Sodium Hydroxide

SO-dee-um hy-DROX-ide

pH Adjuster 6/10 Safety Not CGControversial Synthetic Vegan

What Is Sodium Hydroxide?

A strong alkaline compound used as a pH adjuster in hair products and as the active ingredient in chemical hair relaxers. One of the most powerful bases used in cosmetics.

Source: Synthesized from sodium chloride (salt) electrolysis

Origin: Synthetic

Also known as: Lye, Caustic Soda, NaOH

What Does Sodium Hydroxide Do to Your Hair?

Adjusts pH in hair product formulations, typically used in tiny amounts to raise pH to optimal levels. In relaxers, it permanently breaks and reforms the disulfide bonds in hair keratin to straighten curly or coily hair.

Best For

Curly/coily hair wanting permanent straightening (in relaxers); all hair types (as pH adjuster)

Not Recommended For

All hair types at high concentrations, damaged hair, children (relaxers)

Concentration Matters

Trace amounts as pH adjuster; 1.5-2.5% in relaxers

Hair Type Compatibility

1A Straight Fine
1B Straight Medium
1C Straight Coarse
2A Wavy Fine
2B Wavy Medium
2C Wavy Coarse
3A Curly Loose
3B Curly Tight
3C Curly Corkscrew
4A Coily S-Shaped
4B Coily Z-Shaped
4C Coily Tight
Heat-damaged: Not recommended

Method Compatibility

Curly Girl (CG) Method: Avoid
CG Avoid

Safety & Regulation

6/10
AvoidCautionSafe

Extremely caustic at high concentrations. Chemical relaxers containing sodium hydroxide can cause severe scalp burns, hair breakage, and permanent damage if misused. As a pH adjuster at trace amounts in regular products, it is perfectly safe.

FDA Status: Generally Recognized As Safe

FDA permits use as pH adjuster in cosmetics. Relaxer use requires careful concentration control.

EWG Score: 5/10

HairAide Verdict

Completely safe as a pH adjuster at trace amounts in everyday products. As a relaxer ingredient, it demands professional application and caution. Do not confuse its use as a pH adjuster with its use in relaxers.

Products That Contain Sodium Hydroxide

Chemical relaxers, pH-adjusted shampoos/conditioners, keratin treatments

Alternatives to Sodium Hydroxide

If you want to avoid Sodium Hydroxide, look for products with these ingredients instead:

Potassium Hydroxide, Guanidine Hydroxide, Citric Acid

Frequently Asked Questions

Is Sodium Hydroxide safe for hair?

Sodium Hydroxide has a safety rating of 6/10. It's generally acceptable but may cause issues for some hair types. Extremely caustic at high concentrations. Chemical relaxers containing sodium hydroxide can cause severe scalp burns, hair breakage, and permanent damage if misused. As a pH adjuster at trace amounts in regular products, it is perfectly safe.

Is Sodium Hydroxide bad for curly hair?

Sodium Hydroxide is not CG-method approved. Curly hair types may want to avoid this ingredient or use products containing it sparingly.

Is Sodium Hydroxide CG-method approved?

No, Sodium Hydroxide is not approved for the Curly Girl method.

What can I use instead of Sodium Hydroxide?

Some alternatives to Sodium Hydroxide include: Potassium Hydroxide, Guanidine Hydroxide, Citric Acid

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