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By Mari, founder of K Skin Aura
Ingredient guide6 min readPrices checked 8 Nov 2026
Retinal, PDRN, peptides, NAD+. They're on every serum right now. Here's what each one does, who it suits and where it goes in your routine.
The short answer
Start with one. Retinal has the strongest evidence for fine lines, but it needs a slow start. PDRN and peptides are gentler, so they suit sensitive skin. NAD+ is the newest, with the least evidence so far.
You don't need all four. Read the one that fits your skin, or skip to find your match.
1
Retinal
The proven one
What it is
A form of vitamin A. Your skin turns it into retinoic acid, the form that does the work. Retinoids are the most studied anti-ageing ingredients in skincare.
The family, from gentlest to strongest
RetinolTwo steps to retinoic acid. The familiar one.
HPR (hydroxypinacolone retinoate)A newer retinoid ester. Brands say it needs no conversion.
Retinal (retinaldehyde)One step to retinoic acid. Works faster.
TretinoinRetinoic acid itself. Prescription only.
How strong is the evidence?
Strong. Decades of research on retinoids for fine lines and texture. The biggest studies are on prescription tretinoin. Studies on retinal and retinol are smaller, but they point the same way.
What it does
Speeds up skin renewal. Over time it softens the look of fine lines, smooths texture and evens tone.
Who it suits
Fine lines, rough texture, uneven tone. Sensitive skin can use it too, slowly.
Skip it if
You are pregnant or breastfeeding, or you already use a prescription retinoid.
How to use
Evenings only. Start on two or three nights a week, a pea-sized amount, then moisturiser. SPF every morning.
Where it goes
Cleanse
Toner
SerumPM
Cream
SPFAM
Plays well with
NiacinamidePeptidesPDRNCeramide cream
Keep apart
Exfoliating acids (AHA, BHA) on the same nightA second retinoid product
Good to know: One strong active per routine, never an exfoliating acid (AHA or BHA) on retinal nights. Barrier first, always. Some dryness or flaking in the first weeks is common. If it stings, use it less often.
Our picks
1
Gentlest start
Gentlest startPurito
TXA 6% + Niacinamide 10% + Retinal Serum
A very low dose of retinal, with 6% TXA and 10% niacinamide for dark marks.
£19.99Add to bag
2
Three retinoids
Three retinoidsepii
HPR Pro Shot: HPR + Retinal + Retinol
HPR, retinal and retinol in modest amounts, with ectoin and panthenol. Evenings only.
£23.99Add to bag
3
Ready for more
Ready for moreCelimax
The Vita-A Retinal Shot Tightening Booster
Retinal with Matrixyl 3000 peptides and niacinamide. For skin already used to retinoids.
£18.00View
New to retinal? Our week-by-week retinal plan shows how to start.
Not sure what counts as an active, or how strong each one is? See what actives are in skincare.
2
PDRN
The gentle bounce
What it is
Polydeoxyribonucleotide: purified fragments of DNA, usually from salmon. On the label it often appears as sodium DNA. It came to skincare from Korean skin clinics, where it's injected.
How strong is the evidence?
Early. Most PDRN research is on injections, not creams. A 2025 review of polynucleotides, the family PDRN belongs to, found just nine small studies, all injections, rated low to moderate quality. Promising, but not proven in a cream yet.
What it does
Helps skin feel hydrated, calm and bouncier.
Who it suits
Sensitive skin, early fine lines, or anyone who finds retinoids too much.
Skip it if
You avoid animal-derived ingredients. Most PDRN comes from salmon.
How to use
Morning and evening, after toner and before moisturiser.
Where it goes
Cleanse
Toner
SerumPDRN
Cream
SPFAM
Plays well with
Retinal nightsVitamin CNiacinamidePeptides
Good to know: “PDRN” on the front doesn’t tell you how much is inside. Some masks contain very little, so we sell those as hydration masks, not PDRN treatments.
Our picks
1
Hydration first
Hydration firstAnua
PDRN Hyaluronic Acid Capsule 100 Serum
Salmon PDRN with eight forms of hyaluronic acid. Dewy, light and quick to sink in.
£20.00Add to bag
2
Cream step
Cream stepDr.Reju-All
Advanced PDRN Rejuvenating Cream
A small gel-cream tube: salmon PDRN plus 2% niacinamide. Best at night.
£22.90Add to bag
3
Mari uses this
Mari uses thisMedicube
Salmon PDRN with collagen and peptides, in a light serum. Fragrance listed.
“I have used it a few times, it’s very gentle.” Mari
£19.99Add to bag
The PDRN pair: Anua PDRN Hyaluronic Acid Capsule 100 Serum + Dr.Reju-All Advanced PDRN Rejuvenating Cream
£42.90 · one bag, two steps
3
Peptides
The quiet helpers
What they are
Short chains of amino acids, the building blocks of protein. Different peptides do different jobs, so read which ones a product contains.
The ones you'll see on labels
Signal peptidese.g. palmitoyl pentapeptide-4 (Matrixyl), palmitoyl tripeptide-38 (Matrixyl Synthe’6), palmitoyl tripeptide-5
Copper peptidese.g. copper tripeptide-1 (GHK-Cu)
Peptide blendsSeveral peptides together, often with collagen
How strong is the evidence?
Some. The best-known study is a 12-week trial of Matrixyl (palmitoyl pentapeptide-4), which found improvements in fine lines. Many other peptides have only small or brand-run studies.
What it does
Support the look of firmness and smoothness.
Who it suits
Early fine lines, loss of bounce, sensitive skin.
Skip it if
You want fast, visible change. Peptides work slowly.
How to use
Morning and evening, after toner and before moisturiser.
Where it goes
Cleanse
Toner
SerumPeptides
Cream
SPFAM
Plays well with
RetinalPDRNHyaluronic acidNiacinamide
Our picks
1
Matrixyl inside
Matrixyl insideepii
10% HPT with 2% Matrixyl Synthe’6, panthenol and ectoin. No retinoid.
£36.99Add to bag
2
Watery and light
Watery and lightPurcell
A peptide ferment is the first ingredient, with palmitoyl tripeptide-5 and collagen.
£26.00Add to bag
3
Copper + PDRN
Copper + PDRNDr.Reju-All
Advanced PDRN Copper Peptide Serum
Copper tripeptide-1, a peptide blend and salmon PDRN. Morning and night.
£28.99Add to bag
4
NAD+
The new one
What it is
A molecule every cell uses to make energy. Levels fall as we age. Skincare uses NAD+ itself, or ingredients skin can turn into NAD+, like NMN and niacinamide.
How strong is the evidence?
Very early. Most NAD+ research is lab work on skin cells. Whether NAD+ in a cream reaches those cells is still an open question. Niacinamide, which skin uses to make NAD+, has much stronger evidence.
What it does
Brands position it for tired, dull-looking skin.
Who it suits
Dull, tired-looking skin, and anyone who likes trying new ingredients.
Skip it if
You want proven results. Put your money into SPF and retinal first.
How to use
Morning or evening, in place of your toner, essence or cream.
Where it goes
Cleanse
TonerNAD+
Serum
Cream
SPFAM
Plays well with
NiacinamidePDRNRetinalPeptides
Our picks
1
Two creams in one
Two creams in oneepii
Double Up Cream NAD+ NMN & TXA
NAD+ and NMN on one side, TXA and niacinamide on the other. Your last step.
£23.99Add to bag
2
Easiest start
Easiest startNumbuzin
No.9 NAD+ PDRN Glow Boosting Toner
A toner with NAD+, salmon PDRN, niacinamide and peptides. Step one.
£17.00Add to bag
3
Silky essence
Silky essenceNumbuzin
No.9 NAD+ Bio Lifting-sil Essence
A stretchy essence with NAD+, niacinamide and peptides.
£22.99Add to bag
Find your match
Start with your main goal. One ingredient is enough to begin.
Softer-looking fine lines
Your match
RetinalWhy
The strongest evidence of the four.
Shop it
Sensitive skin, gentle start
Your match
PDRNWhy
Calm and hydrating, with no retinoid or acid.
Shop it
Skin losing its bounce
Your match
PeptidesWhy
Gentle, with no retinoid, morning and night.
Shop it
Lines and dark marks
Your match
Retinal + TXAWhy
One serum covers both, with a very low dose of retinal.
Shop it
Fine lines around the eyes
Your match
Retinal (eye serum)Why
Made for the thinner skin around the eyes.
Shop it
Dull, tired skin
Your match
NAD+Why
Swap it in as your moisturiser. Nothing extra to add.
Shop it
How it fits together
Morning
- 1Cleanse
- 2PDRN or peptides
- 3Moisturiser
- 4SPF
Evening
- 1Cleanse
- 2Retinal (2 to 3 nights a week)
- 3Moisturiser
Other nights: PDRN or peptides
Want this worked out for you? Our Age Defense Firming Routine comes with printed Blueprint Cards that show when to bring in retinal, week by week.
Not sure where to start?
Send me what you use now and what you'd like to change. I'll reply personally with the one ingredient I'd start with. You don't have to buy anything.
Ask meSkin Advice is a cosmetic routine review. It is not a diagnosis.
Frequently asked questions
What is the best anti-ageing ingredient?
Retinoids have the strongest evidence for fine lines and texture. If your skin is sensitive, PDRN or peptides are gentler places to start. Whatever you choose, daily SPF matters more than any of them.
What's the difference between retinol and retinal?
Your skin converts both into retinoic acid, the form that works. Retinal needs one step, retinol needs two, so retinal can work faster at a lower strength.
Is PDRN vegan?
Usually not. Most PDRN comes from salmon, and on the label it often appears as sodium DNA. Every PDRN product in this guide is salmon-derived, so check the label if you avoid animal-derived ingredients.
Can I use retinal and PDRN together?
Yes. They do different jobs, so many people use retinal at night and PDRN in the morning, or PDRN on the nights they skip retinal.
Does NAD+ in skincare actually work?
It's too early to say. Most NAD+ research is lab work on skin cells, and human studies on NAD+ creams are scarce. Niacinamide, which skin uses to make NAD+, has much stronger evidence.
Can I use these if I'm pregnant?
Avoid retinal and other retinoids if you're pregnant or breastfeeding. For anything else, check with your GP or midwife first.
About Mari. Mari is the founder of K Skin Aura, a UK Korean skincare retailer. She has been obsessed with skincare since her teens and experimented heavily, which damaged her skin barrier. She rebuilt it by learning to read ingredient lists and studying Korean skincare, which she loves. After a trip to South Korea she started selling Korean skincare in April 2025. She reviews cosmetic routines and product choices through K Skin Aura's free Skin Advice service. She is not a dermatologist or clinician.
Sources checked. Mukherjee et al., Retinoids in the treatment of skin aging, Clinical Interventions in Aging (2006) · Lampridou et al., The effectiveness of polynucleotides in esthetic medicine: a systematic review, Journal of Cosmetic Dermatology (2025) · Robinson et al., Topical palmitoyl pentapeptide provides improvement in photoaged human facial skin, International Journal of Cosmetic Science (2005) · Kang et al., Skin fibroblast responses to nicotinamide mononucleotide, Biomedicines (2025) · K Skin Aura product pages and ingredient lists, checked 8 November 2026.
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