Sodium Hydroxide
Strong base that acts as a pH adjuster in cosmetics. Added in microdoses to bring the formula acidity to the required level.
Evidence by route
Topical application
In finished cosmetics it only works as a pH adjuster, not an active. After neutralizing acids it converts into a neutral salt.
How to read tiers A–F
- CWeak evidence. In vitro data, open-label studies, or expert consensus
Tolerability and safety
- Irritation potential
- Low
- Allergen risk
- Low
- Pregnancy
- Safe
- Suitable for
- Oily, Dry, Sensitive, Combination, Normal
About this ingredient
Sodium Hydroxide (NaOH, caustic soda) is a strong inorganic base. In cosmetics it functions only as a pH adjuster and neutralizer for acidic polymers (carbomer, acrylic copolymers). Concentration in the finished formula is a fraction of a percent. Mechanism. Raises pH to the target range (4.5-6 for most skincare), neutralizes polymer acid groups and converts them to gel form. Without NaOH or its analogues (TEA, AMP, tromethamine) a carbomer serum stays liquid and unstable. Where applied. Gels, serums, cleansers, creams. Often in sunscreens, acid toners (to correct working-solution pH), carbomer emulsions. On the label it appears near the bottom of almost any cream. Evidence base. Safety of a pH adjuster in cosmetics depends on final formula pH, not on NaOH itself. SCCS and CIR confirm safety up to 5% in cleansers and 2% in leave-on. Residual NaOH on skin is fully neutralized. Safety. Concentrated NaOH causes chemical burns, so only manufacturers handle it raw. In the finished product, after neutralization, it is safe and non-irritating. Pregnancy and lactation – safe in finished formulas. Not applied as a standalone agent.
Frequently asked questions
Is Sodium Hydroxide safe during pregnancy?
Sodium Hydroxide is considered safe during pregnancy at typical cosmetic concentrations. Systemic absorption through the skin is minimal.
What skin types is Sodium Hydroxide for?
Sodium Hydroxide suits: oily, dry, sensitive, combination, normal.
What is Sodium Hydroxide and what does it do in cosmetics?
Strong base that acts as a pH adjuster in cosmetics.
What's the INCI name for Sodium Hydroxide?
The INCI name is Sodium Hydroxide. It may also appear as: NaOH, Caustic Soda.
See Sodium Hydroxide in a product composition right on the store page
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