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Skincare Ingredient

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Sodium Hydroxide

In Skincare: Is Sodium Hydroxide Safe? Comedogenic Rating & Side Effects

Safety (overall safety)
2/5 — Low risk
Irritancy (skin irritation)
4/5 — High risk

Safety Information

The Cosmetic Ingredient Review (CIR) Expert Panel has determined that sodium hydroxide is safe in cosmetics when used in formulations under proper manufacturing controls to ensure it is neutralized and not present in the final product at a high pH.

Quick Insights

At a glance

  • 01

    Sodium hydroxide is a highly alkaline ingredient.

  • 02

    In cosmetics like exfoliants and cleansers, sodium hydroxide is used in small amounts to adjust the pH of a formulation.

  • 03

    Sodium hydroxide helps maintain the pH in hair and nail products.

  • 04

    Also known as lye, sodium hydroxide is an inorganic compound.

Overview

Ingredient Profile

Sodium hydroxide, a highly alkaline compound, is used in cosmetics to adjust the pH of formulations like cleansers and exfoliants, ensuring optimal product efficacy. Typically used in very small quantities, it helps maintain a specific pH range crucial for these products to function effectively. While pure sodium hydroxide has a high pH, it is used in cosmetics at levels up to pH 11 and can act as a cleansing or denaturing agent. Higher concentrations (above 10%) may cause skin sensitization.
Classifications
pH Adjuster/Stabilizer

Data & Research

Scientific Facts

Sodium hydroxide, also known as caustic soda or sodium hydrate, has a long history of use in saponification – the process of converting fats into soap. Calcium hydroxide is also known as hydrated lime, and its mineral form is portlandite. Magnesium hydroxide is commonly referred to as milk of magnesia, with brucite being its mineral form. Potassium hydroxide is also known as potash lye or caustic potash, and it exhibits hygroscopic properties – meaning it attracts and absorbs water molecules from its surroundings, eventually dissolving in the absorbed water.

Common Uses

Formulation in Sodium Hydroxide

Sodium hydroxide, calcium hydroxide, magnesium hydroxide, and potassium hydroxide are primarily used to adjust and maintain the pH levels of cosmetic and personal care formulations. Magnesium hydroxide is also employed as an absorbent ingredient.

Role of Sodium Hydroxide

Active Cosmetic Mechanisms

BUFFERING

pH Stabilizer

Maintains stable pH levels in products

SCIENTIFIC ANALYSIS

// Evidence: Buffering systems resist pH changes through weak acid-conjugate base pairs (citric acid/sodium citrate, lactic acid/sodium lactate, phosphate salts) that operate within specific pH ranges based on their pKa values. The mechanism follows the Henderson-Hasselbalch equation, with buffer components neutralizing added H⁺ or OH⁻ ions. Proper buffering prevents pH drift and maintains efficacy.

DENATURANT

Alcohol Treatment Agent

Makes alcohol undrinkable in cosmetic products

SCIENTIFIC ANALYSIS

// Evidence: Denaturants are added to ethanol to render it unfit for consumption while maintaining cosmetic functionality. Common denaturants include denatonium benzoate (extremely bitter), diethyl phthalate, and tert-butyl alcohol. This allows manufacturers to use tax-free specially denatured alcohol. Denaturants must meet specific regulatory formulations with precise ratios.

Products

containing Sodium Hydroxide

18207 formulations
Skin Perfecting 2% BHA Liquid Exfoliant
Skin Perfecting 2% BHA Liquid Exfoliant
Paula's Choice · exfoliators
Solbar Fifty SPF 50
Solbar Fifty SPF 50
Person & Covey, Inc. · sunscreen
Heel Genius Moisturizing Foot Cream
Heel Genius Moisturizing Foot Cream
Soap & Glory · body-skincare
Natural Moisturizing Factors + HA
Natural Moisturizing Factors + HA
The Ordinary · moisturizer
AHA Cleansing Research Oil Cleansing Pore Clear
AHA Cleansing Research Oil Cleansing Pore Clear
BCL · makeup
Toleriane Purifying Foaming Face Cleanser
Toleriane Purifying Foaming Face Cleanser
La Roche-Posay · cleanser
Superfood Antioxidant Cleanser
Superfood Antioxidant Cleanser
Youth To The People · cleanser
Daily Essentials Refreshing Facial Wash Gel
Daily Essentials Refreshing Facial Wash Gel
Nivea · cleanser
Blush & Glow Strawberry Freshness Gel Face Wash With Strawberry Extracts
Blush & Glow Strawberry Freshness Gel Face Wash With Strawberry Extracts
Lakme · cleanser
Daily Essentials Mattifying Day Cream
Daily Essentials Mattifying Day Cream
Nivea · moisturizer
See all products with Sodium Hydroxide

References

Scientific sources

[1]

International Journal of Trichology, January-March 2015, pages 2-15

[2]

Journal of Cosmetic Dermatology, September 2010, Volume 9, Issue 3, pages 174-184

[3]

Acta dermato-venereologica, March 1995, pages 97-101

[4]
cosmeticsinfo.org/ingredient/sodium-hydroxide
[5]
cir-safety.org/sites/default/files/inorganic%20hydroxides.pdf
Semantic Analysis

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Frequently Asked Questions

Sodium Hydroxide — common questions

What is Sodium Hydroxide in skincare?

Sodium hydroxide, calcium hydroxide, magnesium hydroxide, and potassium hydroxide are white solids that can exist as powders. These compounds are utilized in a wide range of cosmetic and personal care products, including bath products, cleansers, fragrances, foot powders, hair dyes and colors, makeup, nail products, personal hygiene items, shampoos, shaving preparations, depilatories, skincare formulations, and sunless tanning products. Calcium and Sodium Hydroxide are also used in hair straight

What does Sodium Hydroxide do? / Functions of Sodium Hydroxide?

Common functions: BUFFERING, DENATURANT.

What is the comedogenic rating of Sodium Hydroxide? / Is Sodium Hydroxide comedogenic?

The comedogenic rating of Sodium Hydroxide has not been established in our database.

Does it clog pores?
No Rating Available

Whether Sodium Hydroxide clogs pores depends on the formulation and concentration.

Is Sodium Hydroxide safe for skin?
2 2/5 — Low risk

Sodium Hydroxide has a safety rating of 2 out of 5. A rating of 2 means it is generally considered safe for most skin types. Note: The Cosmetic Ingredient Review (CIR) Expert Panel has determined that sodium hydroxide is safe in cosmetics when used in formulations under proper manufacturing controls to ensure it is neutralized an

Is Sodium Hydroxide good for sensitive skin?
4 4/5 — High risk

Sodium Hydroxide has an irritancy rating of 4 out of 5. A rating of 4 means it has high irritation potential.

What are the side effects of Sodium Hydroxide in skincare?

Known considerations: The Cosmetic Ingredient Review (CIR) Expert Panel has determined that sodium hydroxide is safe in cosmetics when used in formulations under proper manufacturing controls to ensure it is neutralized and not present in the final product at a high pH. Additional risks: skin irritation (irritancy rating 4/5).

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