label.
  • Document conditions of use in the Product Information File (PIF).

Frequently asked questions

POTASSIUM HYDROXIDE / SODIUM HYDROXIDE is listed in Annex III of EU Regulation 1223/2009 as a restricted substance. It may only be used under the conditions specified in the entry, including any maximum concentration, product type limitation and required warning statements shown above.

CAS 1310-58-3 / 1310-73-2 is the unique numerical identifier assigned to POTASSIUM HYDROXIDE / SODIUM HYDROXIDE by the Chemical Abstracts Service. In cosmetic compliance work, the CAS number is used to cross-reference the substance across regulatory databases, raw material specifications and safety assessment reports. Multiple EU annex entries may share the same CAS number if the same substance appears under different conditions or in different annexes.

The maximum concentration of (a) 5% (b) 2% (General use) and 4.5% (Professional use) Entry 15d: 1,5% applies to the concentration of the substance in the ready-to-use cosmetic product. When the substance is supplied as part of a blend or mixture, the calculation must account for the contribution of all sources in the formulation. The combined concentration must not exceed the stated limit.

Use the INCI Checker tool on this site to paste your full ingredient list (INCI) and scan it against all Annex II–VI entries. The tool highlights any ingredients that match restricted, prohibited or allergen-flagged records. This is useful for rapid compliance screening of finished product formulas or raw material declarations.
Open INCI Checker

Source note for Annex III record POTASSIUM HYDROXIDE / SODIUM HYDROXIDE

This page summarizes one Annex III record for POTASSIUM HYDROXIDE / SODIUM HYDROXIDE from public European Commission cosmetic materials and adds linked inventory or identifier matches when available.

Use this record page to review Annex III conditions for POTASSIUM HYDROXIDE / SODIUM HYDROXIDE, but confirm any final regulatory decision against the current official annex wording and source files.

View sourcesView updates

Tools & next steps

Check your formula

Paste a full INCI list to detect POTASSIUM HYDROXIDE / SODIUM HYDROXIDE and other flagged EU annex records in one pass.

INCI Checker

Compare entries

Compare POTASSIUM HYDROXIDE / SODIUM HYDROXIDE side by side with another annex record to review differences in restrictions, concentrations and annex placement.

Compare

Browse the annex

See all records in Annex III and compare regulatory conditions across substances in this annex.

Open Annex III