Peptides, Ceramides and PDRN Explained: What the Evidence Says

Peptides, ceramides and PDRN show up on more and more skincare labels, often with big promises attached. They are very different ingredients with very different levels of evidence behind them. This guide explains what each one is, what the research actually supports, how to fit them alongside retinol and vitamin C, and how to use them to look after your skin barrier through a dry Canadian winter.

Ceramides: the most thoroughly supported of the three

Ceramides are lipids (fats) that your skin already makes. Together with cholesterol and free fatty acids, they form the "mortar" between the cells of the outermost skin layer, the stratum corneum, helping hold water in and keep irritants out. A 2025 narrative review on skin barrier repair describes ceramides as making up roughly half of the lipids in this layer, and summarizes studies in which ceramide-based formulations reduced transepidermal water loss and improved hydration compared with placebo.

What that means for you: a moisturizer with ceramides is a sensible, well-grounded choice for dry or easily irritated skin, especially in winter. Ceramides work well as part of a complete moisturizer that also contains humectants (like glycerin) and occlusives that slow water loss. You can browse ceramide skincare or our wider range of face moisturizers.

Peptides: promising, with modest evidence

Peptides are short chains of amino acids, the building blocks of proteins. In skincare they are usually grouped by what they are designed to do:

• Signal peptides are meant to encourage skin cells to produce structural proteins such as collagen.
• Carrier peptides deliver trace elements; copper peptides are the most familiar example.
• Neurotransmitter-inhibiting peptides are marketed to soften the look of expression lines.
• Enzyme-inhibiting peptides aim to slow the breakdown of skin proteins.

The honest picture: lab findings are encouraging, but strong human evidence for topical peptides is thin. A 2026 systematic review and meta-analysis in Frontiers in Medicine pooled 19 randomized controlled trials with 1,341 participants. Only two of those trials tested topical peptides, and the topical results showed a small, non-significant effect on wrinkles. The authors described the evidence base as limited, with high variability between studies.

That does not mean peptide products are useless. Many are pleasant, well-tolerated moisturizers and serums. It means expectations should be realistic: think of peptides as a gentle supporting ingredient, not a substitute for better-studied options. Explore peptide skincare if you enjoy them.

What about collagen creams?

Collagen in a cream is a large protein. Very large molecules generally cannot pass passively through the outer skin layer, so topical collagen is better understood as a moisturizing, film-forming ingredient that helps skin feel smooth and hydrated, not as a way to replace the collagen in deeper skin. Browse collagen skincare with that in mind.

PDRN: interesting science, limited topical evidence

PDRN (polydeoxyribonucleotide) is a mixture of DNA fragments, traditionally purified from salmon or trout sperm. A review of PDRN in wound healing explains that it is thought to act partly through adenosine A2A receptors and by supplying building blocks that cells can reuse. Most of the clinical research involves PDRN given by injection in medical settings, often in small groups of patients, rather than creams or serums.

For skincare, the biggest question is whether PDRN can get into the skin at all. A 2025 study in Pharmaceutics notes that PDRN fragments are far too large to pass passively through the outer skin layer, that their negative charge may further limit uptake, and concludes that unmodified PDRN is suboptimal as a cosmetic active. The researchers tested a modified form, but its human trial was small and short.

So the fair summary is this: PDRN serums are popular, especially in K-beauty, and are generally gentle, but evidence that topical PDRN delivers the results associated with injected treatments is limited. Do not expect a cream to replicate an in-clinic procedure. If you want to try it, look at PDRN skincare as an experiment rather than a must-have, and patch test first since many formulas are fish-derived.

Combining with retinol and vitamin C

All three ingredients are generally easy to pair with other actives, which is part of their appeal.

• Retinol: use it at night, starting every other night and building up slowly. A ceramide moisturizer applied afterward can help with the dryness retinol often causes. Our guide to retinol vs retinoids in Canada covers strengths and how to start.
• Vitamin C: often used in the morning after cleansing. A peptide or ceramide moisturizer can follow it. Many formulators suggest keeping copper peptides and pure L-ascorbic acid in separate routines (for example, vitamin C in the morning and copper peptides at night) because the two can react; it is a cautious, easy habit. See our niacinamide, hyaluronic acid and vitamin C guide.
• Keep it simple. Stacking many serums increases the chance of irritation. One active serum per routine, followed by a supportive moisturizer, is plenty for most people. You can compare face serums by ingredient.

Retinoids are not recommended during pregnancy. If you are pregnant, breastfeeding or using prescription skin treatments, check with a pharmacist, doctor or dermatologist before adding new actives.

Barrier care for dry Canadian winters

The Canadian Dermatology Association identifies cold weather as the most common cause of dry skin, because outdoor humidity drops and indoor heating pushes out hot, dry air. Its advice includes short, warm showers, gentle fragrance-free cleansers, moisturizer applied right after washing, creams or ointments instead of lotions, and a humidifier at home.

A barrier-friendly winter routine might look like this:

1. Gentle cleanser, lukewarm water.
2. One serum: vitamin C in the morning, or a peptide or PDRN serum if you enjoy it.
3. A ceramide cream, applied to slightly damp skin.
4. At night, retinol on alternate nights, followed by the same ceramide cream.
5. If skin stings, flakes or turns red, pause retinol and exfoliants and keep only cleanser and moisturizer until it settles.

Quick summary

• Ceramides: well supported for hydration and barrier support. A winter essential.
• Peptides: gentle and widely tolerated, but topical evidence is modest. Keep expectations realistic.
• Collagen creams: moisturizing, not a collagen replacement.
• PDRN: most research uses injections; topical evidence is limited and penetration is a real hurdle.
• Use retinol at night, vitamin C in the morning, and finish with a ceramide moisturizer.
• Patch test new products and ask a professional if you have a skin condition.

Frequently asked questions

Do ceramide moisturizers actually help dry skin?

Research reviews show that ceramide-containing formulations can reduce water loss and improve hydration compared with placebo, which makes them a sensible choice for dry winter skin.

Do topical peptides reduce wrinkles?

Evidence is modest. A 2026 meta-analysis found only two topical peptide trials among 19 studies, with a small, non-significant effect on wrinkles, so expectations should be realistic.

What is PDRN in skincare?

PDRN is a mixture of DNA fragments, traditionally purified from salmon or trout sperm. Most clinical research uses injections, and evidence for topical PDRN in creams and serums is limited.

Can I use peptides with retinol and vitamin C?

Generally yes. A common approach is vitamin C in the morning and retinol at night, with a peptide or ceramide moisturizer after either; many formulators suggest keeping copper peptides and pure vitamin C in separate routines.

Does collagen cream add collagen to my skin?

Collagen is a large protein that generally cannot pass passively through the outer skin layer, so collagen creams are better seen as moisturizing rather than a way to replace collagen in deeper skin.