2Rank 02 of 8 · Best Retinol Serums
Medik8 Medik8 Crystal Retinal 6
Cyclodextrin-encapsulated retinaldehyde in a formula built for stability — antioxidants, a chelator and titanium dioxide as an opacifier. A five-step strength ladder lets you build tolerance properly.
8.3BPR score
- €65Price
- Retinaldehyde 0.06% — not covered by the EU capRetinoid form and stated concentration
- 2 of 8in Best Retinol Serums
- 8.3BPR score 0–10
Review
What this product is
Written after the analysis, from the same sources the score is built on: the manufacturer's documentation, available studies and verified owner feedback.
This is the most carefully formulated product in the ranking, and the formulation is where the money goes rather than the concentration.
The active is retinaldehyde at 0.06%, encapsulated in what Medik8 describes as a crystal-shaped cyclodextrin system acting as "a time-release mechanism as well as a stability enhancer". Retinal is not one of the three substances restricted by Regulation (EU) 2024/996, so this product is unaffected by the 0.3% cap — and Medik8 has been explicit about using that as its compliance strategy, discontinuing two of six EU retinol products and redirecting customers to retinaldehyde.
The supporting formula is unusually thorough about protecting the active. Squalane and sodium hyaluronate for the base, tocopheryl acetate, ethyl ascorbic acid and tetrahexyldecyl ascorbate as antioxidants, BHT, disodium EDTA as a chelator, and — notably — titanium dioxide as an opacifier, protecting the retinoid from light through the formula itself rather than relying only on the bottle.
The strength ladder is the practical advantage. Crystal Retinal runs 1 (0.01%), 3 (0.03%), 6 (0.06%), 10 (0.1%) and 20 (0.2%). Retinisation — the irritation phase when starting a retinoid — is the main reason people abandon them, and a five-step ladder lets you climb at your own pace rather than jumping from nothing to a strong product.
Two honest caveats. Medik8's evidence base includes published peer-reviewed retinaldehyde studies, including a 229-patient trial, but the company states it has no independent third-party lab verification, and no clinical data specific to Crystal Retinal itself is published. And the widely repeated "11 times faster than retinol" claim appears on Medik8's consumer page with no citation at all; on its technical page it is traced to Siegenthaler et al. 1990, an in-vitro enzyme-kinetics measurement.
Note that this formula contains ascorbate derivatives in the same bottle as the retinoid — direct commercial refutation of the "never combine retinol with vitamin C" rule.
Technical data
Specification
Figures from the manufacturer's documentation, verified against available outside sources. Values we could not confirm are marked as declared.
- Retinoid form
- Retinaldehyde (retinal)
- Stated concentration
- 0.06%
- Covered by EU 0.3% cap
- No
- Encapsulated
- Yes - cyclodextrin, time-release and stability
- Key supporting ingredients
- Squalane, sodium hyaluronate, tocopheryl acetate, ethyl ascorbic acid, tetrahexyldecyl ascorbate
- Stability system
- BHT, disodium EDTA, titanium dioxide opacifier
- Size
- 30 ml
- Price per ml
- approx. EUR 2.16 (RRP EUR 3.28)
- Strength ladder
- CR1 0.01%, CR3 0.03%, CR6 0.06%, CR10 0.1%, CR20 0.2%
- Independent verification
- None, per the brand
Component scores
Where the score
comes from.
Four components, equal weight, each on a 0–10 scale and each resting on a named source. The overall score is their mean — the full procedure is in the methodology.
What we liked
- Retinaldehyde — not covered by the EU 0.3% cap
- Cyclodextrin encapsulation for time-release and stability
- Titanium dioxide opacifier protects the active from light
- Full antioxidant and chelator system: tocopheryl acetate, BHT, disodium EDTA
- Five-step strength ladder (0.01% to 0.2%) for building tolerance
- Medik8 has published peer-reviewed retinaldehyde research
Worth knowing
- €64.69 for 30 ml — €2.16 per ml, among the most expensive here
- No independent third-party lab verification, by the brand's own statement
- No published clinical data specific to Crystal Retinal itself
- The 11x potency claim appears uncited on the consumer page
- RRP of €98.50 means the price you see varies enormously by retailer
Comparison
How it compares
within the category
All values come from the same analysis and are comparable only within the category Best Retinol Serums.
| Product | Score | Retinoid form and stated concentration | Price |
|---|---|---|---|
| Geek & Gorgeous A-Game 10Top score | 8.8 | Retinaldehyde 0.1% — not covered by the EU cap | €19 |
| Medik8 Crystal Retinal 6This product | 8.3 | Retinaldehyde 0.06% — not covered by the EU cap | €65 |
| Category average8 products analysed | 7.9 | — | — |
FAQ
Frequently asked questions
Is 0.06% retinal weaker than 0.5% retinol?
Not necessarily, and the honest answer is that we cannot give you a clean conversion. Retinaldehyde converts to retinoic acid in one step where retinol needs two, and a 1990 in-vitro enzyme study measured retinal converting at 51.6 versus retinol's 4.49 pmol per hour per mg protein. But that is a metabolic rate in a cell assay, not a clinical outcome comparison. Treat retinal as meaningfully more potent per unit than retinol, without attaching a multiplier to it.
Which strength should I start on?
The lowest one you can find, on the American Academy of Dermatology's advice: use the least intense formula available, every other night to start, building up by tolerance. The point of the five-step ladder is that you do not have to guess. Note that AAD specifically warns that in darker skin tones, retinoid irritation can trigger post-inflammatory hyperpigmentation, which is a reason to climb slowly rather than quickly.
From the same ranking
Other products in Best Retinol Serums.
The same protocol, the same key parameter, the same set of sources.
-
No. 018.8/ 10
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CeraVe Resurfacing Retinol Serum
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Retinol at exactly 0.3%, the maximum the EU now permits, with ceramides and peptides. The one…