Triheptanoin
No meaningful concern for most people; irritation is possible but rare.
Also written as: Glyceryl Triheptanoate
What it is
Triheptanoin is glycerin joined to three molecules of heptanoic acid, an odd-chain seven-carbon fatty acid. Because odd-chain fatty acids are rare in nature, it is made synthetically to a fixed specification, which means no batch variation, no colour and no smell. In cosmetics it behaves like an even lighter version of caprylic/capric triglyceride, and it also has a separate life as a licensed oral medicine for rare metabolic disorders.
What it does well
Extremely light, consistent and odourless emollient
Its short, uniform fatty acid chains give a very low viscosity and a dry finish, useful in products that need to feel weightless. Being fully synthetic, it avoids the batch-to-batch variation and oxidation problems of pressed plant oils.
Moderate evidence
Worth knowing
No topical benefit beyond emolliency
Triheptanoin is a texture ingredient. Its approval as an oral drug for long-chain fatty acid oxidation disorders shows the molecule is well characterised, but tells you nothing about what it does on skin.
Matters most toAnyone reading a marketing claim that implies medical pedigree.
Where the EU stands
No specific restriction
Not listed in any Annex of the EU Cosmetics Regulation, so there is no specific concentration limit; it is still covered by the general safety assessment every cosmetic product must pass before sale.
