Cart
0
Spend £85.00 more for a free Medik8 Vanity Case
By Dr Ommid Rafie, GMC-registered doctor and founder of MedSkin Studios, Didsbury, Manchester.
The question I'm asked most often in clinic about Medik8 isn't whether to use Crystal Retinal, it's which number. The range runs from 1 to 24, and the numbers aren't arbitrary: each one is the concentration of retinaldehyde in the formula. Crystal Retinal 3 is 0.03%, 6 is 0.06%, 10 is 0.1%, 20 is 0.2%. Here's how I help patients choose, and how we move them up the ladder.
At a glance
| Strength | Retinaldehyde | Who it's for |
|---|---|---|
| Crystal Retinal 1 | 0.01% | Never used vitamin A; sensitive or rosacea-prone skin |
| Crystal Retinal 3 | 0.03% | New to retinoids, normal or combination skin |
| Crystal Retinal 6 | 0.06% | Comfortable on an over-the-counter retinol for 3+ months |
| Crystal Retinal 10 | 0.1% | Experienced users with no irritation at 6 |
| Crystal Retinal 20 / 24 | 0.2% / 0.24% | Worked up through the range over a year or more |
Why retinal, and why a ladder at all?
Retinaldehyde (retinal) sits one step closer to retinoic acid than retinol does, so skin converts it more directly. Medik8 encapsulates it to make it more stable and better tolerated. The trade-off with any vitamin A is that skin needs time to adapt, which is why a graduated range exists. Starting too high is the single most common reason people give up on retinoids. If you'd like the background on the retinol-versus-retinal distinction, I've written it up separately in Retinal vs Retinol: A Doctor's Guide.
Where to start
- Never used vitamin A, or sensitive / rosacea-prone skin: Crystal Retinal 1. It is deliberately gentle. If your skin is reactive, this is the one.
- New to retinoids, normal or combination skin: Crystal Retinal 3. This is where I start most patients, and it's the strength inside both the Nighttime Nourish and Rejuvenation Routine gift sets for good reason.
- Used an over-the-counter retinol comfortably for 3+ months: Crystal Retinal 6. A sensible entry point if you already tolerate vitamin A.
- Experienced retinoid user, no irritation at 6: Crystal Retinal 10.
- Crystal Retinal 20 and 24: for people who have worked up through the range over a year or more. I don't recommend jumping straight here, however resilient your skin feels.
When to step up
A simple rule: finish the bottle. One 30ml bottle used nightly lasts roughly eight to ten weeks. If, by the end of it, your skin is comfortable with no flaking, stinging or redness the next morning, move up one strength. If you're still getting the odd dry patch, stay where you are for another bottle. There's no prize for speed; the results come from years of consistent use, not from the number on the tube.
How to use it without irritation
- Cleanse and pat dry. Damp skin absorbs more, which sounds good but increases stinging.
- Apply a pea-sized amount to the whole face in the evening, avoiding the eyelids and the corners of the nose and mouth.
- For the first two weeks, use it every other night. Then nightly if comfortable.
- Follow with a moisturiser. Advanced Night Restore is the one Medik8 pairs it with, and it's what's in the Nighttime Nourish set.
- Wear SPF every morning, without exception. Retinoids make skin more sun-sensitive. Advanced Day Ultimate Protect SPF50+ is a moisturiser and sunscreen in one, which makes it easy.
If you want vitamin A around the eyes, don't push the face serum into that area; the Crystal Retinal Ceramide Eye range is formulated for it, and follows the same 3 / 6 / 10 ladder.
Who should not use it
Vitamin A products are not recommended during pregnancy or breastfeeding. If you have an active skin condition such as eczema, psoriasis or a flare of rosacea, speak to a doctor before starting. And if you're already on a prescription retinoid (tretinoin, adapalene), don't layer Crystal Retinal on top of it.
The short version
Start on 3 (or 1 if sensitive), use it every other night for two weeks then nightly, finish the bottle, and only then move up. Pair it with a moisturiser at night and SPF50 every morning. If you're unsure, ask us; it's a two-minute conversation and we'd rather you buy the right strength than a stronger one.
Frequently asked questions
Can I use Crystal Retinal every night from the start?
I'd rather you didn't. Every other night for the first two weeks lets skin adapt; most people can then go nightly without a problem.
Can I use it with vitamin C?
Yes: vitamin C in the morning, Crystal Retinal at night. They don't need to be in the same routine.
What if I get flaking or redness?
Drop back to every other night, or every third night, and use more moisturiser. If it persists beyond a couple of weeks, drop down a strength. Mild dryness is normal early on; stinging or a rash is not, so stop and ask.
How do I know the product is genuine?
MedSkin Studios is an authorised Medik8 stockist, so everything is official UK stock with the same batch codes and expiry dates you'd get from Medik8 directly.
Last reviewed 29 October 2026. MedSkin Studios is an authorised UK stockist of Medik8. Everything we sell is supplied through official channels and dispatched from Manchester. Free UK delivery on orders over £50.
