Paula's Choice Resist Super Antioxidant Serum Versus ZO Skin Health 10% Vitamin C Self-Activating

Paula's Choice Resist Super Antioxidant Serum Versus ZO Skin Health 10% Vitamin C Self-Activating

This anti-aging serum is formulated around Tetrahexyldecyl Ascorbate and Palmitoyl Tripeptide-5 to soften the look of wrinkles and brighten dull-looking skin.

This brightening serum is formulated around Ascorbic Acid and Tetrahexyldecyl Ascorbate to brighten dull-looking skin and fade the look of dark spots.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Cyclopentasiloxane

Dimethicone

Tetrahexyldecyl Ascorbate

Palmitoyl Tripeptide-5

Ceramide NP

Tocotrienols

Tocopherol

Ubiquinone

Thioctic Acid

Tocopheryl Acetate

Magnesium Ascorbyl Phosphate

Ferulic Acid

Beta-Glucan

Superoxide Dismutase

Epigallocatechin Gallate

Ergothioneine

Glutathione

Xanthophylls

Glycine Soja Seed Extract

Glycerin

Arctostaphylos Uva Ursi Leaf Extract

Lupinus Albus Seed Extract

Curcuma Longa Root

Elaeis Guineensis Oil

Phenoxyethanol

Cyclopentasiloxane, Dimethicone, Tetrahexyldecyl Ascorbate, Palmitoyl Tripeptide-5, Ceramide NP, Tocotrienols, Tocopherol, Ubiquinone, Thioctic Acid, Tocopheryl Acetate, Magnesium Ascorbyl Phosphate, Ferulic Acid, Beta-Glucan, Superoxide Dismutase, Epigallocatechin Gallate, Ergothioneine, Glutathione, Xanthophylls, Glycine Soja Seed Extract, Glycerin, Arctostaphylos Uva Ursi Leaf Extract, Lupinus Albus Seed Extract, Curcuma Longa Root, Elaeis Guineensis Oil, Phenoxyethanol

Dimethicone Crosspolymer

Ascorbic Acid

Citrus Aurantium Amara Peel Oil

Squalane

Limonene

Citral

Cyclopentasiloxane, Dimethicone Crosspolymer, Ascorbic Acid, Dimethicone, Citrus Aurantium Amara Peel Oil, Squalane, Tetrahexyldecyl Ascorbate, Tocopheryl Acetate, Ubiquinone, Limonene, Citral, Phenoxyethanol

Reviews

Be the first to review

Alternatives

Ingredients Explained

These ingredients are found in both products.

Ingredients higher up in an ingredient list are typically present in a larger amount.

Cyclopentasiloxane (D5) is a lightweight silicone that mostly acts as an emollient and solvent in cosmetics. Its the reason your products feel silky, fast-spreading, and non-greasy.

Since D5 is volatile, it does its thing and then evaporates off the skin quickly.

The safety profile of this ingredient is reassuring; the US CIR Expert Panel concluded D5 is safe as used in cosmetics and Health Canada concluded that D5 is not harmful to human health or the environment as currently used in cosmetics

There's a study that people mention about D5 in a rat study showing tumors. This study is related to long-term inhalation of high D5 levels.

Regulatory bodies have judged this study to be not applicable in topical skincare since skin absorption of D5 is very low and we're not really inhaling huge amounts of D5.

The only restriction for this ingredient is environmental. The European Chemicals Agency (ECHA) restricted D5 in wash-off cosmetics at or above 0.1% due to their persistence in water.

Dimethicone is a type of synthetic silicone created from natural materials such as quartz. It is also known as polydimethylsiloxane.

What it does:

Dimethicone comes in different viscosities:

Depending on the viscosity, dimethicone has different properties.

Ingredients lists don't always show which type is used, so we recommend reaching out to the brand if you have questions about the viscosity.

This ingredient is unlikely to cause irritation because it does not get absorbed into skin. However, people with silicone allergies should be careful about using this ingredient.

Note: Dimethicone may contribute to pilling. This is because it is not oil or water soluble, so pilling may occur when layered with products. When mixed with heavy oils in a formula, the outcome is also quite greasy.

Phenoxyethanol is one of the most widely used preservatives in skincare (and for good reason!).

It has a large spectrum of antimicrobial activity and especially effective bacteria, yeast, and mold while only having a weak effect on your skin's natural microbiome.

On a cellular level, it disrupts the cell membranes of microbes by poking holes that make the cell leak. This shuts down the chemical reactions the microbe needs to make energy so it can no longer survive.

Another perk of this ingredient is that it stays functional across a wide pH range (3-10).

You'll often see it paired with boosters like Ethylhexylglycerin; one study showed that a 1:9 ratio of Ethylhexylglycerin to Phenoxyethanol damages bacterial membranes as effectively as doubling the Phenoxyethanol concentration on its own.

Typical use concentrations range from 0.3-1% depending on the formula, and this ingredient is capped at 1% int the EU.

Safety-wise, the fear mongering does not hold up to the evidence. The EU's Scientific Committee on Consumer Safety and FDA consider it safe as a preservative at up to 1%, including for children of all ages.

Adverse systemic effects only showed up in animal studies at exposures roughly 200x higher than what people get from cosmetics. And despite its very widespread use, this ingredient is a rare sensitizer and allergic reactions are uncommon.

Tetrahexyldecyl Ascorbate (THD) is a stable and oil-soluble form of Vitamin C.

THD is special in that it has the ability to travel deeper into skin than traditional ascorbic acid while maintaining the same skin benefits (double win!).

Because it’s oil-soluble, THD dives deep into your skin’s fatty layers (think ceramides and cholesterol) to fight off the kind of free radicals that mess with your skin barrier. This makes it a great pair with water-based vitamin C (ascorbic acid) that mainly works on the surface.

Even at just 0.1%, THD is already showing great antioxidant activity. When used up to 2%, it helps keep your skin happy and calm, especially when it’s stressed from pollution or sun.

Want to fade dark spots or tackle hyperpigmentation? You’ll want 5% or more. Pairing it with brightening buddies like niacinamide or licorice root gives even better results. One study even used 30% THD with other brighteners and saw real results on stubborn discoloration, even in melasma-prone skin.

A note on THD: It’s has a slightly silky, oily texture and usually shows up colorless or pale yellow (though the exact shade can vary by supplier).

While you can sneak it into water-based formulas, it really shines when paired with silicones or oils, which help your skin soak it up better.

THD is pretty stable, but it’s still vulnerable to degradation like ascorbic acid. Too much light or heat (above 113°F / 45°C) can break it down over time. Go for dark and opaque packaging that keeps it safe and shady!

Read more about other types of Vitamin C:

Tocopheryl Acetate is a stable, shelf-friendly form of vitamin E.

Formulators love it because plain vitamin E oxidizes quickly once it hits air. This acetate version stays stable and resists going off, helping to extend a product's shelf life.

It's actually inactive on its own and works like a slow-release "storage" form; the enzymes in your skin called esterases gradually convert it into active vitamin E over time.

One in vivo study showed 5% of the acetate in the living layer of the epidermis converted to vitamin E after 5 days of application. This study also found the skin gained protection against UV damage even though the conversion was slow and small.

Once converted, vitamin E acts as a skin's main fat-soluble antioxidant that fights free radicals to protect skin from damage.

Topical vitamin E generally boosts the skin's photoprotection, and it reduced UV-damage in animal models.

This ingredient has some brightening potential but it's more of a prevention ingredient than spot-fader. Cell studies show it can slow down melanin production but it's worth noting that it's not the most powerful brightener out there.

Overall, it has a pretty solid safety profile and has been found to be non-irritating and non-comedogenic. Allergic reactions may happen but stay rare due to how widely the ingredient gets used.

The concentration will vary depending on the formula; industry data shows 0.1% in baby lotions, 3% in lipsticks, and 5% in foot powders. You can also find this ingredient at 100% in a pure vitamin E oil.

Most leave-on skincare keeps it at the lower end, often between 0.5-1%.

Ubiquinone (Coenzyme Q10) is a molecule already found in our bodies. It is a potent antioxidant and skin-soothing ingredient.

Aging and environmental exposure diminishes our skin's natural ubiquinone levels. This is much like our natural collagen and elastin.

The good news is: studies show applying this ingredient topically replenishes ubiquinone levels in our skin. This also comes with a ton of skin benefits. These benefits include:

Ubiquinone is considered a large molecule and cannot be absorbed into the lower layers of skin. This is why it is believed to be such an effective antioxidant: it protects our skin in the upper layers and prevents damage in the deeper layers.

When used in sunscreen, ubiquinone is shown to increase ingredient stability, increase SPF factor, and add to infrared protection.

Fun fact: ubiquinone is fat-soluble.

Similar Comparisons