Medik8

Crystal Retinal 6

SerumLuxuryEvening only
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A stabilised retinaldehyde serum (0.06%) with hyaluronic acid and vitamin E, sitting between retinol and prescription tretinoin in strength. Faster-acting than retinol with good tolerability; part of a tiered ladder you climb gradually.
The verdict

What this is good for

✓ Great forFine LinesPhotoaging PreventionRough Texture
The formulation

Ingredient stack

Each ingredient is listed in descending concentration. Above the 1% line the order is regulated — below it, brands can list in any order.

Ingredients above the dashed gold line are dosed above 1% (the regulatory threshold) — these are what the formulation is really built on. Percentages are positional estimates from INCI order unless a brand discloses them.

~50–80%Aqua
~5–25%Glycerin
~3–10%Caprylic/Capric…
~2–6%Dimethicone
~1.5–4%Retinal
~1–2%2 ingredients
≤ 1% each3 more ingredients below 1%
position-estimated %1% regulatory line
Hero actives

What's actually doing the work

Retinaldehyde
Retinal
Retinoid
A key active in this formula. See the glossary for the full breakdown of how Retinaldehyde works, the evidence behind it, and how to use it.
Full glossary entry →
Hyaluronic Acid
Sodium Hyaluronate
Acid
A humectant that binds water in the upper skin layers for immediate plumping and hydration. Multi-weight forms reach different depths. Apply to damp skin and seal with moisturiser, especially in dry climates.
Full glossary entry →
Vitamin E
Tocopherol
Antioxidant
A lipid-soluble antioxidant (tocopherol) that protects cell membranes from oxidation and works synergistically with vitamin C and ferulic acid to stabilise and boost antioxidant defence.
Full glossary entry →
When to use

Routine placement

Evening only
Cheaper alternatives

Looking for a dupe?

The closest active-matched alternative is the Estée Lauder Advanced Night Repair Synchronized Multi-Recovery Complex (77% active overlap). We found 6 options that share this product’s hero actives.

Dupe guide
See all serum dupes for this product
Ranked by ingredient overlap, with an honest note on what’s different in each.
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Next steps

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See how this product fits alongside everything else you’re using — conflicts, gaps, overlap.

Skin Stacker is independent and receives no payment from any brand. Ingredient analysis is based on publicly disclosed INCI lists and the peer-reviewed literature. Percentages are positional estimates from INCI order unless a brand discloses them. Formulations change — always re-check the label on your specific batch before using.