What are Peptides?

Peptides are short chains of amino acids - the same building blocks that make up the proteins in your skin. The most important of these proteins is collagen, which gives skin its structure, firmness, and bounce. As we age, our body produces less collagen, skin becomes thinner, less elastic, and fine lines begin to form.

This is where peptides come in. When applied topically, certain peptides act as signalling molecules - they communicate with your skin cells, essentially mimicking the signals that tell your body to produce more collagen, repair damage, or retain moisture. They don't add collagen directly (collagen molecules are too large to penetrate the skin). Instead, they trigger the biological processes that produce it from within.

Think of peptides as a message written in your skin's own language. Your skin reads it, and responds.

Why Peptides Are Different From Other Actives

Most skincare actives work by doing something dramatic to the skin - exfoliating, brightening, or accelerating cell turnover. Peptides work differently. They work with your skin's own biology, supporting and amplifying processes that already exist but slow down with age. This is why they're:

• Extremely well-tolerated — no irritation, no purging, no downtime
• Effective across all skin types — from sensitive to oily to mature
• Versatile partners — they enhance the results of almost every other ingredient they're paired with
• Cumulative in effect — results build over consistent use, rather than appearing dramatically overnight

Not all peptides are the same. The term covers a wide range of molecules, each with a different mechanism and a different target in the skin. Here are the main types you'll find in INKEY List formulations:

Signal Peptides

These tell the skin to produce more collagen or elastin. Matrixyl 3000™ - found in our Hyaluronic Acid Serum and Caffeine Eye Cream - is one of the most extensively researched signal peptide complexes in skincare. It contains Palmitoyl Tripeptide-1 and Palmitoyl Tetrapeptide-7, which work together to stimulate collagen production and support skin repair.

Carrier Peptides

These deliver trace minerals or other actives deep into the skin to support collagen synthesis and wound repair.

Enzyme-Inhibitor Peptides

These slow down the enzymes that break down collagen. Royal Epigen P5™ - in our Peptide Moisturiser - works partly through this mechanism, delaying the degradation of skin cells and helping to even skin tone at the same time.

Growth Factor Peptides

Epitensive™ EGF (Epidermal Growth Factor), found in our 15% Vitamin C + EGF Serum, is a plant-derived signal peptide that communicates with skin cells to stimulate renewal and regeneration - improving elasticity and supporting a firmer-looking complexion over time.

Structural / Volume Peptides

Tripeptide Complex - in our Tripeptide Plumping Lip Balm - works at the surface of the lips to boost volume and definition by stimulating the skin's own structural mechanisms. This is how you get real plumping without tingle, irritation, or the swelling tricks used by traditional lip plumpers.

Firmer, More Elastic Skin

The most well-established benefit of peptides is their ability to support collagen synthesis. Collagen is the structural protein responsible for skin's firmness and bounce. When signal peptides like Matrixyl 3000™ communicate with fibroblasts (the skin cells that produce collagen), they help restore the skin's structural integrity - resulting in visibly firmer, more elastic skin over consistent use.

In our 4-week independent consumer study, 82% of users agreed their skin felt firmer, smoother and more elastic after using the Hyaluronic Acid Serum (which includes Matrixyl 3000™ Peptide alongside 2% Multi-Molecular Hyaluronic Acid).

Reduces the Appearance of Fine Lines and Wrinkles

Fine lines form where collagen has thinned and the skin has lost its structural support. By stimulating collagen production from within, peptides address the root cause rather than just filling in the appearance of lines. This is why peptide-based products deliver results that improve over time - rather than simply offering a surface-level plumping effect.

Strengthens the Skin's Moisture Barrier

Certain peptides - including the barrier-supporting Acetyl Hexapeptide-37 in our Peptide Moisturiser - help reinforce the skin's natural moisture barrier. A stronger barrier means better hydration retention, less sensitivity, and more resilient skin. This is one reason peptides are particularly valuable for skin that's dehydrated, stressed, or showing the early signs of environmental damage.

Deep, Lasting Hydration

Unlike simple humectants that sit on the surface and draw in water, peptides that target barrier function help lock hydration into the skin's deeper layers. Combined with other hydrating actives like Hyaluronic Acid, peptides create a multi-layer hydration system that delivers both immediate and long-term results.

Brightens and Evens Skin Tone

Royal Epigen P5™ - the hero peptide in our Peptide Moisturiser - works on an epigenetic level to delay the ageing of skin cells and help even skin tone over time. When combined with antioxidants like Vitamin C (as in our 15% Vitamin C + EGF Serum), peptides amplify the brightening process through different complementary pathways.

Plumps Lips Naturally

The 6% Tripeptide Complex in our Tripeptide Plumping Lip Balm works at the surface of the lips to visibly increase volume and reduce fine lines - without the tingle or irritation of traditional chemical-based lip plumpers. This is peptide technology applied where it's most visible.

Reduces Under-Eye Puffiness and Firms the Eye Area

The delicate eye area is one of the first places to show signs of fatigue and ageing. Matrixyl 3000™ Peptide in our Caffeine Eye Cream works alongside 0.3% Caffeine to boost collagen production in this thin-skinned area, plumping, firming, and smoothing while Caffeine tackles puffiness directly. 95% of users agreed skin felt instantly smoother and deeply hydrated after use.

Suitable for All Skin Types - Including Sensitive and Pregnant Skin

Peptides are among the most universally tolerated actives in skincare. They cause no irritation, no purging, and no sensitivity. They work equally well on oily, dry, combination, and sensitive skin. Every INKEY List peptide-containing product is also formulated to be safe during pregnancy and breastfeeding.

One of peptides' greatest advantages is how easily they slot into any routine. There's no complicated timing, no waiting periods, and no need to keep them away from other actives.

Where Peptides Sit in Your Routine

Apply peptide products in order of texture - thinnest to thickest - after cleansing. This means:

1. Cleanser
2. Hydrating Serum (e.g. Hyaluronic Acid Serum — applied to damp skin)
3. Treatment Serum (e.g. 15% Vitamin C + EGF Serum)
4. Eye Treatment (e.g. Caffeine Eye Cream)
5. Moisturiser (e.g. Peptide Moisturiser)
6. SPF (AM only)
7. Lip Balm (Tripeptide Plumping Lip Balm — can be applied anytime)

How Much to Use

• Hyaluronic Acid Serum: A pea-sized amount on damp skin — this is your hydration base
• 15% Vitamin C + EGF Serum: A pea-sized amount — wait 60 seconds before the next layer
• Caffeine Eye Cream: A pea-sized amount split between both eyes — pat gently around the orbital bone
• Peptide Moisturiser: A pea-sized amount massaged into face and neck
• Tripeptide Lip Balm: Apply a small amount directly to lips — at least 3x daily for best results

How Often?

All INKEY List peptide products are gentle enough for twice-daily use (AM and PM). For the Tripeptide Lip Balm, the more consistently you apply it, the faster and more pronounced the results - aim for at least 3 applications per day for the full 4-week effect.

Morning vs Evening: Which Is Better?

💡INKEY Tip:Apply your Hyaluronic Acid Serum to skin that's still slightly damp after cleansing. It enhances absorption and primes your skin to get more from every peptide product layered on top.

Peptides and Retinol - A Powerful Combination

Retinol and peptides are often compared, but they work through completely different mechanisms - which makes them an exceptional combination rather than competitors.

• Retinol accelerates cell turnover, targeting the surface renewal of skin for anti-ageing results. It can cause initial irritation and requires careful introduction.
• Peptides work at the signalling level, supporting collagen production and barrier function without any irritation risk.

Used together: Peptides are ideal to use in the AM routine; retinol in the PM. The peptides support barrier repair and hydration, which can reduce any dryness caused by retinol - making the combination particularly effective for those who are new to retinol or have sensitive skin.

Peptides and Vitamin C - Better Together

Vitamin C and peptides address the skin's ageing process from two angles simultaneously:

• Vitamin C neutralises free radicals, inhibits melanin production, and fades dark spots
• Peptides (EGF) stimulate skin cell renewal and support elasticity

Our 15% Vitamin C + EGF Serum combines both in a single formula - 15% Ascorbyl Glucoside for brightening and 1% Epitensive™ EGF for regeneration. In a 4-week consumer trial, 87% of users agreed skin looks brighter, while 84% agreed skin looks healthier and less dull.

Peptides and Hyaluronic Acid - INKEY's Signature Duo

This is the combination at the heart of our bestselling Hyaluronic Acid Serum. The 2% Multi-Molecular Hyaluronic Acid delivers immediate, deep hydration at multiple skin depths, while Matrixyl 3000™ Peptide works on the structural level to support firmer skin over time. Together, they give you instant plumping and long-term collagen support in a single step.

Peptides Ingredient Compatibility Guide

Hyaluronic Acid Serum - £9 | 30ml

The Hydrating Peptide Foundation

The INKEY List's bestselling serum - and the most-reviewed product in the range with over 3,100 five-star reviews - is also a powerful peptide delivery system. The hero is 2% Multi-Molecular Hyaluronic Acid, but it's the addition of Matrixyl 3000™ Peptide that elevates this from a hydration serum to a genuine firming treatment.

The formula:

• 2% Multi-Molecular Hyaluronic Acid — holds up to 1,000x its weight in water, delivering instant hydration at multiple depths of skin
• Matrixyl 3000™ Peptide (Palmitoyl Tetrapeptide-7 + Palmitoyl Tripeptide-1) — one of the most studied signal peptide complexes in skincare. Targets the appearance of fine lines and supports firmer-looking skin over time

Consumer test results (4-week independent study of 22 people under dermatological control):

• 82% agreed skin felt firmer, smoother, and more elastic
• 86% agreed the formula is quick-absorbing, lightweight, and non-tacky
• Clinically proven to deliver instant hydration and reduce water loss

What it targets: Dehydrated skin | Fine lines & wrinkles | Damaged skin barrier

Suitable for: All skin types | Sensitive skin | Pregnancy & breastfeeding | Teen approved

Certifications: Vegan Society Certified | Leaping Bunny Cruelty-Free | Fragrance-Free | Clinically Tested

Awards: Allure Best of Beauty | CEW 2023 Award | Get the Gloss Gold | Glamour

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Caffeine Eye Cream - £10 | 15ml

The Peptide-Powered Eye Awakener

The Caffeine Eye Cream is clinically proven to improve the appearance of puffiness and dark circles from first use — and the peptide in its formula is what separates it from a basic caffeine product. Matrixyl 3000™ Peptide works in the delicate eye area to boost collagen production, plumping and firming the skin where it's thinnest and most vulnerable.

The formula:

• 0.3% Caffeine — a natural antioxidant that tackles the fluid retention behind under-eye puffiness and dark circles
• Matrixyl 3000™ Peptide (Palmitoyl Tetrapeptide-7 + Palmitoyl Tripeptide-1) — boosts collagen production to plump, firm, and smooth the delicate eye area
• Albizia Julibrissin Bark Extract — specifically reduces signs of under-eye fatigue for brighter, more awake-looking eyes

Consumer test results (4-week independent study of 22 people under dermatological and ophthalmological control):

• 95% agree skin feels instantly smoother and deeply hydrated
• 95% agree it's quick-absorbing, lightweight, and does not pill
• Clinically proven to improve puffiness & dark circles from 1st use
• Clinically proven to deliver instant hydration

What it targets: Puffiness | Dark circles

Suitable for: All skin types | Sensitive skin | Pregnancy & breastfeeding

Certifications: Leaping Bunny Cruelty-Free | Fragrance-Free | Clinically Tested | Ophthalmologically Tested

Awards: Get the Gloss Gold | Vogue | Glamour | This Morning

💡 INKEY Tip: Store your Caffeine Eye Cream in the fridge for an extra cooling, depuffing boost on tired mornings.

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15% Vitamin C + EGF Serum - £15 | 30ml

The Brightening + Renewal Peptide Serum

This is where brightening and peptide technology meet. The 15% Vitamin C + EGF Serum uses 15% Ascorbyl Glucoside - a stable, gentle form of Vitamin C - alongside 1% Epitensive™ EGF, a plant-derived Epidermal Growth Factor peptide that signals skin cells to renew and regenerate. The result: a serum that brightens what's already there while encouraging the generation of healthier skin underneath.

The formula:

• 15% Ascorbyl Glucoside — stabilised Vitamin C that converts to active form on contact with skin. Targets melanin production, fades dark spots, provides antioxidant protection
• 1% Epitensive™ EGF (Oligopeptide-1) — plant-derived Epidermal Growth Factor by Lipotrue. A signalling peptide that stimulates skin cell renewal and regeneration, supporting elasticity and firmness over time

Consumer test results (4-week independent consumer trial of 64 people):

• 87% agree skin looks brighter
• 88% saw visible improvement in skin tone and texture
• 84% agree skin looks healthier and less dull

What it targets: Hyperpigmentation | Dull skin | Uneven skin tone

Suitable for: All skin types | Sensitive skin | Pregnancy & breastfeeding

Certifications: Vegan Society Certified | Leaping Bunny Cruelty-Free | Fragrance-Free | Dermatologically Tested

Awards: Glamour | ELLE | Marie Claire | The Independent | Good Housekeeping

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Peptide Moisturiser - £16 | 50ml

The Anti-Ageing Daily Moisturiser

The Peptide Moisturiser is built around two of the most targeted peptide technologies in INKEY's range. Royal Epigen P5™works at an epigenetic level — influencing how skin cells express themselves over time to delay the visible signs of ageing and even skin tone. Diffuporine (Acetyl Hexapeptide-37) supports the skin's moisture barrier from within, helping to maintain hydration and a visibly radiant complexion.

The formula:

• 2% Royal Epigen P5™ (Pentapeptide-48) — an epigenetic peptide that delays the ageing of skin cells and helps even skin tone. Designed to accelerate skin renewal for smoother, more even-looking skin
• 1% Hydrating Peptide Solution (Diffuporine / Acetyl Hexapeptide-37) — targets the skin's moisture barrier to hydrate, improve barrier function, and support a visibly radiant complexion

What it targets: Fine lines & wrinkles | Dry skin | Damaged skin barrier

Suitable for: All skin types | Sensitive skin | Pregnancy & breastfeeding

Certifications: Vegan Society Certified | Leaping Bunny Cruelty-Free | Fragrance-Free | Gluten-Free

Awards: Allure

How to use: AM and PM. After cleansing and hydrating, gently massage a pea-sized amount into face and neck. Follow with SPF in your AM routine.

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Tripeptide Plumping Lip Balm - £11 | 10ml

The Science-Backed Lip Plumper

Most lip plumpers work by irritating the lips into temporary swelling. This one takes the opposite approach - using 6% Tripeptide Complex to naturally stimulate lip volume over time and 2% Ultra Filling Spheres (which deliver Hyaluronic Acid directly into the lip surface) to smooth, hydrate, and plump from within. No tingle. No irritation. Just real, measurable results.

The formula:

• 6% Tripeptide Complex (Palmitoyl Tripeptide-1 + Palmitoyl Tripeptide-38) — visibly increases lip volume and definition over time by targeting the natural structural mechanisms of the lips
• 2% Ultra Filling Spheres — dehydrated Hyaluronic Acid that expands on contact with moisture, delivering immediate plumping and locking in hydration to smooth fine lines on and around the lips

Consumer test results (4-week independent clinical study of 20 people):

• Clinically proven to plump lips by up to 40% in 4 weeks
• Visibly smoothed fine lines on lips in 2 weeks
• 95% felt the balm instantly nourished and hydrated the lips

What it targets: Lip volume | Dry, cracked lips | Fine lines around the mouth

Available in: Clear | Mocha | Pink | Berry

Suitable for: All skin types | Pregnancy & breastfeeding

Certifications: Vegan Society Certified | Leaping Bunny Cruelty-Free | Fragrance-Free | Clinically Tested

Awards: Allure | Glamour | Get the Gloss | Sheerluxe

How to use: Apply a small amount to clean lips at least 3x daily. Use consistently for 4 weeks to see the full volume benefit. Wear alone or layered over lip colour.

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Not All Peptides Do the Same Thing - Specificity Matters

When choosing a peptide product, the most important question isn't "does it contain peptides?" It's: which peptides, at what concentration, and what are they designed to do?

A product labelled "with peptides" could contain a trace amount of a single peptide at a concentration too low to have any meaningful effect. INKEY's approach is the opposite: named peptide complexes at validated concentrations, with a clear explanation of what each one does.

Supporting Ingredients to Look For

The best peptide formulas don't rely on peptides alone. Look for:

• Hyaluronic Acid — immediately hydrates and plumps, amplifying the firming effect of peptides
• Vitamin C (Ascorbyl Glucoside) — brightens and protects, working alongside peptides for a more comprehensive anti-ageing result
• Shea Butter / Emollients — help deliver peptides deeper into the skin in moisturiser formulas
• Squalane — plant-derived barrier support that aids absorption without clogging pores

Format Guide

Are Peptides Safe?

Yes - peptides are one of the most extensively researched and universally well-tolerated categories of skincare ingredients. Because they work by mimicking signals that already exist within the skin's biology, they don't disrupt, irritate, or strip the way stronger actives can.

There is no purging phase. There is no initial irritation period. There is no need to introduce them gradually. You can start using peptide products daily from day one.

Potential Side Effects

There are no established side effects associated with topical peptide use at the concentrations used in skincare. Unlike retinol, AHAs, or high-concentration Vitamin C, peptides do not sensitise, exfoliate, or cause photosensitivity.

Who Should Take Care

• Those using prescription retinoids or active medications: Always check with your GP or dermatologist before adding new skincare actives
• Patch testing: INKEY always recommends patch testing any new product before full-face application — apply a small amount to the inside of your wrist for 24 hours first

Peptides and Pregnancy

All INKEY List peptide-containing products are formulated to be safe during pregnancy and breastfeeding. If you have specific concerns, always consult your midwife or healthcare provider.

Application Tips

Apply in the right order. Thinnest formula first, thickest last. Your Hyaluronic Acid Serum goes on damp skin immediately after cleansing; your Peptide Moisturiser goes on last before SPF.

Don't rush the layering. Wait 60 seconds after applying a serum before applying the next product. This prevents pilling and ensures each ingredient is properly absorbed before the next one is applied.

For the Tripeptide Lip Balm - consistency is everything. The tripeptide complex builds cumulative volume over time. Three or more applications per day, every day, for four weeks is what delivers the clinical result. A once-daily application won't give you the full 40% volume increase.

Apply Caffeine Eye Cream with your ring finger. It applies the least pressure, protecting the delicate orbital area. Pat — never rub — around the eye contour.

Common Mistakes to Avoid

Expecting results in days. Peptides are a long-game ingredient. Hydration and texture improvements come first (within 1–2 weeks); firming and structural changes develop over 4–8 weeks of consistent use. Trust the timeline.

Thinking peptides replace retinol. They don't - they complement it. Retinol accelerates cell turnover; peptides support collagen production and barrier repair. Use both in split AM/PM routines for the most comprehensive anti-ageing approach.

Under-dosing the Lip Balm. Applying once a day won't deliver the clinical result. Three times daily is the minimum for the 4-week transformation.

How Long Until You See Results?

Why Matrixyl 3000™?

Matrixyl 3000™ is one of the best-studied signal peptide complexes available to cosmetic formulators. Its two components - Palmitoyl Tripeptide-1 and Palmitoyl Tetrapeptide-7 - work synergistically to stimulate fibroblasts (the cells responsible for producing collagen) while reducing the inflammation that breaks collagen down. The result is a two-way action: building more collagen while protecting what's already there.

Why Epitensive™ EGF?

EGF (Epidermal Growth Factor) is a protein that occurs naturally in the body and plays a key role in cell signalling - specifically triggering skin cells to renew and regenerate. Our 1% Epitensive™ is sourced from Lipotrue, a biotech ingredient company, and is produced through biotechnology rather than from animal sources. This makes it suitable for vegans and more sustainably produced than many EGF alternatives.

Why Royal Epigen P5™?

Royal Epigen P5™ is an epigenetic peptide - meaning it works at the level of gene expression, influencing how skin cells behave rather than simply providing structural support. At 2% in our Peptide Moisturiser, it helps delay the visible ageing of skin cells and works to even skin tone through a mechanism that's distinct from brightening actives like Vitamin C.

Why 6% Tripeptide Complex?

The Tripeptide Complex in our Lip Balm is formulated at a clinically validated 6% concentration - the level at which it delivers the measured 40% volume increase in the 4-week clinical trial. Lower concentrations would not deliver the same result. This is why concentration specificity matters so much when evaluating any peptide product.

Our Quality Standards

Every INKEY List product is held to the same standards:

• Dermatologically tested
• Fragrance-free
• Vegan Society Certified (where applicable)
• Leaping Bunny Certified
• 100% Recyclable Packaging
• Pregnancy-safe formulations

The Gold Standard Morning Routine (Anti-Ageing + Brightening)

Evening Routine (Repair + Renewal)

Power Combinations

Peptides aren't a trend. They're one of the most scientifically grounded categories in modern skincare, with decades of research behind them and real, measurable results that build with every application. Whether you're just beginning to think about anti-ageing, looking to firm and hydrate dehydrated skin, or wanting to naturally plump your lips without needles or irritation - peptides deliver.

Start with the Hyaluronic Acid Serum at £9 - the most-reviewed product in the INKEY range, and one of the most effective peptide-powered hydration serums available at any price. From there, build your peptide routine product by product, concern by concern.

Apply consistently. Layer intelligently. Trust the process.

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