What it is
The register’s chemical name for it: “Propanoic acid, 2-hydroxy-.”
- EU register name (INCI)
- LACTIC ACID
- CAS number
- 50-21-5
- EC number
- 200-018-0
What the register lists it for
These are the uses the European Commission’s CosIng register lists for Lactic Acid 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.”
- Humectant
-
Holds water in the product and on the surface it touches. Glycerin, honey and aloe are common humectants on curly-hair labels.
Register definition: “Retaining and/or preserving the moisture in a product during use.”
- Skin conditioning
-
The register’s broad role for ingredients that keep skin in good condition. On a hair label it often sits beside a hair role, or marks a plant oil or extract.
Register definition: “Maintaining the skin in good condition.”
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 1 label First five names: 0 of 1 Shampoos without it
- Clarifying shampoos 3 labels First five names: 0 of 3 Clarifying shampoos without it
- Rinse-out conditioners 1 label First five names: 0 of 1 Rinse-out conditioners without it
- Deep conditioners 3 labels First five names: 0 of 3 Deep conditioners without it
- Stylers 1 label First five names: 0 of 1 Stylers without it
- Heat protectants 2 labels First five names: 0 of 2 Heat protectants without it
- Curl refreshers 1 label First five names: 0 of 1 Curl refreshers without it
Every label, product by product (12)
- OLAPLEX Nº.4CURL Bond Shaper Hydrating Curl Shampoo Shampoo 36th of 62 names
- Bounce Curl Gentle Clarifying Shampoo Clarifying shampoo 15th of 31 names
- Camille Rose Clean Rinse Clarifying Shampoo Clarifying shampoo 17th of 34 names
- Cécred Clarifying Shampoo & Scalp Scrub Clarifying shampoo 28th of 31 names
- Bounce Curl Super Smooth Cream Conditioner Rinse-out conditioner 14th of 34 names
- tgin Honey Miracle Hair Mask Deep conditioner 10th of 29 names
- Bounce Curl Ayurvedic Deep Conditioner Deep conditioner 17th of 34 names
- Cantu Ultra Moisture Nourishing Mask Deep conditioner 16th of 26 names
- TRESemmé Bouncy Curls Defining Cream Styler 10th of 25 names
- Curlsmith Curlshield Cream Heat protectant 21st of 37 names
- TRESemmé Protecting Heat Styling Spray Heat protectant 17th of 29 names
- Curlsmith Shake & Shine Curl refresher 33rd of 51 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
- Sodium Hydroxide 25 labels
- Aminomethyl Propanol 15 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.