Hair and Scalp Protocol Components in 2026: What the Literature Supports for Each Formulation Class

A hair and scalp protocol in 2026 is assembled from formulation classes that were developed decades apart, for different reasons, and with very different amounts of evidence behind them. Oral finasteride carries an FDA-approved label with three decades of use. Topical minoxidil is an over-the-counter product whose mechanism was only worked out properly in the last ten years. Copper tripeptides and extracellular vesicles sit at the other end of that spectrum, with follicle culture and early human data and no approval for any hair indication. A practice that sources across that range is well served by knowing which shelf each component sits on.

This article maps the components a licensed practice can source for hair and scalp work, what the peer-reviewed literature and the regulators say about each, and where the deeper reading lives. It is written for practitioners and practice operators, it makes no claim that any product does anything, and every finding below is attributed to the study or the agency that reported it. Deep-dive articles on each component follow in this series, and the evidence pages under the Science section of this site carry the same references with study designs labelled.

The follicle runs on a shift schedule, and every component acts on one of four levers

A hair follicle is a small organ that cycles through a growth phase (anagen), a brief regression phase (catagen) and a resting phase (telogen) before shedding and starting again. The dermal papilla, a cluster of specialised mesenchymal cells at the base of the follicle, is the signalling hub that decides when each phase begins and how long it lasts, and the Wnt and beta-catenin pathway is the most studied of the signals it uses to call anagen, as the Cold Spring Harbor review of Wnt signalling in skin describes.

A factory that runs three shifts is a fair analogy for the cycle, with the qualification that the analogy describes timing and not mechanism. Anagen is the long production shift, catagen is the short changeover, and telogen is the idle period before the next crew clocks in. In androgenetic alopecia the production shift is progressively shortened and the follicle miniaturises over successive cycles, which is why the literature on pattern hair loss is largely a literature about lengthening anagen and interrupting the signal that shortens it.

Every formulation class in a hair protocol acts on one of four levers in that schedule: the androgen signal that shortens anagen, the follicular blood flow and enzyme activity that minoxidil depends on, the paracrine signalling into the dermal papilla, and the scalp environment in which the follicle sits. The sections below take the components in that order, and the table near the end sorts them by what a practice can actually source.

The androgen lever: finasteride has the label, and the topical form has an FDA alert

Finasteride inhibits type II 5-alpha-reductase, the enzyme that converts testosterone to dihydrotestosterone in the scalp, and the approved one-milligram oral product carries an FDA label indicated for male pattern hair loss in men only. The label states that daily use for three months or more is generally necessary before benefit is observed, and the 2017 systematic review and meta-analysis by Adil and Godwin in the Journal of the American Academy of Dermatology reported that oral finasteride and topical minoxidil each outperformed placebo on hair count across the randomised trials it pooled.

Topical finasteride is a different product with a different regulatory status. A 2022 phase III randomised trial by Piraccini and colleagues in the Journal of the European Academy of Dermatology and Venereology studied a 0.25% finasteride spray and reported target-area hair count gains over vehicle with lower systemic exposure than the oral tablet, and a 2025 meta-analysis of seven randomised trials in Frontiers in Medicine reported that a mixed minoxidil and finasteride solution outperformed minoxidil alone on hair density, hair diameter and global assessment. Neither finding creates an approved product. In April 2025 the FDA alerted providers, compounders and consumers that it had received 32 adverse event reports for compounded topical finasteride between 2019 and 2024, that the events were consistent with the oral label, that most persisted after discontinuation, and that no FDA-approved topical formulation of finasteride exists.

The oral label itself is a prescriber matter rather than a supplier matter, and this series handles it that way. Pharmacovigilance analyses of the FDA Adverse Event Reporting System published in 2025 in PLoS One and in Pharmaceuticals examined sexual, psychiatric and suicidality signals associated with finasteride, and the European Medicines Agency in May 2025 added suicidal ideation to the product information with a patient card. The oral tablet is an approved product dispensed against an ordinary prescription, and the counselling conversation belongs to the prescriber.

Two smaller molecules act on the same lever and appear in compounded scalp solutions as adjuncts. Ketoconazole, an antifungal, was studied as a 2% shampoo in a 1998 Dermatology paper by Piérard-Franchimont and colleagues that reported changes in hair density and anagen proportion over long-term use, and a 2004 hypothesis paper in Medical Hypotheses proposed it as an adjunct to finasteride. Azelaic acid was reported to inhibit 5-alpha-reductase activity in human skin in a 1988 British Journal of Dermatology study by Stamatiadis and colleagues, an in vitro finding that has been carried into combination solutions ever since without a trial of the four-ingredient combination itself.

The blood-flow lever: minoxidil is a prodrug, and the enzyme that activates it can be induced

Minoxidil arrives at the follicle inactive. Sulfotransferase enzymes in the outer root sheath convert it to minoxidil sulfate, the form that acts, and a 2020 Dermatologic Therapy study by Ramos and colleagues reported that sulfotransferase activity measured in plucked follicles predicted which patients responded to topical minoxidil. That observation reframed a long-standing puzzle, because the non-response rate to topical minoxidil had been attributed to adherence and to disease severity when a good part of it was enzymatic.

Tretinoin enters the story as an enzyme inducer rather than as a hair molecule in its own right. A 2019 Dermatologic Therapy study by Sharma, Goren and colleagues reported that five days of topical tretinoin raised follicular sulfotransferase expression and converted 43% of subjects predicted to be minoxidil non-responders into responders, which is the mechanistic basis for the minoxidil and tretinoin solutions in compounded formularies. The pairing is older than the mechanism: Bazzano and colleagues reported on topical tretinoin with minoxidil in the Journal of the American Academy of Dermatology in 1986.

Topical minoxidil at 2% and 5% is FDA-approved as an over-the-counter product. A compounded 5% solution that adds tretinoin, or that adds finasteride, azelaic acid and ketoconazole, is a different product under 503A, prepared to an individual prescription and dated with a beyond-use date rather than a shelf life. The compounded hair and scalp formulations page on this site lists what the pharmacy can prepare and how each preparation is dated, and it deliberately says nothing about what any of them does to hair.

The signalling lever: copper tripeptides, thymosin beta-4 and extracellular vesicles carry the least human data and the most interest

GHK-Cu is a naturally occurring tripeptide, glycyl-histidyl-lysine, complexed with copper. The 2018 review by Pickart and Margolina in the International Journal of Molecular Sciences summarised gene-expression, angiogenic and matrix-remodelling actions reported across the wound and skin literature. The hair-specific evidence is narrower than the reputation: a 2007 Archives of Pharmacal Research study by Pyo and colleagues reported that a tripeptide-copper complex elongated human hair follicles in organ culture and increased dermal papilla cell proliferation, and the peptide in that study was AHK-Cu, a structural relative of GHK-Cu rather than GHK-Cu itself. Uno and Kurata reported follicle effects of copper-binding peptides in a macaque model in a 1993 Journal of Investigative Dermatology supplement. No randomised trial of GHK-Cu in human pattern hair loss has been published.

Thymosin beta-4 is a 43-residue protein, and TB-500 is a seven-residue fragment of it that is routinely marketed on the protein’s research. Philp and colleagues reported in the FASEB Journal in 2004 that thymosin beta-4 increased hair growth in rats and mice by activating follicle stem cells, and a 2015 PLoS One study reported similar effects in a mouse model. The data are animal data, and the evidence page for TB-500 on this site states the distinction between the fragment and the protein plainly.

Extracellular vesicles, usually called exosomes in the aesthetic market, are the most actively studied signalling class and the one with the clearest regulatory boundary. Two 2025 systematic reviews, one in Clinical, Cosmetic and Investigational Dermatology by Al Ameer and colleagues and one in Cureus by Darwish and colleagues, catalogued the clinical evidence across alopecia types and compared it with PRP and minoxidil, and both characterised the human literature as early, heterogeneous in vesicle source, and short on randomised trials. The randomised data that exist are small: a 2025 pilot trial in Life by Amini and colleagues studied a plant-derived exosome formulation in men, and a 2025 Journal of Drugs in Dermatology study by Ablon and colleagues paired an exosome complex with microneedling in subjects with self-perceived thinning hair. Registered trials are now recruiting, including a randomised umbilical-cord vesicle trial whose protocol was published in the FASEB Journal in 2026 and a 2024 Stem Cell Research and Therapy study of vesicles from hyaluronic-acid-stimulated induced mesenchymal stem cells.

The regulatory position is older than most of that literature and has not moved. The FDA’s public safety notification on exosome products, issued in December 2019, states that there are no FDA-approved exosome products and that exosomes used to treat diseases and conditions in humans are regulated as drugs and biological products subject to premarket review. ExaVeyra supplies exosome material for research use only, with a lot-specific certificate of analysis, and the material is described on this site by its available formats and never by a dose. The existing article on exosomes and hair restoration research on this blog is being expanded to the depth of this series and carries the follicle biology in detail.

The environment lever: nutrition, hormones and the lab notice that catches practices out

Nutritional and endocrine context appears throughout the alopecia literature as association rather than as intervention. A 2024 systematic review and meta-analysis in Frontiers in Nutrition by Yongpisarn and colleagues reported vitamin D deficiency in roughly 38% to 54% of patients across alopecia areata, female and male pattern hair loss, telogen effluvium and scarring alopecias, and a 2023 Cureus review by Hussein and colleagues described diffuse shedding in both hypothyroidism and hyperthyroidism. Both are reasons a prescriber orders labs; neither is a claim about a supplement.

Biotin deserves its own paragraph because it is the component most often assumed and least often supported. The 2024 review by Yelich and colleagues in the Journal of Clinical and Aesthetic Dermatology concluded that the evidence supports biotin only in documented deficiency states and specific inherited or medication-related conditions, and found no support for routine supplementation in people without deficiency. The FDA’s safety communication, updated in November 2019, warns separately that biotin in a patient’s sample can interfere with laboratory assays and cause falsely low troponin results, which makes biotin a laboratory disclosure item as much as a formulary item.

Hormone optimisation practices carry a further consideration. Androgenic agents, including testosterone, can unmask or accelerate pattern hair loss in predisposed people, and a 2021 JAMA Dermatology cohort by Thoreson and colleagues reported the incidence of androgenetic alopecia in patients receiving masculinising hormone therapy. On the estrogen side, a 2012 phase IV study in Annals of Dermatology by Kim and colleagues studied topical 17-alpha-estradiol in female pattern hair loss, and there is no FDA-approved topical estrogen for hair. ExaVeyra does not supply controlled substances, and the hormonal context appears in this series so that a practice running both programmes can read the same literature its prescribers read.

Procedure adjuncts: microneedling has meta-analyses, and scalp comfort has approved anaesthetics

Scalp microneedling is the procedural component with the best-organised evidence. A 2024 systematic review and meta-analysis of randomised trials in the Journal of Cosmetic Dermatology by Pei and colleagues reported greater hair density and diameter when microneedling was combined with a topical agent than with the topical alone, and a 2025 Clinical Dermatology scoping review with a prospective series by Koumprentziotis and colleagues described radiofrequency microneedling followed by topical exosome application. The device line and the cosmetic line are distinct, and the clinic-launch guide on topical application and microneedling on this site explains why a cleared microneedling device is cleared to needle rather than to deliver.

Topical anaesthetics are the quiet adjunct. A 2013 Journal of Drugs in Dermatology study by Cohen and Gold reported pain management with a lidocaine and tetracaine cream across laser procedures, and compounded lidocaine and tetracaine creams, with or without benzocaine or phenylephrine, appear in formularies for scalp procedures for the same reason. PRP sits beside all of this as an autologous option with systematic-review support of its own, and the CuraCator clinical method article on this blog covers its preparation and delivery.

What a licensed practice can source today, sorted by regime

Two regimes appear in a hair protocol and they never share vocabulary. Exosome material is research-use material, supplied to verified practices with a certificate of analysis and described by format. Compounded scalp formulations are prescription products prepared under section 503A by our 503A pharmacy partner, licensed by the Texas State Board of Pharmacy, for an individual patient, and they are available only in the states where that pharmacy holds a non-resident license. The state hair guides on this site say which states those are.

The table sorts by regime and by evidence and nothing else. It is not a ranking of what works, because the literature does not support one across classes with such different designs, and a practice choosing between rows is making a prescribing decision that this site does not take part in.

• Deep dives in this series: finasteride and 5-alpha-reductase; minoxidil and sulfotransferase; ketoconazole and azelaic acid; GHK-Cu and the follicle; thymosin beta-4 and TB-500; nutritional cofactors; the hormonal context; scalp microneedling and anaesthesia; and the expanded exosome article.
• Evidence pages: the Hair and Scalp Science hub under the Science section carries the same references with each study design labelled beside the citation.
• Sourcing pages: the compounded hair and scalp formulations page lists what the pharmacy can prepare and how it is dated; the exosome product pages list available formats.

Closing Observation

The components of a hair protocol do not share an evidence base, and the honest map of them has three regions. Oral finasteride and topical minoxidil sit in approved territory with meta-analyses behind them. Compounded combinations of those actives with tretinoin, ketoconazole and azelaic acid sit in a region where the individual ingredients have studies and the combinations mostly do not, and where an FDA alert on compounded topical finasteride now governs the conversation. Copper tripeptides, thymosin beta-4 and extracellular vesicles sit in a region of follicle culture, animal models and small early trials, with no approval for any hair indication and, for exosomes, a safety notification that states so.

What the literature does not support is the flattening of those three regions into one menu, which is what much of the market does next. A practice that holds the map will source each component from the right regime, will describe it to patients in the terms its own evidence allows, and will be considerably harder to sell a solution to on the strength of the most confident sentence in a brochure.