Background
Triheptanoin (CAS No. 620-67-7) is a synthetic triglyceride composed of three molecules of heptanoic acid esterified with glycerol. In cosmetic formulations, it has been used primarily as an emollient and solvent.
The regulatory clarification follows the approval of a pharmaceutical product containing Triheptanoin. On 23 March 2026, a Japanese company obtained manufacturing and marketing authorization under Article 14, Paragraph 1 of the PMDL for a medicinal product indicated for the treatment of long-chain fatty acid oxidation disorders (LC-FAOD). On the same date, the MHLW issued a Director-General notification designating Triheptanoin as a pharmaceutical general name.
Because companies had previously submitted applications and notifications for cosmetic products containing Triheptanoin, the Ministry considered it necessary to clarify how such products should be treated under the current regulatory framework.
Regulatory Position
Under Japan’s Standards for Cosmetics, substances classified as pharmaceutical ingredients are generally prohibited from use in cosmetic products unless specifically permitted. In its notice, the MHLW confirmed that Triheptanoin is now regarded as a pharmaceutical ingredient under the PMDL.
Consequently, products newly placed on the market as cosmetics are not expected to be accepted if they contain Triheptanoin. The Ministry’s position is based on the PMDL and the provisions of the Standards for Cosmetics that prohibit the use of pharmaceutical ingredients in cosmetic products.
Transitional Arrangements for Existing Products
The notice also addresses products that were developed and notified before the regulatory status of Triheptanoin changed.
According to the MHLW, some companies had already completed the necessary regulatory procedures for cosmetics containing Triheptanoin under the rules in force at the time. To avoid unnecessary disruption and protect legitimate business interests, the Ministry has established transitional arrangements for these products.
Cosmetics that completed the required filing or notification procedures before 20 April 2026, and whose formulations and labeling complied with the applicable requirements at that time, are permitted to continue being manufactured and marketed under these transitional arrangements. The new regulatory interpretation therefore does not affect products that had already achieved compliance prior to the issuance of the notice.
Implications for Industry
The Triheptanoin decision illustrates how changes in the regulatory status of an ingredient can affect cosmetic products in Japan. When a substance becomes classified as a pharmaceutical ingredient, its continued use in cosmetics may no longer be permitted under the Standards for Cosmetics, even if the ingredient had previously been accepted in cosmetic formulations.
Manufacturers marketing products in Japan should therefore monitor pharmaceutical approvals and related MHLW notifications closely. Regulatory reclassification of an ingredient can have significant implications for product compliance, reformulation strategies, and future market access.
Companies currently using Triheptanoin should review whether their products qualify for the transitional arrangements established by the notice and assess any implications for future product development.
