Peptides for Hair Growth: Which Compounds Have Been Studied for Hair Follicle Biology

Key Takeaways

• Compounds covered: GHK-Cu (copper tripeptide), AHK-Cu (alanyl-histidyl-lysine copper complex), thymosin beta-4 (TB4) / TB-500, collagen peptides (AP peptides, biomimetic peptides), combination peptide formulations
• Goal area: Hair follicle stimulation, anagen induction, androgenetic alopecia support
• Evidence range: Ex vivo human follicle data and combination RCT-adjacent data for GHK-Cu (Pyo et al. 2007; Kuceki et al. 2025); multiple animal studies for thymosin beta-4 (Philp et al. 2004; Philp et al. 2007); RCT for biomimetic peptide formulation (Rinaldi et al., 2019); in vitro pathway data for AP collagen peptides (Lee et al., 2024)
• Regulatory range: GHK-Cu topical and AHK-Cu are cosmetic ingredients (OTC). Injectable GHK-Cu was removed from FDA's interim Category 2 list in April 2026 without placement on Category 1 — not eligible for 503A compounding. TB-500 is not on the FDA 503A bulks list and is not eligible for compounding.
• Key biomarkers for hair growth: Ferritin, vitamin B12, TSH, hs-CRP, IGF-1, SHBG, DHT (if androgenetic alopecia suspected)
• As of April 2026: No peptide drug is FDA-approved for hair loss or hair growth. Injectable GHK-Cu has no legal compounding pathway. TB-500 has no legal compounding pathway. FDA-approved hair loss treatments (minoxidil, finasteride, dutasteride) are not peptides.
• Bottom line: No peptide has completed a large Phase III RCT for hair loss as a primary endpoint. Published evidence is preclinical and early-stage clinical. FDA-approved hair loss drugs are non-peptide small molecules.

Understanding Hair Growth: The Biology of the Follicle Cycle

Hair growth is not continuous. Each follicle cycles independently through three distinct phases: anagen (active growth, lasting 2-7 years for scalp hair), catagen (regression, lasting 2-3 weeks), and telogen (resting and shedding, lasting approximately 3 months). At any given time, roughly 85-90% of scalp follicles are in anagen and 10-15% in telogen. The visible density of hair reflects the ratio of actively growing to resting follicles and the caliber of each hair shaft.

Stenn and Paus published a landmark comprehensive review of hair follicle biology in Physiological Reviews in 2001, detailing the molecular signals controlling follicle growth, stem cell niches within the follicle bulge, and the dermal papilla as the signaling hub that governs follicle cycling. The dermal papilla — a cluster of specialized mesenchymal cells at the base of each follicle — integrates signals that determine whether a follicle enters anagen, how fast it grows, and what diameter hair shaft it produces.

The molecular pathways governing this cycle have been substantially characterized. Wnt/beta-catenin signaling is the primary pathway driving the telogen-to-anagen transition. Hawkshaw and colleagues, in a 2020 British Journal of Dermatology paper, detailed Wnt signalling in telogen-to-anagen transition, showing how follicle stem cells in the bulge region activate when Wnt signals exceed threshold. Lee and colleagues, in a 2024 Experimental Dermatology paper, reported that AP collagen peptides in mouse models promote hair growth via the GSK-3β/β-catenin pathway — linking peptide-mediated signaling to this Wnt activation mechanism in preclinical models.

Uno and Kurata, in a 1993 foundational review in the Journal of Investigative Dermatology, catalogued chemical agents affecting hair growth, establishing the multi-compound landscape that continues to develop today. Peptides can interact with hair biology through multiple mechanisms: direct dermal papilla activation, stem cell mobilization, vascular support for the follicle's blood supply, and modulation of the inflammatory scalp environment. Different peptide compounds target different mechanisms, which is why evidence from one compound does not generalize to the category.

Peptides Studied for Hair Growth: A Quick Comparison

The following peptides have published evidence relevant to hair follicle biology. They are ordered by strength of clinical evidence, from most-studied in human-relevant models to least.

• Compound: GHK-Cu (glycine-histidine-lysine copper complex)
  Mechanism (preclinical): Copper-peptide complexes (AHK-Cu and GHK-Cu) have been reported in preclinical models to stimulate dermal papilla cell proliferation, elongate hair follicles ex vivo, support scalp ECM remodeling, and activate stem cell recovery
  Evidence: Ex vivo human follicle data is primarily from AHK-Cu (Pyo et al. 2007), a structurally related copper-tripeptide. GHK-Cu shares the copper-chelating mechanism but has different human-follicle-specific evidence. Additional animal studies (Trachy et al. 1991), combination clinical data (Kuceki et al. 2025, combination tattooing), and skin stem cell data (Choi et al. 2012) support the compound class.
  FDA status: Not FDA-approved for any indication. Topical GHK-Cu is regulated as a cosmetic ingredient. Injectable GHK-Cu was removed from FDA's interim Category 2 list in April 2026 without placement on Category 1 — not eligible for 503A compounding as of publication.
  SP availability: Not available through Superpower
  Route: Topical (OTC cosmetic ingredient); injectable form is not eligible for 503A compounding as of April 2026 and is not available in any licensed channel.
• Compound: Biomimetic peptide combinations
  Mechanism for hair growth: Varied peptide combinations that mimic growth factor signaling relevant to follicle activation
  Evidence: RCT by Rinaldi et al. 2019 (PRP-like biomimetic peptide cosmetic in alopecia areata); Loing et al. 2013 (combination peptide synergy for alopecia)
  FDA status: Cosmetic or compounded; not FDA-approved for hair loss
  SP availability: Not currently available through Superpower as a standard formulation
  Route: Topical
• Compound: Thymosin beta-4 (TB4) / TB-500
  Mechanism (preclinical): In animal models, reported to activate hair follicle stem cells, drive telogen-to-anagen transition, and support angiogenesis and vascular supply to the follicle
  Evidence: Multiple animal studies (Philp et al. 2004; Philp et al. 2007; Gao et al. 2015); no completed human hair growth clinical trial published
  FDA status: Not FDA-approved for any indication. Not on the FDA 503A bulks list; no USP-NF monograph; not a component of any FDA-approved drug. Not eligible for 503A compounding.
  SP availability: Not available through Superpower
  Route: Research context only
• Compound: AHK-Cu (alanyl-histidyl-lysine copper complex)
  Mechanism for hair growth: Direct ex vivo hair follicle elongation and dermal papilla cell proliferation
  Evidence: Ex vivo human follicle elongation data (Pyo et al. 2007); related to but distinct from GHK-Cu
  FDA status: Not FDA-approved; available in topical cosmetic formulations
  SP availability: Not currently available through Superpower as a standalone
  Route: Topical
• Compound: AP collagen peptides
  Mechanism (preclinical): Activates GSK-3β/β-catenin (Wnt) pathway in preclinical models; reported to support hair shaft production and follicle activation in mouse models
  Evidence: In vivo mouse data and in vitro pathway evidence (Lee et al. 2024)
  FDA status: Dietary supplement context; cosmetic ingredient context; not FDA-approved for hair loss
  SP availability: Not available through Superpower
  Route: Oral or topical

Thymosin beta-4 / TB-500 is listed as research-only. TB-500 has not been approved by the FDA for any medical use. Research is limited to animal studies. It is not available through Superpower or any licensed prescriber for hair growth or any other indication in the US. Its inclusion here is for educational context only.

Peptides Studied for Hair Growth: Individual Profiles

Each compound requires individual evaluation because mechanisms, evidence quality, and regulatory status differ substantially. An evidence statement about one compound does not apply to the category as a whole.

GHK-Cu: a widely studied peptide in follicle biology

GHK-Cu is an endogenous human tripeptide — glycine, histidine, lysine — that chelates copper and declines in plasma concentration with age. Its connection to hair biology begins with foundational animal work: Trachy and colleagues, in a 1991 Annals of the New York Academy of Sciences study, showed peptide copper complexes in C3H mice stimulate hair follicle growth — the first direct evidence linking copper-peptide complexes to hair follicle activation in an animal model. A companion review by Uno and Kurata in 1993 surveyed the broader evidence for peptides in hair biology.

The most direct evidence for human follicle activity comes from a 2007 study by Pyo and colleagues in Archives of Pharmacal Research, reporting that a tripeptide-copper complex in human follicles ex vivo elongated the follicles and stimulated dermal papilla cell proliferation in vitro — a study using actual human follicles in organ culture, not animal models. Note that the tested compound was a tripeptide-copper complex of the GHK-Cu family, not GHK-Cu itself; both share the copper-chelating mechanism, and the ex vivo human follicle data is specifically from the tested tripeptide-copper complex. [Ex vivo human follicle model — tripeptide-copper complex]

Pickart and Margolina's 2018 comprehensive review in the International Journal of Molecular Sciences described GHK-Cu regenerative actions including tissue remodeling and hair follicle regeneration, with reference to collagen, elastin, and angiogenic activity in the scalp environment. Choi and colleagues, in a 2012 Journal of Peptide Science paper, demonstrated copper-free GHK in skin stem cells — establishing that the tripeptide sequence itself, independent of copper chelation, has regenerative effects on follicle stem cell populations. Maquart and colleagues' 1988 study in FEBS Letters established GHK-Cu collagen synthesis in fibroblasts beginning at femtomolar concentrations, which is relevant because the scalp dermis requires intact ECM for follicle anchoring and dermal papilla function.

The most recent clinical-adjacent evidence: Kuceki and colleagues' 2025 study in JAAD International evaluated a combination tattooing procedure using minoxidil, dutasteride, and a copper peptide; the combination arm showed greater AI-assessed hair regrowth than established-treatment monotherapy arms. The study does not isolate the copper peptide's independent contribution. A companion 2025 paper by Gold and colleagues in the Journal of Cosmetic and Laser Therapy evaluated biomimetic peptide as FUE graft media, reporting that peptides have been studied as donor scalp media in FUE procedures, supporting follicle viability in the graft-storage context. [Clinical observation — FUE surgical graft-storage context, not a hair-growth outcome] [Clinical combination study — peptide's independent effect not isolable]

GHK-Cu is not FDA-approved for any indication including hair growth. Its use for hair growth has not been approved by the FDA. The safety and efficacy for this use have not been established through adequate and well-controlled clinical trials. In April 2026, FDA removed injectable GHK-Cu from its interim Category 2 list without placing it on Category 1. Injectable GHK-Cu is not on the FDA 503A bulks list and is not eligible for 503A compounding in the United States as of publication. It is not available through Superpower. Topical GHK-Cu in cosmetic formulations remains regulated under FDA cosmetics law and is available over the counter; cosmetic ingredients are not evaluated or approved by the FDA to diagnose, treat, cure, or prevent any disease.

Jiang and colleagues documented GHK-Cu and hyaluronic acid synergy on collagen IV upregulation in a 2023 paper — supporting the rationale for GHK-Cu in combination scalp treatments rather than as a standalone agent. Mortazavi and colleagues' 2024 review in BioImpacts of topically applied GHK specifically addressed formulation problems and prospective developments for topical delivery — penetration to hair follicles remains the key constraint for topical applications.

Thymosin beta-4 (TB4) and TB-500: the stem cell mobilization compound

Thymosin beta-4 is a 43-amino-acid peptide naturally expressed in most body tissues that plays fundamental roles in actin dynamics, cell migration, and tissue repair. Its connection to hair biology was established by Philp and colleagues in a foundational 2004 FASEB Journal paper demonstrating hair follicle stem cell activation in mice — establishing the stem cell mobilization mechanism as the primary pathway through which TB4 promotes anagen initiation in preclinical models. Philp and colleagues confirmed and extended this in a 2007 Annals of the New York Academy of Sciences paper showing TB4 stem cell migration in mice, specifically describing how TB4 drives follicle stem cells toward the base of the follicle during anagen onset. [Animal study]

Dai and colleagues published a comprehensive 2021 review in the Journal of Cellular and Molecular Medicine covering thymosin β4 in hair follicle development, including angiogenesis, ECM remodeling, and stem cell regulation across the full hair cycle. Gao and colleagues, in a 2015 PLoS One paper, showed thymosin beta-4 in mice induces hair growth, demonstrating in vivo evidence supporting the telogen-to-anagen transition. Philp and colleagues, in a 2004 Mechanisms of Ageing and Development paper, documented TB4 angiogenesis and wound healing — relevant because hair follicle growth requires adequate vascular supply. [Animal study — all available evidence]

TB-500 is a synthetic peptide corresponding to amino acids 17-23 of thymosin beta-4 (the actin-binding domain), marketed based on proposed similar mechanisms. Neither thymosin beta-4 nor TB-500 is FDA-approved for any indication. TB-500 is not on the FDA 503A bulks list, has no USP-NF monograph, and is not a component of any FDA-approved drug. Under Section 503A, TB-500 is therefore not eligible for compounding in the United States. Research is limited to laboratory and animal studies. No completed human clinical trial for TB-500 or thymosin beta-4 as a hair growth treatment has been published. TB-500 is not prescribed, compounded, or dispensed through Superpower. Inclusion here is for educational context only.

Biomimetic peptide combinations: RCT-level topical evidence

Published RCT-level evidence for peptides in hair loss is most developed for specific cosmetic formulations rather than single-compound approaches. Rinaldi and colleagues published a randomized controlled study in the Journal of Dermatological Treatment in 2019 evaluating a biomimetic peptide in alopecia areata, reporting measurable hair regrowth outcomes in the tested formulation. This is a single-product result and does not generalize to "biomimetic peptide formulations" as a class. [Controlled clinical study — single product] Loing and colleagues published a 2013 clinical study in the Journal of Cosmetic Science reporting that a peptide combination and hair shedding were evaluated, with the tested combination associated with reduced hair shedding versus individual components in the studied population. [Clinical study]

Microneedle delivery may enhance follicular peptide delivery: Li and colleagues, in a 2015 Pharmaceutical Research paper, demonstrated microneedle delivery of GHK into follicles — establishing feasibility of targeted follicular penetration and supporting discussion of topical vs. injectable routes. Jiang and colleagues' 2023 paper on GHK-Cu and hyaluronic acid synergy supports combination product formulation.

AP collagen peptides and Wnt pathway activation

Collagen-derived peptides beyond GHK-Cu are also being studied for follicle activation. Lee and colleagues published a 2024 Experimental Dermatology study reporting that AP collagen peptides and GSK-3β/β-catenin pathway activation promote hair growth in mouse models and improve hair condition in both in vitro and in vivo mouse models — connecting dietary-source peptides to the Wnt signaling cascade that governs anagen initiation in preclinical models. [Animal study / in vitro] This preclinical evidence does not establish AP collagen peptides as a hair growth treatment in humans but supports the mechanistic rationale for research on peptide-based approaches to Wnt pathway modulation in follicle biology.

Regulatory Status at a Glance

As of April 2026, the following regulatory positions apply to compounds discussed in this article.

• GHK-Cu (topical, cosmetic): Cosmetic ingredient regulated under FDA cosmetics law (21 U.S.C. § 361); not FDA-approved for any indication; OTC, no prescription required
• GHK-Cu (injectable): Not FDA-approved for any indication. In April 2026, FDA removed injectable GHK-Cu from its Category 2 interim bulks list without placing it on Category 1. Injectable GHK-Cu is not eligible for 503A compounding and has no legal prescribing or dispensing pathway in the United States as of publication. Injectable GHK-Cu is not available through Superpower.
• AHK-Cu (topical): Cosmetic ingredient; not FDA-approved; OTC
• Thymosin beta-4 / TB-500: Not FDA-approved for any indication. Not on the FDA 503A bulks list; no USP-NF monograph; not a component of any FDA-approved drug. Not eligible for 503A compounding. Not available through Superpower.
• Biomimetic peptide combinations (topical): Cosmetic ingredient category; not FDA-approved as drug products
• Minoxidil, finasteride, dutasteride (non-peptides): FDA-approved treatments for androgenetic alopecia. Minoxidil is a pyrimidine derivative (small molecule, originally developed as an antihypertensive); finasteride and dutasteride are 5-alpha-reductase inhibitors. None is a peptide. Referenced in this article for evidence-base comparison only.

Important: As of April 2026, there is no FDA-approved peptide drug for hair loss or hair growth. The FDA-approved treatments for androgenetic alopecia — topical and oral minoxidil, finasteride, and dutasteride — are not peptides. These compounds are included here for evidence-base comparison only; they are not interchangeable with the peptide compounds discussed in this article.

The intended-use doctrine (21 CFR 201.128) means that a cosmetic peptide product making claims to "treat hair loss," "regrow hair," or "reverse follicle miniaturization" becomes a drug requiring FDA approval — regardless of labeling. Cosmetic peptide products stay within cosmetic law only when claims remain limited to appearance and feel.

Considerations When Comparing Peptides for Hair Growth

Comparing peptides for hair growth requires explicit acknowledgment of the methodological limitations. The compounds in this category have been studied in different species (mice, rabbits, humans), using different models (in vitro cell cultures, ex vivo follicle preparations, in vivo animal models, clinical trials), at different doses, and with different endpoints. Inferring relative effectiveness across these separate evidence bases is not reliable.

Your specific hair loss type: Androgenetic alopecia (pattern baldness), alopecia areata (autoimmune), telogen effluvium (diffuse shedding), and traction alopecia have different underlying mechanisms. A peptide that addresses one mechanism may be irrelevant for another. A provider evaluation that diagnoses the specific pattern is the prerequisite for any evidence-based treatment conversation.

Modifiable contributors first: Before peptide protocols, correctable deficiencies — iron (ferritin), B12, thyroid function — are the higher-priority targets. Hair loss driven by iron deficiency will not respond meaningfully to follicle-stimulating peptides until the deficiency is corrected.

Evidence level: FDA-approved non-peptide treatments (minoxidil, finasteride, dutasteride for androgenetic alopecia) have large-scale human trial evidence. Peptide approaches have early-stage evidence at best. A provider will factor this hierarchy into recommendations, typically establishing response to proven treatments before evaluating peptides under study.

Combining approaches: Kuceki and colleagues' 2025 combination tattooing study evaluated minoxidil, dutasteride, and a copper peptide delivered together; the study design does not isolate the copper peptide's independent contribution. Combination protocols of this kind are research findings, not approved treatment regimens.

Route and access: Topical OTC cosmetic peptide formulations are accessible without clinical involvement. Injectable GHK-Cu is not eligible for 503A compounding as of publication and has no legal prescribing pathway. TB-500 and TB4 have no legal prescribing pathway.

This is not an exhaustive list. A dermatologist or trichologist will evaluate your specific pattern, scalp biology, and baseline labs before recommending any intervention.

Safety Considerations

Safety profiles vary significantly across this compound class, from cosmetic ingredients with established safety records to experimental compounds with no human safety data.

Topical cosmetic peptide formulations — GHK-Cu in cosmetic concentrations, AHK-Cu, biomimetic combinations — have the safety context of cosmetic ingredients: addressed through the CIR (Cosmetic Ingredient Review) process and decades of consumer use, with contact sensitization as the most commonly reported risk. Systemic effects from topical cosmetic doses have not been prominently reported in the available evidence.

Injectable GHK-Cu has no legal compounding pathway in the US as of publication (see Regulatory at a Glance). Historical compounded injectable GHK-Cu carried injection-site risks (bruising, swelling, infection potential) and lacks long-term human safety data for the hair growth application specifically. Compounded products are not FDA-reviewed for safety, efficacy, or manufacturing quality under an NDA.

TB-500 / thymosin beta-4 has no published human safety data for injectable administration. Mendias and Awan, in a 2026 Sports Medicine review, characterized unapproved peptides as showing "rigorous human safety data scarce, and potential for serious harm." The absence of a legal compounding pathway reflects both the safety-data gap and the statutory bulks-list criteria, not merely a regulatory formality.

Contraindications that apply broadly to hair growth peptide therapy include:

• Active scalp infection or dermatitis — injectable procedures and some actives are contraindicated in inflamed or infected scalp tissue
• Pregnancy or breastfeeding — no reproductive safety data for injectable GHK-Cu; standard caution for any injectable compound
• Known hypersensitivity to the compound or formulation components
• Hormone-sensitive conditions — androgens drive follicle miniaturization in androgenetic alopecia; some peptides interact with growth factor pathways that may be relevant in hormone-sensitive contexts; provider evaluation required
• Copper metabolism disorders (Wilson's disease) — GHK-Cu delivers exogenous copper

For compound-specific side effect profiles, consult the individual compound pages linked above or DailyMed for FDA-approved treatments.

What to Test Before Starting Peptides for Hair Growth

Regardless of which compound is under consideration, baseline biomarker testing establishes whether modifiable systemic factors are driving hair loss before any peptide protocol is initiated. Without this baseline, there is no objective way to separate a peptide response from spontaneous change, nutritional correction, or natural hair cycle variation.

• Ferritin: The most sensitive biomarker for iron-deficiency hair loss, frequently low before hemoglobin falls outside the reference range. Iron deficiency is among the most common reversible causes of diffuse hair thinning. Testing ferritin before any hair growth protocol is essential — hair loss driven by iron deficiency will not respond meaningfully to follicle-stimulating peptides until the deficiency is corrected.
• Vitamin B12: B12 deficiency is associated with diffuse hair thinning and accelerated cell turnover impairment. Common in adults over 50, vegetarians, and those on proton pump inhibitors. Testing vitamin B12 rules out this correctable contributor before peptide therapy begins.
• TSH (thyroid-stimulating hormone): Both hypothyroidism and hyperthyroidism cause hair thinning and altered hair texture. Thyroid dysfunction is one of the most common systemic causes of hair loss and is directly treatable. Testing TSH rules out this diagnosis before any hair growth intervention; the TSH guide explains what the value means in context.
• hs-CRP: Systemic and scalp inflammation contributes to follicle miniaturization in androgenetic alopecia and is a driver of alopecia areata. Testing hs-CRP establishes the inflammatory context that affects follicle biology independently of peptide effects.
• IGF-1: Growth hormone axis marker relevant to dermal papilla function and scalp ECM. GHK-Cu's regenerative mechanisms overlap with growth-factor signaling pathways. IGF-1 testing establishes the GH-axis baseline before any injectable compound that modulates these pathways is initiated.
• SHBG and total testosterone: For androgenetic alopecia specifically, the androgen balance — DHT availability driven by free testosterone and SHBG — determines follicle miniaturization rate. Understanding this context informs whether anti-androgen strategies should accompany any peptide approach.
• Zinc: Zinc deficiency is associated with hair loss and is detectable through serum zinc testing. A confirmable zinc deficiency is treated with supplementation — not with peptides.

Ferritin, vitamin B12, TSH, and hs-CRP together identify the most common reversible causes of hair loss. IGF-1 provides the GH-axis context for injectable peptide consideration. A hair loss panel that includes these markers establishes the objective baseline from which any treatment decision should begin.

How to Access These Peptides Safely

Access pathways differ by compound and formulation type.

Topical cosmetic GHK-Cu and related copper peptide formulations are available OTC without prescription. Quality and concentration vary significantly across products. No regulatory body evaluates cosmetic efficacy claims.

Injectable GHK-Cu is not on the FDA 503A bulks list and is not eligible for 503A compounding in the United States as of publication, following FDA's April 2026 removal of GHK-Cu from the Category 2 interim list without Category 1 placement. Injectable GHK-Cu is not available through Superpower.

TB-500 and thymosin beta-4 injectable compounds are not available through legal prescribing channels in the US. Products sold as TB-500 online are not subject to FDA manufacturing standards. They are not prescribed, compounded, or dispensed through Superpower.

The Kuceki and colleagues 2025 combination study evaluated a clinician-administered tattooing research procedure combining established drugs with a copper peptide — a research protocol, not an approved treatment regimen. The study cannot isolate the peptide's independent contribution.

Understanding Your Baseline

Hair loss has multiple potential drivers: androgenic, nutritional, inflammatory, thyroid-related, or stress-induced. Peptides address specific molecular mechanisms — follicle stem cell activation, dermal papilla stimulation, ECM remodeling — but cannot address a ferritin deficiency, a thyroid condition, or a DHT-driven follicle miniaturization cascade that hasn't been identified. Testing first establishes which of these factors is operative in your specific biology, transforming the question from "which peptide should I try" to "what does my biology show about what's driving this."

That is the central principle of Superpower's approach to preventive health. With hair loss as with any complex biological process, objective data precedes intervention — not because peptides are ineffective, but because knowing what you're treating makes every subsequent decision more precise.

IMPORTANT SAFETY INFORMATION

GHK-Cu (glycine-histidine-lysine copper complex) is not FDA-approved for any indication, including hair growth. GHK-Cu's use for hair growth has not been approved by the FDA; the safety and efficacy for this use have not been established through adequate and well-controlled clinical trials. In April 2026, FDA removed injectable GHK-Cu from its interim Category 2 bulks list without placing it on Category 1. Injectable GHK-Cu is not on the FDA 503A bulks list, has no USP-NF monograph, is not a component of an FDA-approved drug, and is therefore not eligible for 503A compounding in the United States as of publication. Injectable GHK-Cu is also not on the 503B clinical need list; no 503B outsourcing facility compounding pathway is available. Injectable GHK-Cu is not available through Superpower. Topical GHK-Cu in cosmetic formulations is regulated as a cosmetic ingredient under FDA cosmetics law; cosmetic ingredients are not evaluated or approved by the FDA to diagnose, treat, cure, or prevent any disease.

AHK-Cu (alanyl-histidyl-lysine copper complex) is not FDA-approved for any indication. In topical cosmetic formulations, it is regulated as a cosmetic ingredient and is not evaluated or approved by the FDA to treat hair loss or any medical condition.

Thymosin beta-4 and TB-500 are not approved by the FDA for any medical use. TB-500 is not on the FDA 503A bulks list, has no USP-NF monograph, and is not a component of any FDA-approved drug; under Section 503A, it is not eligible for compounding in the United States. TB-500 is also not on the 503B clinical need list; no 503B outsourcing facility compounding pathway is available. Research on these compounds has been limited primarily to laboratory and animal studies, with no completed human clinical trial data for hair growth available. Safety, efficacy, appropriate dosing, and long-term effects in humans have not been established. Thymosin beta-4 and TB-500 are not prescribed, compounded, or dispensed through Superpower. Products sold as TB-500 through online channels are not manufactured to pharmaceutical-grade standards and carry contamination, dosing, and safety risks that cannot be mitigated by the end user. Their inclusion in this article is for educational context only.

Warnings: Unregulated online peptide products carry contamination and dosing risks and are outside the regulated pharmacy system. Historical injectable copper-peptide products delivered exogenous copper; individuals with copper metabolism disorders (Wilson's disease) should not use copper-peptide products. Reproductive safety data for copper-peptide injectables is not established.

FDA-approved treatments for androgenetic alopecia — topical minoxidil, oral minoxidil, finasteride, and dutasteride — are not peptides. Minoxidil is a pyrimidine derivative; finasteride and dutasteride are 5-alpha-reductase inhibitors (small molecules). These non-peptide drugs have substantially larger human trial evidence bases than any peptide discussed in this article and are referenced for evidence-base comparison only. Full prescribing information for FDA-approved hair loss treatments is available at dailymed.nlm.nih.gov.