Retinal vs retinol: why it’s stronger and how to use it
What retinal is and how it differs from retinol
Retinal (retinaldehyde) is a vitamin A derivative used in skincare that sits one step away from active retinoic acid in the metabolic pathway. It is a more advanced metabolite than retinol in the transformation cascade towards retinoic acid. It needs only one enzymatic conversion to become active; retinol needs two. That translates directly into speed and intensity of results on the skin.
In products like Medik8 Crystal Retinal, the retinaldehyde is stabilised to maintain its bioactivity and prevent premature oxidation. An oxidised retinal molecule before it penetrates the skin is essentially useless: that stabilisation is what separates a serum that delivers results from one that does very little.
- Retinal is a vitamin A derivative that requires a single enzymatic step to convert into active retinoic acid in the skin.
- Retinol needs two metabolic conversions to reach retinoic acid, so it usually acts more slowly than retinal.
- Stabilised retinal formulations reduce oxidation, helping maintain potency until the ingredient reaches the skin.
Conversion chain and clinical potency
The key conversion is from aldehyde to carboxylic acid, catalysed by aldehyde dehydrogenase (ALDH). This step is efficient in most skin types, which helps explain the faster action compared with standard retinol serums. The core reference here is Fluhr et al., 1999 (PMID 10416521), which compares different topical vitamin A derivatives.
- Retinal is converted into retinoic acid in the skin by aldehyde dehydrogenase enzymes in a single metabolic step.
- Efficient ALDH activity in most people explains why retinal often works faster than cosmetic-strength retinol.
- Local enzyme expression means each area of skin can regulate how much active retinoic acid is generated from retinal.
Retinal and acne: antibacterial activity
Retinal has demonstrated in vitro antibacterial activity against Propionibacterium acnes (now called Cutibacterium acnes) (Péchere et al., 1999). It works on two fronts: it normalises keratinisation and helps clear clogged pores, and it directly inhibits bacterial growth on the skin surface.
For comedonal or comedonal-inflammatory acne in adults, combining a retinal serum with niacinamide often gives visible improvement in inflammation within 2–3 weeks and better texture control by around 6–8 weeks. In my experience at the pharmacy counter, this direct antibacterial activity makes it more useful than retinol alone for this specific acne profile.
- In vitro studies show retinal can inhibit the growth of acne-associated bacteria such as Cutibacterium acnes.
- Topical retinal helps normalise follicular keratinisation, reducing blocked pores that drive comedonal acne.
- For mild-to-moderate adult acne, retinal can complement niacinamide or topical antibiotics without replacing systemic treatment when needed.
Profiles: who should (and should not) use it
You want to reduce wrinkles and improve firmness within roughly 12 weeks. A concentration around 0.1% is ideal if you have already used a cosmetic retinol product before.
If you are prone to redness, a retinal serum at about 0.05–0.06% is often better tolerated than standard over-the-counter retinol. Pair it with niacinamide and hyaluronic acid for maximum comfort.
You are looking for pore normalisation, sebum control and some antibacterial effect in a single evening step. Start around the 0.05–0.06% level unless your skin is already used to stronger actives.
All topical retinoids should be avoided during pregnancy and breastfeeding. Oral retinoids are clearly teratogenic. Even though absorption from the skin is low, current guidance is to avoid them as a precaution.
pdIf you have had urticaria or dermatitis triggered by retinol or tretinoin, avoid retinal as well. Allergies to retinoids tend to be class-specific. Consider stabilised vitamin C or niacinamide instead for anti-ageing benefits.
pd- Retinal serums are suitable for many adults focused on anti-ageing or mild-to-moderate acne if pregnancy is not a factor.
- People who are pregnant or breastfeeding are advised to avoid all topical retinoids as a precautionary measure.
- A history of allergic reactions to other retinoids is a strong reason not to use retinal-based skincare products.
Medik8 Crystal Retinal: which one to choose
My practical advice with Medik8 Crystal Retinal is simple: start with Crystal Retinal 6 (0.06%). It is usually better to introduce it slowly and then move up than to start too strong and give up because of irritation. Long-term adherence is what really drives meaningful anti-ageing results.
pd- Medik8 Crystal Retinal comes in graded strengths so you can build tolerance gradually over several months.
- Starting at around 0.06% retinal helps minimise irritation while your skin barrier adapts to vitamin A derivatives.
- Consistent long-term use of an appropriate strength matters more than jumping straight to the highest concentration.
Step-by-step introduction protocol
pd pdWeeks 1–2: “Low and slow”
pdUse Crystal Retinal 6 one night per week. Apply on completely dry skin (wait about five minutes after cleansing). Dose: roughly a grain-of-rice amount for the whole face. If you feel tightness, layer a hyaluronic acid serum beforehand.
pdWeeks 3–4: two nights per week
pdIncrease to Monday and Thursday nights, always leaving rest days between applications. If you develop marked redness or flaking, drop back to once weekly for another week or two before trying again.
pdComparison table: Retinal (retinaldehyde)
| Molecule | Steps to retinoic acid | Relative efficiency | Tolerance |
|---|---|---|---|
| Retinyl palmitate | 3 enzymatic steps | 100% (reference) | Very good |
| Retinol | 2 enzymatic steps | ~150-200% | Good |
| Retinal (retinaldehyde) | 1 enzymatic step | ~2,200% (11× higher than retinol) | Excellent |
| Tretinoin (retinoic acid) | 0 steps (already active) | Maximum | Poor (prescription only) |
Preguntas frecuentes
Referencias científicas
