What it is
- EU register name (INCI)
- SODIUM HYDROXIDE
- CAS number
- 1310-73-2
- EC number
- 215-185-5
What the register lists it for
These are the uses the European Commission’s CosIng register lists for Sodium Hydroxide in any cosmetic, hair roles first. They say why a maker might add it, not what it does in one formula, and they aren’t a safety rating.
- Buffering
-
Keeps the product’s pH (how acidic it is) steady.
Register definition: “Stabilising the pH of an aqueous medium in a narrow range even if an acid or base is added. Altering and/or maintaining a cosmetic product's pH at the desired level.”
- Denaturant
-
Makes alcohol taste too bad to drink. It is why labels say Alcohol Denat.
Register definition: “Rendering cosmetics unpalatable. Mostly added to cosmetics containing ethyl alcohol to make it unsuitable for ingestion.”
Where it sits on each label
US labels list ingredients from most to least, except that those at 1% or less may follow in any order. A name near the top is a large part of the formula. A label doesn’t mark where the 1% point falls, so further down, the order says little about how much is in it.
- Shampoos 5 labels First five names: 0 of 5 Shampoos without it
- Clarifying shampoos 5 labels First five names: 0 of 5 Clarifying shampoos without it
- Rinse-out conditioners 4 labels First five names: 0 of 4 Rinse-out conditioners without it
- Deep conditioners 3 labels First five names: 0 of 3 Deep conditioners without it
- Leave-in conditioners 4 labels First five names: 0 of 4 Leave-in conditioners without it
- Stylers 1 label First five names: 0 of 1 Stylers without it
- Protein treatments 1 label First five names: 0 of 1 Protein treatments without it
- Heat protectants 2 labels First five names: 0 of 2 Heat protectants without it
Every label, product by product (25)
- Cantu Ultra Moisture Nourishing Shampoo Shampoo 24th of 31 names
- Kristin Ess Moisture Rich Curl Shampoo Shampoo 35th of 41 names
- OLAPLEX No.4 Bond Maintenance Strengthening Shampoo Shampoo 67th of 78 names
- PATTERN Hydration Shampoo Shampoo 38th of 42 names
- OLAPLEX Nº.4CURL Bond Shaper Hydrating Curl Shampoo Shampoo 58th of 62 names
- Cécred Clarifying Shampoo & Scalp Scrub Clarifying shampoo 23rd of 31 names
- Curlsmith Curl Reset Detox Shampoo Clarifying shampoo 21st of 27 names
- Cécred Detoxifying Shampoo Clarifying shampoo 31st of 38 names
- Camille Rose Clean Rinse Clarifying Shampoo Clarifying shampoo 31st of 34 names
- Maui Moisture Scalp Care Clarifying Shampoo with Apple Cider Vinegar Clarifying shampoo 32nd of 34 names
- Curlsmith Essential Moisture Conditioner Rinse-out conditioner 23rd of 33 names
- DevaCurl One Condition Original Rinse-out conditioner 17th of 22 names
- Curlsmith Fragrance-Free Conditioner Rinse-out conditioner 23rd of 29 names
- Kristin Ess Moisture Rich Curl Conditioner Rinse-out conditioner 38th of 41 names
- tgin Honey Miracle Hair Mask Deep conditioner 19th of 29 names
- Curlsmith Double Cream Deep Quencher Deep conditioner 30th of 36 names
- Briogeo Don’t Despair, Repair! Deep Conditioning Mask Deep conditioner 38th of 40 names
- Curlsmith Weightless Air Dry Cream Leave-in conditioner 22nd of 33 names
- tgin Green Tea Super Moist Leave-In Conditioner Leave-in conditioner 25th of 34 names
- SheaMoisture Coconut & Hibiscus Hold & Shine Moisture Mist Leave-in conditioner 20th of 25 names
- Curlsmith Fragrance-Free Leave-In Leave-in conditioner 22nd of 25 names
- Not Your Mother's Curl Talk Fragrance & Protein Free Sculpting Gel Styler 12th of 12 names
- ApHogee Keratin 2 Minute Reconstructor Protein treatment 22nd of 44 names
- Curlsmith Miracle Shield Heat protectant 24th of 34 names
- OLAPLEX Nº.9 Bond Protector Nourishing Hair Serum Heat protectant 22nd of 31 names
Each line runs from the first name on a label to the last; a dot is where this ingredient sits. Makers change formulas now and then; if the list on your bottle differs, go by your bottle.
Your next step
Other buffering ingredients on these labels
- Citric Acid 93 labels
- Aminomethyl Propanol 15 labels
- Lactic Acid 12 labels
- Acetic Acid 7 labels
- Sodium Acetate 7 labels
- Disodium Phosphate 6 labels
- Sodium Lactate 5 labels
- Sodium Phosphate 5 labels
Updated · The name, numbers and uses come from the European Commission’s CosIng entry (CC BY 4.0); we write the uses in US spelling and put the hair ones first. The labels are each maker’s own. The order rule is the FDA’s Cosmetics Labeling Guide. All our sources are on the Sources page.