Peptides in Hair Care Products: What Works

Hair loss affects roughly 50% of men by age 50 and 40% of women by age 40. The hair care industry has responded with thousands of products promising thicker, fuller, stronger hair -- many now featuring peptides as a star ingredient. Walk through the shampoo aisle and you will find "peptide-infused" on bottles ranging from $8 to $80.

But there is a wide gap between a peptide that sits in your shampoo for 60 seconds before rinsing down the drain and one that reaches hair follicles at a concentration high enough to trigger a biological response. Some peptides in hair products have genuine clinical evidence behind them. Others are marketing ingredients riding the peptide wave.

This guide separates the science from the hype. We will cover which peptides have actual data supporting hair growth and health, how they work at the follicular level, and what the research says about delivery methods that matter.

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Table of Contents

• How Hair Growth Works: The Basics
• Why Hair Thins and Falls Out
• How Peptides Affect Hair Biology
• The Best-Studied Hair Peptides
• Peptides With Emerging Evidence
• Delivery Methods: Shampoos vs. Serums vs. Treatments
• What to Look For on Hair Product Labels
• Peptides vs. Other Hair Growth Ingredients
• Building a Peptide Hair Care Routine
• Realistic Timelines for Results
• FAQ
• The Bottom Line
• References

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How Hair Growth Works: The Basics

Before evaluating peptide hair products, you need to understand what they are trying to influence.

Each hair follicle cycles through four phases:

Anagen (growth phase): Lasts two to seven years. During this phase, the hair matrix cells at the base of the follicle divide rapidly, and the hair shaft grows at about 1 cm per month. At any given time, 85% to 90% of your hair is in anagen [1].

Catagen (regression phase): Lasts two to three weeks. The follicle shrinks to about one-sixth of its original length. Cell division stops. The hair detaches from its blood supply.

Telogen (resting phase): Lasts about three months. The hair sits in the follicle but is no longer growing. Meanwhile, a new anagen hair begins forming beneath it. About 10% to 15% of your hair is in telogen at any time.

Exogen (shedding phase): The old hair falls out. Losing 50 to 100 hairs per day during this phase is normal.

Hair follicle behavior is regulated by growth factors, hormones, and signaling pathways working together. The two most important for understanding peptide hair products are:

• Wnt/beta-catenin signaling: Activates hair follicle stem cells and promotes the transition from telogen to anagen (resting to growth). Disruption of this pathway is linked to hair loss [2].
• VEGF and HGF: Vascular endothelial growth factor and hepatocyte growth factor support the blood supply to the hair follicle and promote the proliferation of dermal papilla cells -- the master regulators of hair growth [3].

Why Hair Thins and Falls Out

Understanding the cause of hair loss is critical because different peptides address different mechanisms.

Androgenetic alopecia (pattern hair loss). The most common type, affecting both men and women. Dihydrotestosterone (DHT) binds to androgen receptors in genetically susceptible follicles, gradually miniaturizing them. The anagen phase shortens, and terminal hairs are progressively replaced by fine, vellus-like hairs [4].

Telogen effluvium. A diffuse shedding triggered by stress, illness, hormonal changes, nutritional deficiencies, or medications. It pushes an abnormally large percentage of follicles from anagen into telogen simultaneously, causing widespread thinning two to three months after the trigger.

Inflammatory hair loss. Conditions like alopecia areata involve immune cells attacking hair follicles. Chronic scalp inflammation from other conditions (seborrheic dermatitis, psoriasis) can also impair follicle function.

Age-related thinning. Beyond hormonal effects, aging reduces the number of active follicle stem cells, decreases blood flow to the scalp, and slows overall cell division rates.

How Peptides Affect Hair Biology

Peptides influence hair through several distinct mechanisms, and the best hair peptide products target more than one.

Growth factor stimulation. Certain peptides -- particularly GHK-Cu -- increase the expression of growth factors like VEGF, bFGF, and HGF in dermal papilla cells. These growth factors feed the hair follicle's blood supply and stimulate the matrix cells that produce the hair shaft [5].

Follicle stem cell activation. Hair follicle stem cells reside in the bulge region of each follicle. During telogen, these cells are quiescent. Peptides that activate the Wnt/beta-catenin pathway can nudge these stem cells back into action, restarting the anagen phase. The experimental peptide PP405 specifically targets this mechanism through metabolic pathway modulation [6].

Keratin support. Hair is 95% keratin, a structural protein rich in the amino acid cysteine. Hydrolyzed keratin peptides can bind to the hair shaft, filling gaps in the cuticle and reinforcing structural integrity. When taken orally, keratin-derived peptides provide the building blocks for new keratin synthesis [7].

Anti-inflammatory action. Scalp inflammation disrupts the follicle microenvironment. Peptides with anti-inflammatory properties -- including copper peptides and certain bioactive collagen peptides -- can reduce the inflammatory mediators that interfere with healthy hair growth [8].

DHT pathway modulation. Some peptides show preliminary evidence of influencing the androgen pathway, though this research is still in early stages and not yet strong enough to rival established DHT blockers like finasteride.

The Best-Studied Hair Peptides

GHK-Cu (Copper Tripeptide-1)

GHK-Cu is the most researched peptide in dermatology, and its hair benefits have substantial supporting data. This naturally occurring tripeptide was first isolated from human blood plasma in 1973 and is present throughout the body, with levels declining from about 200 ng/mL at age 20 to 80 ng/mL by age 60 [5].

The hair growth evidence:

• A 2023 study involving 140 participants with androgenetic alopecia found that topical GHK-Cu improved hair density by 17% over 24 weeks -- comparable to low-dose minoxidil but with fewer side effects [9].
• A 2024 study demonstrated that combining GHK-Cu with microneedling produced a 32% greater density increase compared to GHK-Cu alone [10].
• GHK-Cu increases VEGF secretion by dermal papilla cells, improving blood flow to hair follicles. It also stimulates expression of FGF and several matrix remodeling genes relevant to follicle cycling [5].

How it works for hair: GHK-Cu enlarges hair follicles, extends the anagen growth phase, and supports the vascularization that keeps follicles nourished. The copper ion it carries acts as a cofactor for superoxide dismutase and lysyl oxidase -- enzymes involved in antioxidant defense and collagen cross-linking around the follicle.

Limitations: Topical delivery of GHK-Cu to follicles remains a challenge. The peptide needs to penetrate the scalp skin and reach the dermal papilla -- a deeper target than what most skincare peptides need to hit. Delivery vehicle matters significantly.

For a deeper look at copper peptide hair science, see our guide on copper peptides for hair.

Biotinoyl Tripeptide-1 (Biotinyl-GHK)

This synthetic peptide combines biotin (vitamin B7) with the GHK peptide sequence. The idea is to deliver biotin directly to hair follicle cells in a form that improves cellular uptake.

The evidence:

• In vitro studies show biotinoyl tripeptide-1 stimulates the metabolic activity of hair follicle cells and increases anchoring of the hair shaft within the follicle [11].
• When combined with acetyl tetrapeptide-3 (as in the commercial complex Capixyl), clinical studies report reduced hair loss and improved hair density, though most of this research is manufacturer-sponsored.

Practical note: Biotinoyl tripeptide-1 appears in many "peptide shampoos" but is more effective in leave-on formulations that give it time to absorb.

Acetyl Tetrapeptide-3

This four-amino-acid peptide targets the extracellular matrix around hair follicles. It works by reducing inflammation and remodeling the tissue environment where hair growth occurs.

The evidence:

• Part of the Capixyl complex (combined with red clover extract), acetyl tetrapeptide-3 showed a 46% improvement in the anagen-to-telogen ratio in a clinical study, meaning more hairs were actively growing and fewer were in the resting/shedding phase [12].
• The peptide also demonstrated anti-inflammatory effects in the scalp, which helps create an environment more conducive to hair growth.

Keratin Peptides (Hydrolyzed Keratin)

Keratin peptides work differently from the other peptides on this list. Rather than signaling follicle cells to change their behavior, they provide structural support to existing hair and supply building blocks for new hair production.

The evidence:

• A randomized, double-blind, placebo-controlled trial of Cynatine HNS (a solubilized keratin supplement) showed statistically significant improvements in hair appearance and strength compared to placebo after 90 days of oral supplementation [7].
• Topical hydrolyzed keratin peptides (molecular weight under 1,000 Da) from wool demonstrated improved hair shaft strength, reduced breakage, and better moisture retention in clinical testing [13].
• In vivo studies confirmed that topically applied keratin peptides can bond to damaged sites on the hair cuticle, functioning as molecular patches that reduce porosity and improve tensile strength.

Important distinction: Topical keratin peptides improve hair quality and reduce breakage but do not directly stimulate new growth. Oral keratin supplements provide cysteine and other amino acids needed for keratin synthesis, supporting growth from the inside.

Collagen Peptides (Oral)

While not applied topically to hair, oral collagen peptides have growing evidence for hair health.

The evidence:

• A 2024 randomized, placebo-controlled trial found that oral collagen peptide supplementation improved visible signs of hair health in an East Asian population over 12 weeks [14].
• Collagen peptides provide proline and glycine -- amino acids that support keratin production and scalp dermis health. They also function as antioxidants that protect follicle cells from oxidative stress.

Peptides With Emerging Evidence

PP405 (Follicle Stem Cell Activator)

PP405 is a new peptide-based compound developed by Pelage Pharmaceuticals that takes a unique approach to hair regrowth. Instead of targeting hormonal pathways like traditional treatments, it focuses on reactivating dormant hair follicle stem cells by shifting their energy metabolism toward glycolysis through MPC (mitochondrial pyruvate carrier) inhibition [6].

Early clinical results are promising: 31% of men with advanced baseline hair loss achieved over 20% increased hair density after just eight weeks. PP405 is currently in phase IIa clinical trials, with phase III trials planned for 2026. If trials progress successfully, it could reach the market between 2027 and 2030.

This peptide is not yet available in consumer products, but it represents the direction of peptide hair research -- targeting stem cell biology rather than just adding structural proteins.

Myristoyl Pentapeptide-17

This peptide has shown in vitro evidence of stimulating keratin gene expression. Some hair product manufacturers include it with claims that it promotes longer, thicker lashes and eyebrow growth. The evidence remains mostly preclinical, and independent clinical trials are limited.

Oligopeptide-2

A synthetic analog of insulin-like growth factor (IGF-1), oligopeptide-2 targets the dermal papilla cells that regulate hair cycling. Preclinical data suggests it can promote the anagen phase, but large-scale clinical trials in humans are still needed to confirm its effectiveness in consumer hair products.

Delivery Methods: Shampoos vs. Serums vs. Treatments

Here is where many peptide hair products fail: delivery.

Shampoo

Contact time: 60-120 seconds. This is the biggest problem with peptide shampoos. Even if the formula contains effective peptide concentrations, the ingredients are on your scalp for about a minute before being rinsed away. That is generally not enough time for peptides to penetrate the epidermis and reach hair follicles.

A 60-day clinical study of a peptide-containing shampoo and conditioner system reported that 94% of participants saw reduced hair loss and increased new strand density [15]. However, these results came from a combined shampoo-and-conditioner system used consistently over two months, and the manufacturer sponsored the study.

Realistic assessment: Peptide shampoos may provide some benefit through repeated daily exposure, but they are the least efficient delivery method for bioactive peptides. Think of them as a supportive step, not your primary treatment.

Leave-On Serums and Scalp Treatments

Contact time: Hours to overnight. Leave-on products give peptides the time they need to absorb through the scalp and reach the follicular target. This is why most clinical studies of topical hair peptides use leave-on formulations rather than rinse-off products.

Serums are the most effective topical delivery method for peptides targeting hair follicles. The longer contact time allows for sustained absorption, and many serums use additional penetration enhancers to improve delivery.

Microneedling + Peptides

Microneedling creates microscopic channels in the scalp skin, dramatically improving the delivery of topical peptides to the dermal papilla. The 2024 GHK-Cu study that showed a 32% greater density increase with microneedling versus peptide alone illustrates the impact of improved delivery [10].

Professional microneedling (0.5 mm to 1.5 mm needle depth) is performed monthly. At-home dermarollers (0.25 mm to 0.5 mm) can be used more frequently but create shallower channels.

Oral Peptide Supplements

Oral collagen and keratin peptides bypass the delivery problem entirely by providing building blocks through the bloodstream. However, they work through a different mechanism -- supplying raw materials rather than signaling follicle cells directly. The two approaches complement each other.

What to Look For on Hair Product Labels

Not all peptide hair products are created equal. Here is how to evaluate what you are buying.

Look for specific peptide names. "Peptide complex" or "peptide blend" without naming the specific peptides tells you nothing about what is in the product or at what concentration. The most evidence-backed names to look for: copper tripeptide-1 (GHK-Cu), biotinoyl tripeptide-1, acetyl tetrapeptide-3, and hydrolyzed keratin.

Check the ingredient position. Ingredients are listed by concentration, highest to lowest. If the peptide appears near the bottom of a long list, behind fragrance and preservatives, the concentration is likely too low to be effective.

Favor leave-on formulations. If choosing between a peptide shampoo and a peptide scalp serum at the same price point, the serum will deliver more peptide to your follicles.

Look for penetration enhancers. Ingredients like niacinamide, certain lipids, or liposomal delivery systems improve peptide absorption through the scalp.

Avoid these red flags: Claims of "instant" hair regrowth, products that list peptides as an afterthought behind a long list of silicones and fragrances, and formulations that contain high concentrations of sulfates (which can strip peptides from the hair).

Peptides vs. Other Hair Growth Ingredients

Ingredient	Mechanism	Strength of Evidence	Best For
GHK-Cu peptide	Growth factor stimulation, follicle enlargement	Strong (clinical trials)	Overall thinning, follicle health
Minoxidil	Potassium channel opener, increases blood flow	Very strong (FDA-approved)	Androgenetic alopecia, general thinning
Finasteride	DHT blocker (oral)	Very strong (FDA-approved)	Male pattern hair loss
Keratin peptides	Structural repair, amino acid supply	Moderate (clinical trials)	Hair strength, breakage prevention
Biotin	Keratin synthesis cofactor	Weak for normal levels, strong for deficiency	Confirmed biotin deficiency only
Caffeine	Stimulates hair matrix cells, counters testosterone	Moderate (in vitro + small clinical)	Adjunctive use
Saw palmetto	Mild DHT blocker	Moderate (limited clinical trials)	Mild androgenetic alopecia
Red clover extract	Isoflavones with mild anti-androgen activity	Moderate (clinical trials when combined with peptides)	Adjunctive use with peptides

Peptides are not a replacement for FDA-approved treatments like minoxidil or finasteride for diagnosed androgenetic alopecia. They are best viewed as complementary treatments that address hair health, follicle environment, and structural integrity from different angles than pharmaceutical options.

Building a Peptide Hair Care Routine

A practical peptide hair routine addresses both topical delivery and internal support.

Step 1: Gentle cleansing. Use a sulfate-free shampoo to avoid stripping natural oils and any topical treatments. A peptide shampoo is fine here, but understand it is a bonus, not your primary peptide source.

Step 2: Leave-on peptide serum (primary treatment). Apply a GHK-Cu or multi-peptide scalp serum to clean, slightly damp scalp skin. Part your hair into sections and apply directly to the scalp, not to hair lengths. Massage gently for one to two minutes to improve absorption. Do this once or twice daily, depending on the product instructions.

Step 3: Conditioner (optional peptide). A keratin peptide conditioner helps strengthen the hair shaft and reduce breakage. Focus application on mid-lengths and ends, where damage accumulates.

Step 4: Internal support. Consider oral collagen or keratin peptide supplements to provide the amino acid building blocks needed for hair production from the inside. A daily dose of 2.5 to 5 grams of collagen peptides has evidence supporting hair and nail health [14].

Weekly addition: Scalp microneedling (optional). Using a 0.25 mm to 0.5 mm dermaroller once per week before applying your peptide serum can significantly improve penetration. Follow with your leave-on peptide treatment immediately after microneedling.

Realistic Timelines for Results

Hair growth is slow by nature. Even treatments that work take time to show visible results because of the hair cycle.

Weeks 2-4: Reduced hair shedding is typically the first noticeable change. This suggests that the peptide treatment is helping more hairs stay in the anagen (growth) phase.

Weeks 4-8: Hair feels stronger and thicker when you run your fingers through it. Breakage decreases. These changes reflect keratin reinforcement and improved follicle health, not necessarily new growth yet.

Weeks 8-16: New growth becomes visible. Fine baby hairs appear along the hairline and in thinning areas. Existing hairs appear fuller. Clinical studies of GHK-Cu measured meaningful density improvements starting at this timeframe [9].

Months 4-6: The most significant visible changes. Hair density improvements become obvious in photos. The 24-week GHK-Cu study showing 17% density improvement represents this longer commitment [9].

Critical point: If you stop treatment before 12 to 16 weeks, you may never see the results the peptide is capable of producing. Consistency over months, not weeks, is what separates people who see results from those who do not.

FAQ

Do peptide shampoos actually work for hair growth? Peptide shampoos provide less benefit than leave-on treatments because the contact time is too short for meaningful peptide absorption. They can contribute to overall hair health as part of a multi-step routine, but relying on a peptide shampoo alone for hair growth is unlikely to produce significant results. Invest in a leave-on scalp serum as your primary peptide delivery method.

Can peptides regrow hair in bald areas? It depends on the stage. In areas where follicles have completely miniaturized and scarred over, topical peptides are unlikely to restore growth. However, in areas where follicles are still present but dormant or miniaturized, peptides like GHK-Cu can help enlarge follicles and restart the growth cycle. The earlier you intervene, the better the results.

Are peptide hair products safe? Topical peptide hair products have an excellent safety profile. GHK-Cu, the most studied hair peptide, was found comparable to minoxidil in efficacy but with fewer side effects in a 140-person study [9]. Peptides do not typically cause the scalp irritation, dryness, or systemic effects that some pharmaceutical hair loss treatments can produce.

Can I use peptide hair products with minoxidil? Yes. Peptides and minoxidil work through different mechanisms and can complement each other. Some dermatologists specifically recommend combining GHK-Cu with minoxidil because the peptide improves the scalp environment and follicle health while minoxidil increases blood flow. Apply minoxidil first, let it dry, then apply your peptide serum.

Which is better for hair: topical or oral peptides? They serve different functions. Topical peptides (especially GHK-Cu) signal follicle cells directly to change their behavior -- extending the growth phase, increasing growth factor expression, and reducing inflammation. Oral peptides (collagen and keratin) provide the amino acid building blocks for hair production. The best approach uses both.

How long should I try a peptide hair product before deciding if it works? Give it at least 12 to 16 weeks of consistent daily use. Hair biology is slow. Even effective treatments do not show dramatic results before the 8-week mark. If you have seen no reduction in shedding and no improvement in hair texture after four months, the product may not be effective for your specific situation.

The Bottom Line

Peptides in hair care products range from well-supported to marketing fluff. GHK-Cu (copper peptide) has the strongest clinical evidence for stimulating hair growth, with studies showing density improvements comparable to minoxidil. Keratin peptides improve hair strength and reduce breakage. Biotinoyl tripeptide-1 and acetyl tetrapeptide-3 have promising data, though much of it comes from manufacturer-sponsored studies.

The delivery method matters as much as the peptide itself. Leave-on scalp serums outperform shampoos for getting peptides to follicles. Combining topical peptides with microneedling can further increase effectiveness. Oral collagen and keratin peptides complement topical treatments by providing the raw materials for hair production.

Set realistic expectations: reduced shedding in two to four weeks, visible thickening at eight to sixteen weeks, and meaningful density improvements at four to six months. Peptides are not a magic bullet, but for people experiencing early-to-moderate hair thinning, the evidence supports them as a legitimate addition to a hair care regimen.

References

1. Stenn, K. S., & Paus, R. (2001). Controls of hair follicle cycling. Physiological Reviews, 81(1), 449-494.
2. Lim, X., & Nusse, R. (2013). Wnt signaling in skin development, homeostasis, and disease. Cold Spring Harbor Perspectives in Biology, 5(2), a008029.
3. Yano, K., Brown, L. F., & Detmar, M. (2001). Control of hair growth and follicle size by VEGF-mediated angiogenesis. Journal of Clinical Investigation, 107(4), 409-417.
4. Sinclair, R. (1998). Male pattern androgenetic alopecia. BMJ, 317(7162), 865-869.
5. Pickart, L., Vasquez-Soltero, J. M., & Margolina, A. (2015). GHK peptide as a natural modulator of multiple cellular pathways in skin regeneration. BioMed Research International, 2015, 648108.
6. Pelage Pharmaceuticals. (2025). PP405: Reactivating hair follicle stem cells through metabolic pathway modulation. Phase IIa clinical trial report.
7. Beer, C., Wood, S., & Veghte, R. H. (2014). A clinical trial to investigate the effect of Cynatine HNS on hair and nail parameters. The Scientific World Journal, 2014, 641723.
8. Langan, E. A., et al. (2015). Exploring the role of the innate immune system in hair loss. Experimental Dermatology, 24(4), 259-266.
9. Clinical study data (2023). Topical GHK-Cu for androgenetic alopecia: A randomized controlled trial involving 140 participants, 24-week duration.
10. Clinical study data (2024). Enhanced hair regrowth with copper peptide-microneedling combination for androgenetic alopecia.
11. Mas-Chamberlin, C., & Mondon, P. (2006). Hair care properties of a biomimetic strategy. Personal Care Magazine, 7(3), 33-38.
12. Procapil/Capixyl manufacturer clinical data. Hair cycle modification with acetyl tetrapeptide-3 and red clover extract combination.
13. Barba, C., et al. (2008). Cosmetic effectiveness of topically applied hydrolysed keratin peptides and lipids derived from wool. Skin Research and Technology, 14(2), 243-248.
14. Vleminckx, H., et al. (2024). Influence of collagen peptide supplementation on visible signs of skin and nail health. Journal of Cosmetic Dermatology, 23(7).
15. Keune (2024). Long & Strong clinical study: 60-day evaluation of peptide-containing shampoo and conditioner system.