What If Your Serums Aren't Reaching the Cells That Need Them? Here's How Delivery Actually Works

Your skin's outer layer is called the stratum corneum. Think of it as a tightly packed wall of flattened cells held together by lipids (natural fats). Its whole job is to act as a barrier. It keeps moisture in and keeps irritants, bacteria, and foreign substances out.

That's great news for your health. But it creates a real challenge for skincare. Most active ingredients need to pass through this barrier to reach the living cells in the layers below.

The dermis, which sits beneath the outer layers, is where collagen and elastin live. It's where repair cells called fibroblasts do their work. It's where real, lasting skin change actually happens.

The stratum corneum is selective about what gets through. Small, oil-soluble molecules tend to pass more easily. Large, water-loving molecules face a much harder path.

This is why two products with the same active ingredient can deliver very different results. The ingredient matters, but the delivery system matters just as much. You can read more about how your barrier works in our guide to your skin's barrier function.

A delivery system is the method a formulation uses to carry an active ingredient past the skin's barrier and into the layers where it can work. Without a smart delivery system, many actives simply sit on the surface. They may feel good and even offer some surface-level hydration, but they never reach the cells that need them most.

There are a few key delivery approaches used in modern skincare. Liposomal encapsulation wraps active ingredients in tiny fat-based spheres called liposomes. Because these spheres are made from similar materials to your skin's own lipid barrier, they can fuse with it and release their contents deeper in the skin. Peptide carriers attach active molecules to small amino acid chains that help guide them through the barrier. Molecular sizing involves breaking larger molecules into smaller fragments that can physically fit through the barrier's pathways.

Each approach has its strengths depending on the ingredient being delivered. The best formulations match the delivery method to the active ingredient's specific chemistry. This is where expert formulation makes a real difference.

The FutureCode Booster from Dermalogica is built around this exact challenge. Its key actives are chosen not just for what they do, but for how well they can actually reach the cells that need them.

Teprenone is a small, oil-soluble molecule. This matters because oil-soluble ingredients move through the lipid-rich stratum corneum more easily than water-based ones. Teprenone supports the skin's natural repair processes at a cellular level, helping to reduce visible signs of DNA-related damage that builds up over time. Niacinamide (vitamin B3) is water-soluble but small enough to penetrate effectively.

It supports the skin's barrier, helps even skin tone, and works on multiple concerns at once. Acetyl Zingerone is a stabilised form of ginger-derived antioxidant. Antioxidants (molecules that protect cells from oxidative damage) are most useful when they reach living cells. And the acetyl modification helps this ingredient do exactly that.

Helianthus Annuus (Sunflower) Sprout Extract and Rosa Canina Seed Oil (rosehip oil) provide lipid-based support that works with the skin's own barrier chemistry rather than against it. Rosehip oil is rich in linoleic acid, a fatty acid that the skin uses to maintain its barrier structure. When a product contains ingredients the skin recognises, absorption tends to be more efficient. If you're curious about how high-performing serums fit into a complete routine, our article on lifting and restoring with a high-performing serum is worth a read.

Yes, and this is one of the most important things to understand when comparing products. The general rule in skincare science is that molecules under 500 Daltons (a unit used to measure molecular weight) can pass through the stratum corneum more readily. Many popular actives are right at or below this threshold when properly formulated.

Hyaluronic acid is a good example. In its standard form, it's a very large molecule. It sits on the skin's surface and provides surface hydration, which is still useful. But low molecular weight hyaluronic acid fragments are small enough to penetrate deeper, where they can attract and hold moisture within the skin tissue itself.

The ingredient is the same. The size is different. The result is very different too.

This is why reading an ingredient list only tells part of the story. The molecular size, the formulation pH, the presence of penetration enhancers. And the delivery technology all shape how much of an active ingredient actually reaches its target. A product built with delivery science in mind will consistently outperform one that lists impressive actives but hasn't solved the penetration problem.

It does, and this is a practical point that's easy to get wrong. When you layer products, each one creates a film on the skin. If you apply a heavier product first, it can physically block lighter ones from penetrating. The general rule is to go from lightest to heaviest texture, thinnest to thickest consistency.

Serums go on before moisturisers for this reason. They're designed with thin, fast-absorbing formulations that can reach the skin before a heavier cream creates a barrier. Boosters like the FutureCode Booster are typically applied after cleansing and toning, before your main serum or moisturiser. This gives the active ingredients the best chance of reaching the skin before other layers are in place.

pH also plays a role. Some actives work best in an acidic environment. If you apply them after a product that shifts the skin's pH, their effectiveness can drop. This is why some products are designed to be used at specific times or in a specific order. If you've ever wondered whether you're applying your products in the right sequence, our guide on product application order covers this in detail.

This is the honest question underneath all of this. You can have a shelf full of well-reviewed products and still not be getting the results you're after. Sometimes that's a delivery issue. Sometimes it's a compatibility issue. Sometimes it's simply that the routine hasn't been assessed for your specific skin.

A few signs that delivery might be the issue: your skin feels good right after application but the effect doesn't last, you've been consistent for months but haven't seen the changes you expected, or you're reacting to products that seem gentle on paper. These can all point to a mismatch between what's in the bottle and what's actually reaching your cells.

The most useful thing you can do is get a clear picture of what your skin actually needs right now. And whether your current products are formulated to deliver it. That's exactly what the Skin Consultation is designed for. It looks at your skin, your routine, and your goals together, so you're not just guessing. Personalised guidance makes a real difference, and you can learn more about what that looks like through our personalised skincare advice approach.