Why Peptides Belong Inside Your Skin, Not Just On Top Of It
Erra Skin | Published 2026 | 7 min read
Most skincare products sit on the surface of your skin and work from the outside in. Cleansers, moisturisers, even most serums. They do their job at the level of the epidermis and rely on gradual absorption to reach deeper layers.
Peptides are different. Not because they are more potent than other ingredients, but because of where they need to be to work properly. Peptides are cell-signalling molecules. Their job is to communicate with the deeper layers of the dermis, where collagen and elastin are produced. Applied topically, even a well-formulated peptide serum faces a fundamental limitation: the skin's barrier is designed to keep things out.
This is the problem that the Erra Skin Peptide Infusion Complex was formulated to solve. Not just a serum to apply after treatment, but one designed to be delivered through micro-channels directly into the dermis, at the moment the skin is most receptive. The difference between a peptide sitting on the skin and a peptide delivered beneath it is the difference between a message sent and a message received.
The skin’s barrier is designed to keep things out. Micro-infusion creates a window. The serum is formulated to make the most of it.
What Peptides Actually Do
Peptides are short chains of amino acids, the building blocks of proteins. In skin, the proteins that matter most are collagen and elastin. Collagen provides structure and firmness. Elastin provides the bounce and resilience that keeps skin looking lifted rather than slack.
As skin ages, collagen and elastin production naturally slows. The skin becomes thinner, less firm, and slower to repair itself. This is not a sudden change. It is a gradual decline that accelerates from the mid-thirties onward, and it shows up as dullness, fine lines, loss of texture, and a general flatness that no moisturiser quite addresses.
Peptides work by signalling the skin to produce more collagen and elastin. Different peptides target different stages of this process. Some mimic the fragments of collagen that the skin naturally produces during repair, triggering a renewal response. Others work on the neuromuscular signals that cause expression lines to form. Others still focus on the structural proteins that keep the skin matrix dense and resilient.
The science behind peptides is well established. What has historically limited their effectiveness in topical skincare is not the ingredient itself, but delivery. Getting a peptide molecule past the skin’s barrier and into the dermis, where it can actually signal collagen production, is the challenge that most peptide serums only partially solve.
THE DELIVERY PROBLEM: The outermost layer of skin, the stratum corneum, acts as a selective barrier. It allows small molecules through more readily than large ones. Peptide molecules vary in size, and many of the most effective ones are too large to penetrate the barrier in meaningful concentrations through topical application alone. Micro-infusion bypasses this entirely.
Why Micro-Infusion Changes the Equation
When the Erra Skin device creates micro-channels in the skin, it temporarily opens direct pathways into the dermis. These are atraumatic channels, meaning the tissue is gently displaced rather than damaged. The channels remain open long enough for active ingredients to be delivered precisely where they need to go.
This is why the serum is delivered simultaneously with the treatment, not applied before or after. The Peptide Infusion Complex is drawn into the micro-channels as they form, carried directly into the dermis at the moment the skin’s renewal response is being triggered. The peptides arrive at the site of collagen production, not the surface above it.
The result is a significant increase in bioavailability. The same ingredients that would sit largely on the skin’s surface in a standard serum are now working at the depth where they can make a measurable difference. This is not a marginal improvement. It is a fundamental change in how the ingredients function.
Peptides delivered to the dermis are doing the job they were designed to do. Peptides sitting on the surface are waiting for a door that may never open.
The Three Peptides in the Erra Skin Formula
The Peptide Infusion Complex contains three clinically recognised peptides, each chosen for a specific role in the skin renewal process. Together they address firmness, fine lines, and structural skin quality from three different angles.
Replexium
Acetyl Dipeptide-1 Cetyl Ester
ROLE: A biomimetic peptide that targets skin firmness and density by supporting the skin’s structural matrix. Replexium works at the level of the dermal-epidermal junction, the boundary layer where the epidermis and dermis meet, helping to reinforce the connections that keep skin looking lifted and resilient.
WHY IT WORKS WITH MICRO-INFUSION: The dermal-epidermal junction is precisely where micro-channels deliver the serum. Replexium is at its most effective when it reaches this layer directly, which topical application alone rarely achieves at meaningful concentrations.
Matrixyl 3000
Palmitoyl Tripeptide-1 and Palmitoyl Tetrapeptide-7
ROLE: One of the most extensively studied peptide complexes in cosmetic science. Matrixyl 3000 works by mimicking the fragments of collagen that the skin produces naturally during repair, signalling fibroblasts to increase collagen and elastin synthesis. Studies have shown it can significantly reduce the appearance of deep wrinkles with consistent use.
WHY IT WORKS WITH MICRO-INFUSION: Fibroblasts, the cells responsible for producing collagen, sit in the dermis. Delivering Matrixyl 3000 through micro-channels places it in direct proximity to these cells, maximising the signalling effect that makes this peptide complex so clinically significant.
Argireline
Acetyl Hexapeptide-3
ROLE: A neuropeptide that targets the repetitive muscle contractions responsible for expression lines. Argireline works by moderating the neuromuscular signals that cause muscles to contract, reducing the depth of dynamic lines over time without the paralysing effect of injectable treatments.
WHY IT WORKS WITH MICRO-INFUSION: Expression lines form at the junction of movement and skin quality. Argireline delivered into the dermis reaches the neuromuscular layer more effectively than surface application, allowing it to work at the depth where expression line formation actually occurs.
The Role of Hyaluronic Acid
Alongside the three peptides, the Peptide Infusion Complex contains hyaluronic acid. Its role in this formula is twofold.
First, hyaluronic acid is a humectant. It draws moisture into the skin and holds it there, providing immediate hydration that complements the longer-term structural work of the peptides. The combination of instant hydration and collagen-signalling activity means the skin responds to treatment both immediately and over time.
Second, hyaluronic acid supports the skin’s recovery environment after micro-infusion. The channels created during treatment close within hours, and well-hydrated skin closes more cleanly and recovers more comfortably. The hyaluronic acid in the formula is calibrated to a molecular weight that works effectively within micro-channels, ensuring it reaches the dermis alongside the peptides rather than sitting above them.
ON MOLECULAR WEIGHT: Hyaluronic acid exists in different molecular weights, and the size of the molecule determines how deeply it penetrates. High molecular weight hyaluronic acid works at the surface, providing a plumping effect. Low molecular weight hyaluronic acid penetrates more deeply. The Peptide Infusion Complex uses a combination calibrated specifically for micro-channel delivery.
Consistency Is What Makes It Work
A single micro-infusion treatment will produce noticeable results. The skin will look brighter and feel smoother within 24 to 48 hours as the renewal response begins. But the transformative effects of consistent peptide delivery, the kind that visibly changes skin firmness, texture, and fine line depth, come from repeated treatments over time.
This is why the Erra Skin treatment frequency is fortnightly. Not weekly, not monthly. Fortnightly gives the skin enough time to complete its renewal cycle between sessions while maintaining the signalling stimulus that drives cumulative collagen production. The peptides compound. Each treatment builds on the last.
The skin does not change quickly. But it does change consistently, and that consistency is what produces results that last rather than results that fade. The Peptide Infusion Complex is formulated for exactly this kind of long-term, compounding skin renewal.
One treatment triggers a response. Twenty treatments build a result. The peptides compound with every session.
Understanding Why Delivery Matters
If you want to understand more about why the method of delivery is as important as the ingredients themselves, the difference between a derma roller and a micro-infusion stamp is the clearest illustration of this principle. The way a treatment interacts with your skin at a tissue level determines not just what results are possible, but whether the ingredients you’re using can reach the depth where they’re effective at all.
We’ve written a full breakdown of the science behind this, including what actually happens to skin tissue with each tool and why atraumatic micro-channels produce a fundamentally different response to ablative roller wounds.
Read next: Derma Roller vs Micro Infusion: Why One Changed My Skin and One Didn’t. Then explore the Erra Skin Micro-Infusion Kit at erraskin.com.
RELATED READING
Derma Roller vs Micro Infusion: Why One Changed My Skin and One Didn’t
Micro Infusion Before and After: My Honest Results After 5 Months