A basic calcium salt of thioglycolic acid, used in depilatories and regulated in Annex III.
What it is
Calcium thioglycolate hydroxide is a calcium salt of thioglycolic acid (mercaptoacetic acid) in a 1:1 ratio, described in its chemical names as a trihydrate. CosIng lists it as a depilatory ingredient. In the EU it is covered by an entry in Annex III (substances subject to restrictions) that applies to thioglycolic acid and its salts, with mandatory label warnings.
Where it is used
Found in depilatory creams and other hair removal products.
Limits of interpretation
The INCI list shows which ingredients are present, not how much of each. Above 1%, ingredients are listed in descending order of weight; below 1% the order is free.
See the EU regulation section for the applicable limits, conditions and label warnings, which depend on the product type.
Functions
- Depilatory
- Breaking down the the mechanical strength of hair fibers so that they can be removed by mild scraping/rubbing.
EU regulation
- Product type
- (a) Hair products (b) Depilatories (c) Hair rinse-off products (d) Products intended for eyelash waving
- Maximum concentration
- (a) (i) 8% (ii) 11% (b) 5% (c) 2% (d) 11% The abovementioned percentages are calculated as thioglycollic acid
- Conditions and warnings
- Conditions of use: (a) (b) (c) (d) Avoid contact with eyes Rinse eyes immediately if product comes into contact with them. (a) (c) (d) Wear suitable gloves Warnings to be printed on the label: (a)(i) (b) (c) Contains thioglycolate Follow the instructions Keep out of reach of children (a)(ii) (d) For professional use only Contains thioglycolate Follow the instructions’
- As of
- 3 November 2026 · (EU) 2015/1190