Thioglycolic Acid (치오글리콜산): Korea’s Sole Notified Depilatory Cosmetic Ingredient

Thioglycolic acid (Korean: 치오글리콜산 in the functional-cosmetics appendices, 치오글라이콜릭애씨드 in the safety-standards appendix and in the KCIA ingredient dictionary) occupies an unusual position in Korean cosmetic regulation. Appendix 4 of the Regulation on Functional Cosmetics Review lists the notified ingredients and amounts for each functional category. Item 5 of that appendix — the category for removing body hair — contains exactly one ingredient, and this is it. Closing the ingredient closes the category.

That is not the only thing that makes the record unusual. For most notified functional ingredients the regulation fixes an amount and a set of dosage forms, and the efficacy wording follows from the category. Here the regulation goes further: it fixes the efficacy phrase itself as “제모(체모의 제거)”, fixes the four permitted dosage forms, fixes the directions-for-use text down to the waiting time and the instruction not to rub, and adds a pH window. Appendix 4 has six items in total, and this is the only one carrying a condition beyond the amount.

The second register matters as much as the first. Under Appendix 2 of the Cosmetic Safety Standards, thioglycolic acid together with its salts and esters is a restricted raw material whose entry sets ceilings by use — permanent waving and hair straightening taken together, depilatory products, hair dyes, and rinse-off hair products — with narrower conditions attached to certain two-bath permanent-waving and hair-straightening preparations, and a remark that closes everything else: prohibited in other products. The depilatory ceiling there is 5%, and the functional range in Appendix 4, 3.0–4.5%, sits inside it. The two appendices do not conflict; they are stacked, and reading only one of them produces a partial record.

Ingredient Snapshot

Chemical identity is taken from PubChem. Standardized naming, ingredient code, and compounding purposes are taken from the KCIA ingredient dictionary. The functional listing, amount, dosage forms, efficacy wording, and pH condition are taken from the Regulation on Functional Cosmetics Review; the raw-material and preparation monographs from the Standards and Test Methods; the use ceilings and prohibition from the Cosmetic Safety Standards.

Regulatory Records

Why “80%” Is Not a Concentration

The listing name in Appendix 4 is “치오글리콜산 80%”, and the figure in the amount column is “3.0–4.5% as thioglycolic acid”. These two percentages are measured on different things and cannot be compared. The 80% is a raw-material grade: Appendix 7 monographs an 80% preparation and assays it at 78.0–82.0% thioglycolic acid, which is what makes it that grade. The 3.0–4.5% is the concentration of the compound in the finished cosmetic. The two figures are measured on different bases and are not interchangeable. Recording the 80% raw-material grade as an in-product concentration would misstate the regulatory record, and the figure would exceed the Appendix 2 ceiling for depilatory products.

This is the same class of error that unit mismatches produce elsewhere in ingredient writing, and it is built into the listing name here rather than arising from a later misreading. The appendices themselves keep the two apart — a material grade in the monograph, a compound concentration in the amount column — and this page follows that separation.

Two pH Ceilings Written With Different Inequalities

Appendix 4 item 5 states that the pH range must be 7.0 or above and below 12.7. Appendix 2 states, for lithium hydroxide, calcium hydroxide, and potassium or sodium hydroxide used to adjust pH in depilatory products, that the final product pH must be 12.7 or below. The numeral is the same and the inequality is not. The two conditions sit in different notifications, attach to different subjects — one to the functional product, the other to the alkali used in it — and this page records them separately rather than merging them into a single range.

Naming Across Three Layers

The Appendix 4 and Appendix 7 listing name is 치오글리콜산. The Appendix 2 and KCIA name is 치오글라이콜릭애씨드. Searching the KCIA dictionary for 치오글리콜산 returns nothing. That mismatch would ordinarily be an open question, and in this project it has held other ingredients back. It does not hold this record back, and the reason is worth stating precisely, because each source carries a different part of the chain. Appendix 7 directly links 치오글리콜산 with Thioglycolic Acid, Mercaptoacetic acid, 티오글리콜산, and C2H4O2S : 92.12, all printed in one monograph heading; it carries no CAS number and does not use the name 치오글라이콜릭애씨드. Separately, KCIA code 2844 links 치오글라이콜릭애씨드 with Thioglycolic Acid, CAS 68-11-1, EC 200-677-4, and C2H4O2S; Appendix 2 also associates 치오글라이콜릭애씨드 with CAS 68-11-1; and PubChem CID 1133 confirms the chemical identity behind that CAS, with the same molecular formula and weight. The equivalence of the two Korean listing names is therefore established by cross-referencing shared identifiers across these sources, not by a single regulatory text stating the equivalence in one line.

Notification-Number Note

The standalone appendix extracts circulating for Appendix 4 do not carry a notification number or effective date. The numbers on this page come from the full notified texts, which print them: 제2025-88호 and 제2025-89호, both dated 2025-12-16, and 제2026-19호 dated 2026-03-18. The revision history printed at the front of the Review Regulation also lists 제2023-61호 (2023-09-21), which is a superseded edition and not the current one.

Claim Safety Matrix

The classifications below are the claim-handling categories recorded in this database — Allowed, Caution, Avoid, and Prohibited. They describe how wording is treated in this record and require human review; they are not legal determinations issued by MFDS, and they do not by themselves settle the lawfulness of a particular label, advertisement, news report, or academic discussion.

The Allowed entry below is unusual in that the notification fixes the wording itself. Where other notified categories set an amount and leave the phrasing to follow the category, Appendix 4 item 5 states the efficacy phrase verbatim and restricts the directions-for-use text as well. Rewriting the phrase does not merely risk overstatement; it leaves the wording the notification authorized.

The Prohibited entry rests on a positive regulatory instrument located in this record — an explicit remark in Appendix 2 closing all uses outside those it lists — rather than on the absence of a registration. Note the two different objects involved: Appendix 2 prohibits the use of the raw material itself, while the grade in this table records how wording asserting or implying such use is handled in this database.

Evidence Boundaries: What This Page Does Not Claim

The following claims are outside the scope of this ingredient record:

Treatment or prevention of any disease. Thioglycolic acid is recorded here as a notified cosmetic ingredient and a restricted cosmetic raw material. Nothing on this page states or implies that it treats, prevents, or alleviates any condition. Excessive hair growth has medical causes in some people; this record does not address them and the notified wording does not reach them.

Pharmaceutical or quasi-drug status by implication. Whether depilatory products in Korea exist in any register other than functional cosmetics was not established within the scope of this record. The regulation body cites Article 2 subparagraph 7 of the Enforcement Rule of the Cosmetics Act in connection with thioglycolic acid, and that provision was not read for this page. Adjacent registers are therefore neither asserted nor ruled out here.

Safety in use, tolerability, or suitability for any person. The appendices set composition limits, a pH window, purity tests, and assay methods. Those are product-composition and quality standards. They are not a statement that a compliant product is suitable for a given individual, for a given body area, or alongside other products, and this page does not convert them into one.

Individual outcomes. Nothing here predicts what any particular person will experience, how much hair will be removed, or for how long. The notified amount range and the directions-for-use text are regulatory conditions on the product, not personal guidance.

Product-level guarantees or comparisons between depilatory methods. This page does not evaluate specific products and does not rank chemical depilation against shaving, waxing, or light-based methods on effectiveness, comfort, or duration. The sources used here make no such comparison, and this record does not supply one.

The salts and esters as separate entities. Appendix 2 groups thioglycolic acid with its salts and esters under one entry, while KCIA registers ammonium, ethanolamine, calcium, sodium, potassium, magnesium, cysteamine and other thioglycolates under their own ingredient codes. This record covers the acid, which is what Appendix 4 item 5 names. Whether the salts and esters warrant separate entity records has not been decided here.

Dosage-form asymmetry. Appendix 4 permits four dosage forms while Appendix 7 monographs only the cream. That asymmetry is recorded above as observed. Its regulatory meaning was not established within the scope of this record and is not interpreted.

Currency beyond the verification date

Korean cosmetic notifications are amended periodically. The notification numbers, appendix contents, and line-level locations on this page reflect verification against the full notified texts as of 2026-09-02. Later amendments may change the applicable record, and the appendix extracts that circulate separately do not carry notification numbers by which currency can be checked.

Related Entities

Related Ingredients

• Salicylic Acid — the ingredient in Appendix 4 item 6, the acne-prone-skin category. Like item 5, that item lists a single ingredient, and its record shows the same structure of a notified amount paired with restrictions elsewhere
• Hydroquinone — listed in Appendix 1 of the Cosmetic Safety Standards as a raw material that may not be used in cosmetics. Useful as the contrasting case: Appendix 1 closes an ingredient entirely, while Appendix 2 permits it within stated ceilings
• Niacinamide, Arbutin — notified ingredients in Appendix 4 item 2, the skin-brightening category, where the item lists nine ingredients rather than one
• Ammonium thioglycolate, ethanolamine thioglycolate, calcium thioglycolate, sodium thioglycolate, potassium thioglycolate, magnesium thioglycolate, cysteamine thioglycolate — the salts and esters grouped with the acid in Appendix 2, each holding a separate KCIA ingredient code. Not covered by this record
• Lithium hydroxide, calcium hydroxide, potassium hydroxide, sodium hydroxide — alkalis whose Appendix 2 entries carry the depilatory pH condition

Related Product Types

• Depilatory cream, lotion, solution, aerosol (functional cosmetics under Appendix 4 item 5)
• Permanent waving preparations and hair straighteners (restricted use under Appendix 2 — 11% jointly, with a narrower figure for heat-assisted two-bath straighteners and a separate figure for exothermic two-bath permanent waving)
• Hair dyes; rinse-off hair products (restricted use under Appendix 2, different ceilings)

Related Claims

• 제모(체모의 제거) — the notified efficacy phrase, fixed verbatim by Appendix 4 item 5
• Permanence and regrowth wording — outside the notified phrase, and contrary to the item’s own repeat-application directions
• Use outside the product categories listed in Appendix 2 — closed by the remark column

Related Regulatory Concepts

• Notified functional cosmetic ingredient (고시원료) — an ingredient listed in Appendix 4, for which supporting data submission is waived
• Functional cosmetic monograph (각조) — raw-material and preparation standards in the Standards and Test Methods notification
• Restricted cosmetic raw material (사용상의 제한이 필요한 원료) — Appendix 2 of the Cosmetic Safety Standards
• Prohibited cosmetic raw material (사용할 수 없는 원료) — Appendix 1, where this ingredient does not appear
• Raw-material grade versus in-product concentration — two percentages on different bases

Source Transparency Note

This page uses the following source classification:

Naming-layer and identity-layer sources are not used as functional-claim evidence. KCIA establishes what this ingredient is called and under which compounding purposes it is registered; the dictionary states on its own page that inclusion does not establish that a material may be used in cosmetics, and this record treats it accordingly. PubChem establishes chemical identity and nothing about Korean status. All efficacy wording on this page traces to the Regulation on Functional Cosmetics Review, all quality standards to the Standards and Test Methods, and all use limits and prohibitions to the Cosmetic Safety Standards.

Frequently Asked Questions

Is thioglycolic acid a regulated ingredient in Korea?
Yes, in two registers at once. Thioglycolic acid (치오글리콜산 / 치오글라이콜릭애씨드) is the single notified ingredient in Appendix 4 item 5 of the Regulation on Functional Cosmetics Review, MFDS notification 제2025-88호, for products that remove body hair, at 3.0–4.5%. It is separately listed in Appendix 2 of the Cosmetic Safety Standards, notification 제2026-19호, as a restricted raw material together with its salts and esters, with ceilings set by use across five product categories, narrower conditions for certain two-bath preparations, and a prohibition on use in other products. It does not appear in Appendix 1, the list of raw materials that may not be used in cosmetics.

What claims are allowed for thioglycolic acid in Korean cosmetics?
One, and the notification writes it out: “제모(체모의 제거)”. Appendix 4 item 5 fixes the efficacy statement rather than leaving it to be phrased from the category, and it also fixes the permitted dosage forms — solution, cream, lotion, aerosol — and the directions-for-use text. The phrase is available to a product meeting those conditions, at 3.0–4.5% thioglycolic acid, with final pH at or above 7.0 and below 12.7. Rewriting the phrase moves outside the wording the notification authorized.

Why does the ingredient name say 80% when the permitted amount is 3.0 to 4.5%?
Because the two percentages measure different things. “치오글리콜산 80%” is a raw-material grade, and Appendix 7 of the Standards and Test Methods monographs it as an 80% preparation assayed at 78.0–82.0% thioglycolic acid. The 3.0–4.5% in Appendix 4 is the concentration of thioglycolic acid in the finished cosmetic. The grade describes the material a manufacturer buys; the amount describes what ends up in the product. The two are measured on different bases and are not interchangeable. Recording the 80% raw-material grade as an in-product concentration would misstate the regulatory record, and the figure would exceed the Appendix 2 ceiling for depilatory products.

Can a depilatory product say the hair will not grow back?
Not on the basis of this notification. The authorized efficacy phrase for thioglycolic acid is about removal, and neither Appendix 4 nor Appendix 7 says anything about hair roots, regrowth, or how long an effect lasts. The item’s own directions-for-use text anticipates repetition, noting that on short coarse hair in shaved areas it is advisable to use the product more than once, at intervals of several days. Permanence wording is recorded here as Avoid because it contradicts the text it would be citing.

Why does thioglycolic acid have different limits for different products?
Because Appendix 2 sets ceilings by use, not by ingredient alone. The entry covering thioglycolic acid, its salts and esters carries four bulleted limits, each expressed as thioglycolic acid: 11% for permanent waving and hair straightening taken together, and inside that entry 5% for heat-assisted two-bath hair straighteners and an amount corresponding to 19% for exothermic two-bath permanent waving preparations; 5% for depilatory products; 1% for hair dyes; and 2% for rinse-off hair products. The remark column then closes everything else: use in other products is prohibited. A ceiling from one use does not carry to another, and the depilatory figure — 5% — is the one that contains the Appendix 4 functional range of 3.0–4.5%.

Is thioglycolic acid the same substance as 치오글라이콜릭애씨드?
Yes, but it is worth being precise about how that is established, because no single document states it. Appendix 7 directly links 치오글리콜산 with Thioglycolic Acid, Mercaptoacetic acid, 티오글리콜산, and C2H4O2S : 92.12 in one monograph heading; it carries no CAS number and does not use the name 치오글라이콜릭애씨드. Separately, KCIA code 2844 links 치오글라이콜릭애씨드 with Thioglycolic Acid, CAS 68-11-1, EC 200-677-4, and C2H4O2S; Appendix 2 also associates 치오글라이콜릭애씨드 with CAS 68-11-1; and PubChem CID 1133 confirms the chemical identity behind that CAS. The equivalence of the two Korean listing names is therefore established by cross-referencing shared identifiers across these sources rather than by a single regulatory text stating it in one line.