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SODIUM HYDROXIDE

Last update on Dec 3, 2025

Sodium Hydroxide, also called Iye or Caustic Soda, is a potent alkaline compound used in cosmetics to adjust the pH of products. It can neutralize acidic ingredients and make products safe and comfortable for the skin. Sodium Hydroxide is also used in sapofication (soap making) where it reacts with oils or fats and converts them into soap. However, this ingredient is very strong and has a corrosive base in its pure form, which is why it is only safe in cosmetics when used at really low concentrations. Higher levels may be used in hair relaxers used to straighten tightly curled hair. Sodium Hydroxide is also often found in cleansers, face wash, moisturizers, serums, toners, soap, and shampoos.

CAS Number: 1310-73-2Chem/IUPAC Name: Sodium hydroxideEINECS/ELINCS No: 215-185-5COSING REF No: 37890

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Liposomal glycolic acid 10%

by Lipomize

Sustainable option
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Liposomal lactobionic acid 10%

by Lipomize

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Extremosio™

by DKSH

Sustainable option
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What is SODIUM HYDROXIDE used for?

Buffering agent - Sodium Hydroxide is primarily used in cosmetics to adjust and control pH. It neutralizes excess acids in a formula, keeping products within a stable skin-safe pH range.
Denaturant - Sodium Hydroxide alters ethanol’s taste and chemical character so it no longer qualifies as drinkable alcohol. This helps meet regulatory requirements for “Alcohol Denat.” in cosmetic formulations.
Emulsifier - Sodium Hydroxide helps maintain the viscosity and stability of creams and lotions. It also neutralizes fatty acids to create soap-like molecules, stabilizing oil-in-water emulsions.

Origin

Sodium Hydroxide is mainly produced through the chlor-alkali process, where a saltwater (brine) solution is electrolyzed. During electrolysis, chlorine gas forms at the anode, while sodium ions combine with water at the cathode to create sodium hydroxide and hydrogen gas. The NaOH solution is then purified, concentrated, and solidified. In its raw form, Sodium Hydroxide appears as white, odorless crystals.

What does SODIUM HYDROXIDE do in a formulation?

BUFFERING|

DENATURANT|

EMULSIFYING

Safety Profile

Sodium Hydroxide can be safe for use when used at very low, controlled concentrations. Recommended levels are 2% to 5% for rinse-off products and 0.25% for leave-on products. Being very strong, higher concentrations may cause chemical burns. It is also unsafe for use around the eye area. A medical professional should be consulted in case of accidental ingestion. Patch testing is recommended prior to full application, especially in cases of sensitive skin.