Crystal Retinal 6
Reviewed by SerumTruth Editorial · Price and formula checked July 2026
Retinal is among the best-evidenced cosmetic retinoids, and this is a careful version of it: encapsulated, disclosed and properly packaged, with a strength ladder to grow into. You pay a mid-tier price for the delivery and the stability. On evidence and formulation it earns it.
- Built on strong-evidence actives
- Every active discloses its concentration
- Encapsulated delivery protects and time-releases the active
- Air- or light-sensitive actives in protective, opaque packaging
- Evidence30 / 30
Strength of the research behind the key actives
- Retinaldehyde: strong evidence
The average of the key actives’ evidence grades.
- Potency21 / 25
Dosed at studied levels, not fairy-dusted
- Retinaldehyde (0.06%): dosed at a studied level
How strongly the actives are dosed, led by the strongest, not how many there are.
- Delivery & stability18 / 20
Delivery tech + packaging that protects fragile actives
- Delivery: encapsulated (protects and time-releases the active)
- Packaging: opaque tube
- Air- or light-sensitive actives (Retinaldehyde), so packaging is scored.
Delivery tech plus packaging, and packaging only counts when actives are fragile.
- Formulation8 / 10
Disclosure, active breadth, and ingredient generation
- 1 of 1 actives disclose a concentration
- 1 key active (breadth credit caps at 3)
- Current-generation or synergistic: Retinaldehyde
Disclosure, active breadth, and current-generation or synergistic actives.
- Value11 / 15
What a month of use costs vs. the category
- About $26 per month to use
- $87 for 30 ml, used about once a day (about 0.3 ml each time), so a bottle lasts about 3.3 months
- Frequency is set by Retinaldehyde, which is used no more than 7x a week, so a bottle stretches further
What a month of use costs: full marks at $6 a month or less, the floor at $60 a month or more.
Tap any row to see how its score was built.
Ranks #7 of 25 retinoids serums we have scored.
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What’s inside
| Active | Disclosed | Dose |
|---|---|---|
| Retinaldehyde | 0.06% | Studied |
A stabilised 0.06% retinaldehyde serum, the retinoid one conversion step closer to retinoic acid than retinol, so it works at a lower percentage. Medik8 encapsulates it and ships it in an opaque, air-limiting tube, which is exactly what a fast-oxidising retinoid needs. The "6" marks the strength, and the range steps up gradually so skin can build tolerance.
How it’s delivered
Air- and light-sensitive actives (vitamin C, copper peptides) lose potency fast in the wrong packaging, so delivery and the bottle are scored, not just what’s on the label.
The actives, explained
What the research says
Clinical studies using skin replica image analysis suggested topical retinaldehyde supported a better looking appearance of photoaged skin, well tolerated.
Clinical use of topical retinaldehyde on photoaged skin. Dermatology, 1999. PubMed ↗
A study of the active, not this exact product. What matters for the score is whether this serum uses it at a comparable dose.
Higher-scoring alternatives
Same category, better SerumProof score. Worth a look before you buy.
Revision history
- July 11, 2026Price and formula rechecked
- July 10, 2026Review published
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Cosmetic information for general education, not medical advice. The SerumProof score reflects our reading of publicly available research and formulation disclosures. See how scoring works.