What is tetrahexyldecyl ascorbate in skincare?
Tetrahexyldecyl ascorbate – usually shortened to THD ascorbate or THDA – is an oil-soluble ester of vitamin C. Attaching fatty chains to ascorbic acid makes it lipophilic, so it dissolves in the oil phase of a formula rather than the water phase.
That solves two problems at once. It is far more stable than pure L-ascorbic acid, and being oil-soluble it penetrates the lipid-rich barrier more readily. It also works at skin-friendly pH, so it does not sting the way a low-pH vitamin C serum can.
What skin concerns does tetrahexyldecyl ascorbate treat?
Once converted to ascorbic acid in the skin it does what vitamin C does: neutralises free radicals, inhibits tyrosinase to fade pigment, and supports collagen synthesis for firmness and fine lines.
It is a good fit for dry and sensitive skin that cannot tolerate L-ascorbic acid. One caveat from the stability literature is that THDA degrades quickly under some conditions despite its reputation, so packaging and formulation still matter.
What ingredients are best paired with tetrahexyldecyl ascorbate?
Vitamin E and ferulic acid support it as they do any vitamin C, and because it is oil-soluble it sits naturally alongside squalane, ceramides and facial oils.
It layers comfortably with niacinamide, peptides and retinoids, and it is gentle enough to use morning and night. As with all ascorbic acid derivatives, results depend on conversion in the skin, so give it three months before judging. Take our Skin Quiz.
What are clogged pores?
A clogged pore is a hair follicle blocked by a mix of sebum, dead skin cells and debris. Left open to the air the plug oxidises and darkens into a blackhead; sealed over by skin it becomes a whitehead or closed comedone.
Clogged pores are the starting point of nearly all acne – the microcomedone forms first, and inflammation follows only if bacteria and immune response get involved.
What causes clogged pores?
Excess sebum and abnormal keratinisation are the two mechanics. When the follicle lining sheds cells faster than they can clear, they bind with oil and form a plug.
Comedogenic products (heavy oils, some silicones and waxes), thick makeup worn for long stretches, humidity, sweat left on the skin, hormonal shifts and insufficient cleansing all contribute. So does over-cleansing, which damages the barrier and drives oil production up.
What ingredients are best for clogged pores?
Salicylic acid is the first choice because it is oil-soluble and works inside the pore rather than just on the surface. Glycolic and lactic acid clear the surface layer, and clay masks absorb excess oil weekly.
Retinoids are the most effective long-term fix, because they change how the follicle sheds in the first place. Add niacinamide to regulate sebum and keep the barrier intact, and switch to non-comedogenic, lightweight hydrators. Take our Skin Quiz to find products that will not re-clog you.
