Medik8 Crystal Retinal 20 Versus Paula's Choice Pro Retinaldehyde Dual-Retinoid Treatment

Medik8 Crystal Retinal 20 Versus Paula's Choice Pro Retinaldehyde Dual-Retinoid Treatment

This anti-aging treatment is formulated around Retinal and Hyaluronic Acid to soften the look of wrinkles and refine skin texture.

This anti-aging treatment is formulated around Retinal and Oleyl Adapalenate to soften the look of wrinkles and refine skin texture.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Retinal 0.2%

Hyaluronic Acid

Caprylic/Capric Triglyceride

Glycerin

Isododecane

Cyclodextrin

Cetearyl Alcohol

Cetearyl Olivate

Sodium Acrylate/Sodium Acryloyldimethyl Taurate Copolymer

Sorbitan Olivate

Tocopheryl Acetate

Squalane

Sodium Hyaluronate

3-O-Ethyl Ascorbic Acid

Daucus Carota Sativa Seed Oil

Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer

Ethylhexylglycerin

Pentylene Glycol

Vanilla Planifolia Fruit Extract

Hydroxypropyl Methylcellulose

Rubus Chamaemorus Seed Oil

Sodium Polyaspartate

Tetrahexyldecyl Ascorbate

Dipteryx Odorata Bean Extract

BHT

Polyhydroxystearic Acid

Disodium EDTA

Hydroxyacetophenone

Titanium Dioxide

Phenoxyethanol

Alumina

Lonicera Caprifolium Flower Extract

Isostearic Acid

Lecithin

Lonicera Japonica Flower Extract

Polyglyceryl-3 Polyricinoleate

Stearic Acid

Coumarin

CI 14700

Retinal 0.2%, Hyaluronic Acid, Caprylic/Capric Triglyceride, Glycerin, Isododecane, Cyclodextrin, Cetearyl Alcohol, Cetearyl Olivate, Sodium Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Sorbitan Olivate, Tocopheryl Acetate, Squalane, Sodium Hyaluronate, 3-O-Ethyl Ascorbic Acid, Daucus Carota Sativa Seed Oil, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Ethylhexylglycerin, Pentylene Glycol, Vanilla Planifolia Fruit Extract, Hydroxypropyl Methylcellulose, Rubus Chamaemorus Seed Oil, Sodium Polyaspartate, Tetrahexyldecyl Ascorbate, Dipteryx Odorata Bean Extract, BHT, Polyhydroxystearic Acid, Disodium EDTA, Hydroxyacetophenone, Titanium Dioxide, Phenoxyethanol, Alumina, Lonicera Caprifolium Flower Extract, Isostearic Acid, Lecithin, Lonicera Japonica Flower Extract, Polyglyceryl-3 Polyricinoleate, Stearic Acid, Coumarin, CI 14700

Water

Simmondsia Chinensis Seed Oil

Dimethicone

Polyglyceryl-2 Stearate

Propanediol

Polyglyceryl-3 Diisostearate

Sodium Stearoyl Glutamate

Retinal

Oleyl Adapalenate

Tocopherol

Saccharomyces Ferment Filtrate

Albatrellus Confluens Extract

Punica Granatum Pericarp Extract

Glyceryl Stearate

Stearyl Alcohol

Hydroxyapatite

Butylene Glycol

Cetyl Glyceryl Ether

Ricinus Communis Seed Oil

Sodium Polyacrylate

Isopropyl Myristate

Caprylhydroxamic Acid

Sodium Phytate

Xanthan Gum

Hydroxystearic Acid

Ceramide AP

1,2-Hexanediol

Sorbitan Oleate

Naringin

Citric Acid

Water, Caprylic/Capric Triglyceride, Simmondsia Chinensis Seed Oil, Dimethicone, Polyglyceryl-2 Stearate, Propanediol, Polyglyceryl-3 Diisostearate, Sodium Stearoyl Glutamate, Retinal, Oleyl Adapalenate, Tocopherol, Tocopheryl Acetate, Saccharomyces Ferment Filtrate, Albatrellus Confluens Extract, Punica Granatum Pericarp Extract, Glyceryl Stearate, Stearyl Alcohol, Hydroxyapatite, Butylene Glycol, Cetyl Glyceryl Ether, Ricinus Communis Seed Oil, Sodium Polyacrylate, Isopropyl Myristate, Hydroxyacetophenone, Caprylhydroxamic Acid, Sodium Phytate, Xanthan Gum, Glycerin, Hydroxystearic Acid, Ceramide AP, 1,2-Hexanediol, Sorbitan Oleate, Naringin, Citric Acid, Titanium Dioxide

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Alternatives

Ingredients Explained

These ingredients are found in both products.

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

Caprylic/Capric Triglyceride (aka MCT Oil) is a lightweight emollient, solvent, and texture enhancer. It is considered a skin-softener by helping to prevent moisture loss.

Though it behaves like an oil, it is not technically one due to its chemical composition. One perk of this ingredient is that it is very stable, resistant to oxidation, and unlikely to go rancid.

In practice, that translates to a long shelf life and a consistently elegant skin feel.

While there is an assumption Caprylic Triglyceride can clog pores due to it being derived from coconut oil, there is no research supporting this. Just patch test if you have concerns.

Fractionated coconut oil and MCT Oil are both listed as Caprylic/Capric Triglyceride according to INCI. This is because INCI names are based on the ingredient’s final chemical composition and not its marketing name or source.

This ingredient is treated as the gold standard fungal acne safe oil. Even though it is coconut derived, the problematic lauric acid is stripped out.

This leaves just caprylic (C8) and capric (C10) acid. These chain lengths actually trend antifungal; a 2020 study found caprylic acid was enough to disrupt Malassezia furfur cell membrane, with a caprylic acid derivative damaging membrane structures at concentrations as low as 0.2%.

Glycerin (or glycerol) is a compound naturally found in your skin. It's a powerhouse humectant that pulls water into the stratum corneum.

Topically, glycerin does several things at once:

Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.

Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.

This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.

Just know very high concentrations (>40%) can feel tacky in low humidity.

Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.

Hydroxyacetophenone is a small phenolic molecule that earns its place in a formulas as an antioxidant and preservative booster.

As a phenol, it is able to neutralize free radicals to protect both the product and the skin from oxidative stress.

Though it can't kill microbes on its own, it works as a good supporting agent when combined with other preservatives like Phenoxyethanol or 1,2-Hexanediol.

This ingredient naturally occurs as piceol in Norwegian spruce needles (~0.4-1.1% dry weight and in cloudberries). Though the cosmetic-grade material is synthesized for purity and consistency.

You'll usually see it used at low levels and suppliers recommend up to 1% added to a water phase.

Safety testing was done at concentrations like 0.05% in SPF products and 0.5% in a Human Repeated Insult Patch Test. The safety evidence is assuring; this ingredient is safe for cosmetics in current use and also holds safety status as a food flavoring as well.

An honest caveat: the "soothing" and "anti-inflammatory" claims come mostly from supplier marketing rather than published clinical trials. The Cosmetic Ingredient Review's own literature search found no useful efficacy studies on this ingredient.

So the antioxidant and preservative-boosting roles are the well supported ones while the calming benefit is plausible but thinly evidenced.

Overall, this is a well-tolerated, low-irritation multitasker that quietly helps a formula stay fresh and stable.

Retinal (aka retinaldehyde) is a form of retinoid that formulators use mainly as an antiaging and skin-renewing active.

What makes it special is its position in the retinoid family; skin converts it to retinoic acid (the prescription gold standard) in just one step.

Because retinal only requires 1 conversion step to become retinoic acid, it's the strongest over-the-counter retinoid. It also works at lower concentrations than retinol, since retinal is about 10x more bioavailable.

Studies back up its efficacy in skin:

A foundational trial showed that applying 0.05-0.5% retinal for 1-3 months produced a dose-dependent and significant increase in epidermal thickness + cell turnover markers.

And a head-to-head comparison of 0.05% retinal against a 0.05% retinoid acid found both formulations were effective for the basis of wrinkle/skin roughness features, but retinoic acid caused more local irritation.

More recent controlled trials confirm it improves wrinkles, dermal density, and firmness over 12-24 weeks, with significant improvements in skin texture and firmness (particularly with the higher 0.1% concentration).

Retinal also has one trick the other retinoids do not: it directly fights against acne bacteria since a clinical study showed retinaldehyde-treated areas displayed a significant decrease in counts of viable P. acnes.

This makes it a great pick for people who want to treat aging and breakouts.

Typical cosmetic use sits in the 0.05-0.1% range with 0.05% being the gentle starting point and 0.1% giving stronger results.

Like all retinoids, retinal works best with nightly use, a good moisturizer, and daytime sunscreen. It can cause some irritation so ease into it slowly rather than going all in.

The "ramp up" method works well: start with Retinal once a week to give your skin time to adjust, which keeps irritation low.

Slowly add more nights until you reach your goal frequency once your skin feels comfortable.

Retinoids also make your skin more sensitive to the sun in the first few weeks, so wear sunscreen every morning and protect your skin from direct sun while you build up tolerance.

Titanium Dioxide (TD) is a mineral UV filter widely used in sunscreens and cosmetics.

It's one of only two UV filters officially classified as "mineral" by regulatory agencies (the other being Zinc Oxide).

A really common myth is that mineral filters work by reflecting UV light off your skin like tiny mirrors.

They don't only do that; modern research shows TD protects mostly by absorbing UV radiation, the same way chemical filters do.

When researchers measured this, reflection accounted for only about 4-5% of the protection (and less than SPF 2 on its own). The other ~95% comes from absorption: the UV photons hit the particle and their energy gets soaked up by its semiconductor band gap rather than bouncing off.

So "reflects vs. absorbs" was never really the right way to split mineral from chemical filters.

TD gives broad-spectrum protection that's strongest in the UVB and UVA-2 range and weaker in the UVA-1 range. Its UVA protection isn't quite as strong as Zinc Oxide's which is why you'll often see the two paired together.

Together, they make a solid broad-spectrum system.

TD is a great pick for sensitive, acne-prone, or redness-prone skin because it's non-irritating and chemically inert. Regulatory reviews classify it as a non-sensitizer and mild-to-non-irritant.

It's also unlikely to cause the "eye sting" some chemical filters are known for.

The main trade-off is cosmetic; TD can leave a white cast and has a thicker texture. This is why mineral sunscreens are often less cosmetically elegant than chemical or hybrid formulas (and harder to shade-match on deeper skin tones).

Formulators often use micronized or nano-sized TD to cut down on white case and improve spreadability. Smaller particles scatter less visible light so the formula looks less chalky while still filtering UV.

TD is almost always bundled with coatings like Alumina, Silica, Stearic Acid, or Dimethicone. These coatings do two important jobs:

TD can be used at up to 25% in a finished sunscreen; this is the regulatory ceiling in both the US and the EU.

In practice, the amount in any given product varies a lot depending on the target SPF and whether it's paired with other UV filters.

TD is one of the most heavily vetted sunscreen ingredients out there. It is approved as a UV filter in all major markets worldwide, including the US, EU, UK, Japan, Korea, China, Australia, and Canada.

The safety evidence is solid. There was an old worry that nano particles might absorb through skin into the body but multiple studies (including on damaged, sunburned, and UV-irradiated skin) have shown that TD stays on the surface and the layer of dead skin cells on top of everything else.

There's also no evidence of carcinogenicity, mutagenicity, or reproductive toxicity from dermal exposure of this ingredient.

For those who have seen the headline about a 2022 EU ban on TD, that was on TD as a food additive (a complete separate use from topical sunscreen).

There are ongoing questions about how nano-TD might affect marine ecosystems. As of now, there has been no conclusive evidence that any form of TD (or any other sunscreen filter) harms coral reefs or marine life.

The science is still developing and it's a space worth watching rather than packing over.

However, several destinations have reef-safety sunscreen rules that restrict certain chemical filters and steer visitors toward mineral, non-nano options. If you're traveling somewhere with these rules, a non-nano mineral sunscreen is the safe bet.

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%.

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