DIY Vitamin C Face Serum (Natural Recipe with Vitamin C Oil)

Learn how to make an oil-based DIY vitamin C face serum for glowing skin. This simple homemade skincare recipe is an easy-to-make, more stable alternative to water-based vitamin C serums (which often have short shelf lives). No preservative or refrigeration needed!

It’s no secret that Vitamin C (ascorbic acid) is essential for skin health. While oranges are better eaten than used on your face, a vitamin C serum is one of the next best options.

After all, this potent antioxidant is well-known for its ability to support collagen integrity, slow skin aging, as well as defend skin against blue light, UV damage, and pollution, to name just a few benefits_¹.

In theory, vitamin C face serums are also simple to make at home. But the problem is that they’re also notoriously delicate and prone to oxidizing, often turning orange or brown before you’ve had a chance to use them up.

And considering that this change of color, or oxidation, is a sign of the vitamin C no longer being viable, why would you want to waste your time and money on a useless DIY skin care product?

That’s why I made this simple, beginner-friendly oil serum formula. With only 3 main ingredients and a more stable form of vitamin C, this recipe avoids some of the common pitfalls of homemade vitamin C serums by resisting oxidation and spoilage.

Read on to learn how to reap the benefits of vitamin C in a simple, 3-ingredient DIY face serum for your natural skincare routine.

The problem with DIY vitamin C serums

Homemade vitamin C serums are often made with L-ascorbic acid (LAA), the main water-soluble form of vitamin C. Though well-studied and highly effective for scavenging and neutralizing free radicals², LAA degrades quickly when exposed to light, heat, and oxygen.

You’ll recognize spoiled vitamin C by its orange or brown color. This happens when ascorbic acid degrades into glycation products such as dehydroascorbic acid (DHA) and erythrulose³, one of the browning agents in self-tanners.

But since tanning agents such as erythrulose are now associated with skin aging⁴, it’s likely clear why you don’t want to use oxidized vitamin C on your skin!

All that aside, there are proven ways to make L-ascorbic acid serums more stable. Companies often formulate with added antioxidants such as ferulic acid, or they may opt for more stable forms of vitamin C such as magnesium ascorbyl phosphate or 3-glyceryl ascorbate.

But when it comes to DIYing your vitamin C, it’s much easier to make a facial oil over a water-based formula. Enter tetrahexyldecyl ascorbate (THDA or THD ascorbate), the oil-soluble, easy-to-use form of vitamin C we’ll be using in this serum recipe.

Vitamin C facial oil ingredients

This homemade antioxidant face serum requires only 3 main ingredients (and an optional 4th).

If you’re eager to get to the DIY, the ingredients and recipe can be found immediately below. But for those who are interested in further information on tetrahexyldecyl ascorbate, you can read more after the recipe.

Making this DIY serum is as simple as combining vitamin C and vitamin E with MCT oil. You’ll need:

• MCT oil (capric/caprylic triglycerides): Comprised of non-comedogenic saturated fatty acids, this lightweight, minimally greasy carrier oil won’t clog pores. It’s also PUFA free, so it’s devoid of unstable fatty acids that could oxidize the vitamin C. (Those familiar with Dr. Ray Peat’s work know it’s recommended to avoid PUFA and drink fresh orange juice for vitamin C – see more Ray Peat-inspired skincare recipes.)
• Tetrahexyldecyl ascorbate (vitamin C oil): This lipid-soluble vitamin C derivative converts to ascorbic acid in the skin², supporting skin health and supplying potent antioxidant protection. (More on this later)
• Vitamin E: When it comes to skincare, vitamin C works best in conjunction with Vitamin E, with whom it has a synergistic relationship⁵. Vitamin C regenerates vitamin E⁶, and vitamin E considerably lengthens vitamin C’s shelf life in skincare formulations⁷. As a bonus, these antioxidants also work together to prevent lipid peroxidation⁸ and mitigate UV damage6 (in other words, they protect your skin’s fatty acids).
• Annatto seeds (optional): If desired, you can also infuse your vitamin C face oil with annatto seeds (achiote). Annatto is rich in the carotenoids bixin and norbixin, which provide extra antioxidant stability (and a fun pop of orange peel color). Annatto has also been studied for its UV-protective, skin-reparative effects, making it a natural colorant with skin benefits⁹.

More skincare recipes with annatto:

More skincare recipes with tetrahexyldecyl ascorbate:

DIY Vitamin C Serum Recipe

26.7g MCT oil or capric/caprylic triglycerides (substitute squalane or fractionated coconut oil)
3g tetrahexydecyl ascorbate (vitamin C oil)
0.3g pure vitamin E oil
~1/8 tsp annatto seeds (optional)

Supplies + Equipment

Glass lab beaker for mixing
Cosmetic scale to measure ingredients
Dark glass dropper bottle for storage
Lab spatula or stirrer

How to make vitamin C serum at home

1. Measure oil. Pour MCT oil or carrier oil of choice into a clean glass lab beaker (or directly into your DIY serum bottle). Note: see instructions for annatto infused oil below.
   
2. Add vitamin C. Carefully weigh the correct amount of tetrahexyldecyl ascorbate into the carrier oil. Mix well to combine, or shake your bottle to disperse.
   
3. Add vitamin E. Add vitamin E oil to stabilize your formula and mix well to incorporate the viscous oil.
   
4. Transfer to bottle. Pour the finished product into a dropper bottle. It’s that simple – your vitamin C oil serum is ready to use.
   

Formula Notes

• This recipe yields a 1oz (30g) bottle of homemade vitamin C face serum.
• The formula contains 10% vitamin C, which is within the range for an effective vitamin C product¹⁰, and 1% vitamin E to increase THDA’s stability⁷.
• Keep your serum in a cool, dark place protected from light. Though clear glass bottles like the ones pictured are pretty, they are for display only, and dark amber glass is recommended to protect the fragile vitamin C.
• THDA combined with vitamin E is said to have a shelf life of 12 months⁷, so use your serum within that timeframe.
• As an optional step, you can infuse your serum with annatto seeds. Simply place your carrier oil into a small, heat-safe mason jar, add annatto seeds, and heat gently in a shallow water bath until the oil turns orange. Be very careful to seal the jar and do not allow any water to get inside. Once cool, strain out the seeds and use the annatto infused oil to make your face serum.
• Please note that annatto stains, so take caution with light colored clothing and bedding, and skip the annatto if you are at all concerned.

How to use your homemade face serum

To use your face serum, apply a few drops to clean skin during your morning or nighttime skincare routine to provide antioxidant protection, boost collagen, and support glowing skin.

Since this product’s consistency makes it more of a vitamin C facial oil or oil serum, it should be applied after lighter, water-based treatments or toners to seal in moisture. If using this serum in conjunction with a natural sunscreen, be sure to apply it under your SPF.

How often? The general consensus is that vitamin C skincare products can be safely used daily, as well as in conjunction with sunscreen, retinoids, other antioxidants and exfoliants such as glycolic acid⁵.

Vitamin C has also been shown to pair well with bakuchiol². (I love Bakuchiol Building Blocks, a potent treatment that also contains THD ascorbate.)

Finally, as always, you should do a patch test before using a new skincare product, and discontinue use if you experience any irritation. If you have particularly sensitive skin, you can also further dilute the serum with more MCT oil to make the vitamin C less potent.

Other uses: though this is a vitamin C serum for face, you can also use it on your body! Some enjoy vitamin C’s ability to even or brighten the skin tone and fade dark spots (not to be confused with lightening, which I am not condoning). Simply apply the vitamin C oil like you would any other moisturizing body oil.

Tetrahexyldecyl ascorbate for skin care

As mentioned, tetrahexyldecyl ascorbate (shortened to THD ascorbate or THDA) is a lipophilic form of vitamin C and precursor to ascorbic acid¹¹. Other names for tetrahexyldecyl ascorbate include vitamin C-isopalmityl tetraester (VC-IP), tetra-isopalmitoyl ascorbic acid (IPAA) and ascorbyl tetraisopalmitate (ATIP)¹².

THDA and other liposoluble vitamin C derivatives are often used in skincare products due to their high stability and beneficial effects on the skin⁷. With its silky, viscous texture and excellent moisturizing properties, THDA is easy to use and an excellent ingredient for oil-based skincare products.

I was first introduced to tetrahexyldecyl ascorbate in a product called Bakuchiol Building Blocks by The Sunscreen Company, a unique formula combining THDA, bakuchiol and oil-soluble salicylic acid for a powerhouse of skin-smoothing, antioxidant properties. So if you’re not inclined to DIY, you might also enjoy trying out a product with THDA.

More skincare products with tetrahexyldecyl ascorbate:

• Biossance Squalane + Vitamin C Rose Oil
• The Ordinary Ascorbyl Tetraisopalmitate Solution 20% In Vitamin F
• Paula’s Choice 25% Vitamin C + Glutathione Clinical Serum

Tetrahexyldecyl ascorbate benefits

Tetrahexyldecyl ascorbate’s benefits for skin include:

• Excellent absorption. THDA has the ability to penetrate the stratum corneum to deliver vitamin C below the epidermis¹³. It also penetrates the skin barrier 4 times better than magnesium ascorbyl phosphate, and delivers vitamin C to the skin 50 times better than ascorbic acid¹⁴.
• Increases collagen synthesis. THDA promotes collagen production and enhances the structural integrity of the skin. In other words, it helps slow down the normal process of skin aging².
• Sun protection. THD helps offer protection against sun damage, especially when combined with vitamin E. It defends against both UVA¹⁵ and UVB radiation, and has been shown to protect again UVB better than other types of vitamin C¹⁴.
• Antioxidant protection. Our skin is constantly exposed to an onslaught of oxidative stress from environmental factors, such as UV light, electronic devices, and air pollution. THD helps defend skin against these attacks by quenching free radicals and reducing oxidative stress².
• Improves sun damage. THD ascorbate has been clinically proven to improve sun damage and hyperpigmentation¹³. It also reduces melanin synthesis, which helps even out skin tone and lighten dark spots¹⁴.
• Reduces acne. Antioxidants such as THD may help reduce acne14 in some people, especially if the type of acne is caused by inflammation.

Note on THD ascorbate stability

While a multitude of studies have demonstrated THDA’s effectiveness and superior stability¹⁶, another study found that THDA was only effective for improving skin appearance when combined with another antioxidant (acetyl zingerone)¹¹.

One study isn’t conclusive, and it’s important to consider all sides of a topic. But, like all vitamin C derivatives, it does appear it’s best to combine THDA with other antioxidants for improved stability.

Acetyl zingerone is both water soluble and very expensive, so it wouldn’t work for an oil-based vitamin C serum. For this recipe, I opted to combine THD ascorbate with vitamin E and carotenoid-rich annatto.

As previously mentioned, not only do vitamin C and vitamin E stabilize one another, but vitamin E was specifically found to increase tetrahexyldecyl ascorbate’s shelf life in skincare formulas⁷. This combination of oil-soluble antioxidants helps provide extra insurance to stabilize the serum formula.

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