Everyone from your cousin to your bestie to your dermatologist has probably told you that you should be using a vitamin C serum. On top of that, if you took a look at the products on the shelf of your local pharmacy or beauty shop, you’d see plenty of bright and bolded mentions of vitamin C on their packaging. Vitamin C… it’s everywhere. And we can’t lie, it’s a pretty great ingredient.

The problem? Most vitamin C in skincare is L-ascorbic acid, which can cause skin irritation for some people—especially because products with L-ascorbic acid need to be formulated at a low pH, which doesn’t line up with your skin’s natural pH level.

It’s left enough people with sensitive skin wanting alternatives that our article on gentle vitamin C alternatives ended up being our most popular Mindful Beauty Magazine article last year.  

While we shared tons of great alternatives in that article, tetrahexyldecyl ascorbate is easily the closest sensitive-skin-friendly match to L-ascorbic acid. That’s because tetrahexyldecyl ascorbate (aka THD) is actually an L-ascorbic acid precursor (meaning it converts to L-ascorbic acid after it has already penetrated the skin), and is a stable vitamin C ester derivative. However, unlike L-ascorbic acid, THD is oil-soluble and therefore formulated at a higher pH, making it a better match for your skin’s natural pH levels.

THD is a better match for your skin’s natural pH levels than L-ascorbic acid.

We want to note that THD is at its best skin-benefits-wise when combined with acetyl zingerone to keep it from degrading. So while it is THD providing your skin with the benefits of vitamin C, the acetyl zingerone is still necessary to make sure the ingredient keeps its effectiveness. 

That’s why throughout this article, we’ll be talking about the benefits of THD, but please keep in mind we’re specifically talking about THD stabilized by acetyl zingerone.

Other names: Vitamin C, THD, THDC, THD-Ascorbate

What it is: brightening, smoothing, antioxidant, gentle, protective

You can find it in: our secret upcoming product launch 😉

What makes tetrahexyldecyl ascorbate such a great ingredient?

THD does all the great things a traditional vitamin C does: brightens, protects, and smooths the appearance of fine lines and wrinkles. While THD can degrade without acetyl zingerone, both in combination have been proven in studies to enhance collagen production and antioxidant effects¹. THD has also been shown to decrease signs of photodamage, such as skin wrinkling, and reduce hyperpigmentation².

Vitamin C in general (including both L-ascorbic acid and THD) is so well-loved because it’s a powerful antioxidant that helps protect the skin from oxidative stress, prevents collagen breakdown, reduces visible signs of aging, brightens dark spots, and evens out skin tone. We’ll break down each benefit further below!

THD Brightens and Improves the Appearance of Dark Spots and Uneven Skin Tone

THD, like L-ascorbic acid, is a tyrosinase inhibitor. But let’s talk about what that actually means, and how it relates to brightening skin and fading hyperpigmentation.

Tyrosinase is an enzyme found in melanocytes, your pigment-producing cells. When tyrosinase is oxidized, usually by UV damage, it causes melanin (aka anything from dark spots and hyperpigmentation to your tan and freckles) to form.

By inhibiting tyrosinase, THD can stop dark spots and hyperpigmentation from forming, and help fade any spots or unevenness that are already there. 

It sounds complicated, but the benefits are simple—an even skin tone, faded dark spots, and protection from future discoloration caused by sun damage.

THD Improves the Appearance of Fine Lines and Wrinkles

Speaking of sun damage, did you know it can cause collagen production in your skin to slow, which leads to slack skin, fine lines, and wrinkles? That’s why it’s a huge benefit that THD increases collagen production.

According to this study³, THD and acetyl zingerone together are able to increase the production of collagen proteins through influencing the fibroblasts in your skin (which are the cells that secrete collagen). 

All this technical talk means that THD improves the appearance of fine lines, wrinkles, and sun-damaged skin because it increases collagen production (something that naturally slows down as we age).

THD is Better for Sensitive Skin

If you have sensitive skin, there’s no 100% guarantee that THD won’t cause your skin to react. However, it’s much less likely to cause irritation or redness than L-ascorbic acid. So if you’ve tried a vitamin C serum in the past and your skin was not happy, THD might be your new holy grail ingredient (but, as we always recommend, do a patch test when trying a new product).

Why is THD better for sensitive skin? There are a few reasons. The first is one I mentioned before: THD has a pH of anywhere between 5 and 7, which allows it to be used in formulas that have a skin-neutral pH level. 

When your skin’s pH level is kept intact by using skincare that is not too acidic or basic for it, you’re protecting the integrity of your skin’s barrier, acid mantle, and microbiome, all defence mechanisms your skin has in place to protect it from outside damage.

If you’re curious about the role these three play in your skin (and how to choose skincare that protects them), we have an entire article dedicated to explaining why they’re important.

On the flip side, vitamin C products that use L-ascorbic acid as their vitamin C source need to be formulated at a lower pH level, meaning they are more acidic (and also more likely to irritate your skin)⁴.

THD Protects Against Skin Damage

THD protects the skin from free radical damage, which can damage your skin tissue and disrupt your skin’s natural functions. Why does that matter? Well, when your skin’s cells are damaged, it can show up visually on your face as unwanted skin texture, fine lines, hyperpigmentation, inflammation, redness, and more.

It’s THD’s oil-soluble nature that allows it to neutralize free radicals. That’s because much of the havoc free radicals wreak on your skin is targeted toward the oil-based components of your skin, such as lipids like ceramides and cholesterol. 

THD’s oil-soluble nature that allows it to neutralize free radicals.

THD’s protective abilities also extend to what other types of skincare products you can use with it. Often, derms and skincare experts will advise you not to mix your vitamin C serum with retinol. However, that only applies to L-ascorbic acid-based vitamin C formulas. THD is actually safe to use with your retinol products, as it doesn’t compound retinol’s photosensitivity side effects like L-ascorbic acid does.

Who is tetrahexyldecyl ascorbate good for?

THD is a great alternative for anyone who has tried L-ascorbic acid vitamin C and found their skin can’t tolerate it. This also includes people who can tolerate low percentages of L-ascorbic acid but can’t increase the amount without sensitivity.

It’s also great even if L-ascorbic acid doesn’t irritate you, as tetrahexyldecyl ascorbate penetrates deeper into the skin, and converts to L-ascorbic acid while already in the skin.

THD is also for anyone who wants the skin benefits of vitamin C, because even though it’s not the most common form of vitamin C in skincare, it has all the same incredible benefits. So, if you want brighter, firmer, more plump and radiant skin, THD is a great choice.

If you’re also wanting to address any hyperpigmentation, dark spots, fine lines, or wrinkles on your skin, THD can help improve their appearance while protecting your skin from further damage in the process.

Why THD over L-Ascorbic Acid?

THD is just as potent as L-ascorbic acid but more stable and less irritating to the skin. It doesn’t get much better than that! I shared most of this in the sections above, but here’s a recap:

Flexibility within your skincare routine: THD has more flexibility with what other products can be used with it. Experts advise not to use L-ascorbic acid vitamin C with retinol, AHAs/BHAs, or niacinamide, but using these with THD is fine.

Allows for pH-balanced formulation: THD is not as acidic pH-wise as L-ascorbic acid, allowing it to be used in formulas that have the same pH level as your skin. This keeps the formula from stripping the skin and compromising the skin barrier (as well as the acid mantle and microbiome).

Better absorption: THD is oil-soluble, which means it is easier for the skin to absorb than water-based L-ascorbic acid. Because THD is better at penetrating the skin, it’s also a more effective antioxidant⁵.

Summary

Tetrahexyldecyl Ascorbate:

• Is beneficial to the skin when stabilized by acetyl zingerone
• Is more potent and stable than its other vitamin C counterpart, L-ascorbic acid
• Is more suitable for sensitive skin than L-ascorbic acid
• Helps fade hyperpigmentation, dark spots, and uneven skin tone
• Increases collagen production
• Improves the look of fine lines and wrinkles
• Is pH-balanced and antioxidant–it protects against free radical damage while keeping the skin barrier intact
• Can be used with retinol, unlike L-ascorbic acid