---
canonical_name: Sh-Polypeptide-86
alternate_names: Synthetic Human Follistatin, Recombinant Follistatin Peptide, Follistatin, sh-Polypeptide-86
canonical_topic: Sh-Polypeptide-86 for Hair Regrowth
short_topic_lc: sh_polypeptide_86_hair
creation_date: 2026-0630-0038
creator_ai_fullname: Opus 4.8
---
# Sh-Polypeptide-86 for Hair Regrowth
Evidence Review created on 06/30/2026 using [AI4L](https://github.com/forever-healthy/AI4L) / Opus 4.8
**Also known as:** Synthetic Human Follistatin, Recombinant Follistatin Peptide, Follistatin, sh-Polypeptide-86
## Motivation
Sh-Polypeptide-86 is a lab-made protein designed to copy human follistatin, a natural substance the body uses to switch off other proteins that tell cells to stop growing. In hair products it is sold under the name "follistatin" and added to serums applied to the scalp, where the goal is to wake up resting hair follicles and lengthen the active growing phase of the hair. It is best known as one of eight peptides in a widely publicized scalp serum.
Follistatin reached the hair-loss conversation through a different door: it first drew attention for blocking myostatin, a protein that limits muscle size. Researchers later noticed that the same family of "stop-growing" signals also shrinks hair follicles, which raised the question of whether blocking them could help hair. A single early human study that combined follistatin with other growth signals reported thicker, denser hair, fueling interest.
This review examines what is actually known about Sh-Polypeptide-86 applied to the scalp for hair regrowth: how it is thought to work, the strength and limits of the evidence behind it, its safety and sourcing, and the practical questions of whether a large protein in a topical serum can reach the follicle at all.
**[Benefits](#expected-benefits) - [Risks](#potential-risks--side-effects) - [Protocol](#therapeutic-protocol) - [Conclusion](#conclusion)**
## Recommended Reading
This section lists high-level, directly relevant expert and clinical resources that give a useful overview of Sh-Polypeptide-86 and follistatin for hair.
* [Blueprint Haircare Stack: Product Review](https://perfecthairhealth.com/blueprint-haircare-stack-product-review/) - Rob English
A detailed independent analysis of the scalp serum in which Sh-Polypeptide-86 is the headline "follistatin" peptide, concluding that no preclinical or clinical efficacy data exist for the ingredient and that topical delivery of such a large protein is the central unresolved problem.
* [Blueprint Hair Peptides Analysis](https://klaustownsend.com/blueprint-hair-peptides-analysis/) - Klaus Townsend
An ingredient-by-ingredient breakdown of each synthetic peptide in the serum, including Sh-Polypeptide-86, that maps each one to the human protein it imitates and weighs the plausibility of a topical effect.
* [AMA #63: A guide for hair loss: causes, treatments, transplants, and sex-specific considerations](https://peterattiamd.com/ama63/) - Peter Attia
A structured overview of hair-loss biology and the evidence tiers behind mainstream and emerging treatments, useful for placing growth-factor and peptide approaches like follistatin in context against established options.
* [Hair regrowth following a Wnt- and follistatin containing treatment: safety and efficacy in a first-in-man phase 1 clinical trial](https://pubmed.ncbi.nlm.nih.gov/22052313/) - Zimber et al., 2011
The single most-cited human study linking follistatin to hair, reporting increased follicle density and hair-shaft thickness in 26 men after a single injection of a follistatin-and-Wnt growth-factor mixture; it is the origin of the follistatin-for-hair claim but tests injection, not a topical serum.
_Note: Only four resources of sufficient quality and direct relevance could be found, so fewer than five are listed; the list is not padded with marginal content. Of the priority experts, only Peter Attia had directly relevant published content on the topic — no relevant content on Sh-Polypeptide-86 or follistatin for hair was found from Rhonda Patrick, Andrew Huberman, Chris Kresser, or Life Extension._
## Grokipedia
No Grokipedia article exists for Sh-Polypeptide-86.
## Examine
No Examine article exists for Sh-Polypeptide-86. Examine.com focuses on ingestible dietary supplements and does not typically cover topical cosmetic peptide ingredients.
## ConsumerLab
No ConsumerLab article exists for Sh-Polypeptide-86. ConsumerLab tests ingestible supplements and does not typically cover topical cosmetic peptide ingredients.
## Systematic Reviews
No systematic reviews or meta-analyses for Sh-Polypeptide-86 were found on PubMed as of 06/30/2026.
## Mechanism of Action
The primary biological rationale for Sh-Polypeptide-86 rests on what it imitates: follistatin, a naturally occurring glycoprotein that binds and neutralizes members of the TGF-β superfamily (transforming growth factor beta, a large family of signaling proteins that broadly restrain cell growth). Its two most relevant targets in this context are activin and myostatin.
The hair-cycle logic runs as follows:
* **Activin/BMP braking.** In the hair follicle, activin signals interact with bone morphogenetic proteins (BMPs — growth-restraining signals of the same TGF-β family) to govern the timing of the hair cycle. Mouse work showed that follistatin promotes follicle development while activin retards it, and that follistatin-deficient mice have abnormal follicle formation, placing follistatin on the pro-growth side of this balance.
* **Myostatin in the follicle.** Myostatin (the muscle-limiting protein follistatin is most famous for blocking) is also expressed in skin and follicles, where it is associated with follicle miniaturization. By sequestering myostatin and activin, follistatin is proposed to lift these "stop-growing" signals from the follicle.
* **Anagen extension.** Removing these brakes is hypothesized to favor the transition into and maintenance of anagen (the active growing phase), increasing follicle density and hair-shaft caliber — the outcomes reported in the early human injection study.
Two competing considerations weigh against a meaningful effect from a topical serum. First, the dominant mechanistic evidence is in mice or in injected human studies, not topical application. Second, and more fundamentally, follistatin is a large protein (the human form spans up to 344 amino acids); the intact stratum corneum is a formidable barrier to molecules of this size, so whether enough biologically active peptide reaches the dermal papilla through topical application is unresolved and is the central mechanistic objection raised by independent reviewers.
Because Sh-Polypeptide-86 is a recombinant protein rather than a small-molecule drug, classic small-molecule pharmacology (half-life, hepatic metabolism via cytochrome enzymes, tissue distribution) is not the appropriate frame. Protein turnover is governed by local proteases in skin; circulating endogenous follistatin has a very short half-life (on the order of minutes to an hour), and topically applied protein is expected to be degraded locally rather than distributed systemically.
## Historical Context & Evolution
Follistatin was first characterized in the 1980s as an activin-binding protein in ovarian fluid, named for its ability to suppress follicle-stimulating hormone. Its profile changed dramatically when it was found to be a potent natural inhibitor of myostatin, making it a target of intense interest in muscle biology, muscular dystrophy gene therapy, and — informally — the performance-enhancement community.
The leap to hair came indirectly. Mouse studies in the early 2000s established follistatin and activin as regulators of follicle development and cycling. The pivotal translational moment was a 2011 first-in-man phase 1 study (Zimber et al.) in which a wound-healing-derived mixture containing follistatin and Wnt proteins, injected into the scalp, increased follicle density and hair-shaft thickness in men with pattern hair loss. This finding is the historical seed of every subsequent "follistatin for hair" claim.
The current product incarnation — Sh-Polypeptide-86 as a topical cosmetic ingredient — is a much more recent development, arising from the synthetic-biomimetic-peptide and "growth factor serum" trend in cosmetic skincare and haircare. The "sh-" prefix denotes a synthetic human sequence; this particular peptide is produced by expressing the human follistatin gene in *Nicotiana benthamiana* (a tobacco relative used as a plant bioreactor). It gained mainstream visibility as the headline peptide in a heavily publicized multi-peptide scalp serum.
The standing of the evidence has not been settled by later work. The original injection finding has not been replaced or overturned, but it also has not been replicated in large trials, and it has not been shown to transfer to topical application. The honest current position is that the mechanistic rationale is real and the early injection signal is intriguing, while topical efficacy remains unproven.
## Expected Benefits
All benefits below concern scalp application aimed at hair regrowth, the focus of this review.
### High 🟩 🟩 🟩
(No benefits qualify for a High evidence grade. No high-quality human trials of topical Sh-Polypeptide-86 for hair exist.)
### Medium 🟩 🟩
(No benefits qualify for a Medium evidence grade.)
### Low 🟩
#### Increased Follicle Density and Hair-Shaft Thickness (via Follistatin Activity) ⚠️ Conflicted
The core proposed benefit is more and thicker hairs through removal of activin/myostatin braking on the follicle. The only direct human evidence is a single small phase 1 study (Zimber et al., 2011, 26 men) in which an *injected* follistatin-and-Wnt mixture increased follicle density and shaft thickness, with effects reported to last up to a year after one treatment. A conflict of interest applies here: this pivotal study was conducted and funded by Histogen Inc., the company developing the injected Hair Stimulating Complex, so the only positive human signal originates from a party with a direct financial stake in a favorable result; the topical serums that now invoke this finding are likewise commercial products (most prominently the Blueprint line) whose vendors benefit from the efficacy claim. The evidence is conflicted for the topical context: the positive signal exists but comes from injection of a multi-component product, not from topical Sh-Polypeptide-86 alone, and independent reviewers note that no preclinical or clinical efficacy data exist for the topical ingredient and that delivery of a large protein across skin is unproven. The grade is Low, not higher, because the human data are single-study, small, injected, confounded by co-administered growth factors, and sponsored by an interested commercial party.
**Magnitude:** In the 2011 injection study, modest increases in follicle density and hair-shaft thickness were reported in 26 men; no comparable magnitude has been demonstrated for the topical ingredient.
### Speculative 🟨
#### Anagen Phase Extension and Reactivation of Dormant Follicles
Marketing positions the peptide as reactivating resting follicles and prolonging the growth phase. Mechanistically this is plausible from mouse follistatin/activin biology, where follistatin promotes follicle development and counters the growth-retarding effect of activin. However, no controlled human study has demonstrated anagen extension from topical Sh-Polypeptide-86; the basis is mechanistic extrapolation from animal models and from the injection study, making it speculative for the topical product.
#### Synergy Within Multi-Peptide Growth-Factor Serums
Sh-Polypeptide-86 is almost always combined with other biomimetic peptides — peptides that mimic the body's growth-signaling proteins such as VEGF (vascular endothelial growth factor, which builds blood vessels), IGF/hGH (insulin-like growth factor and human growth hormone, which drive tissue growth), PDGF (platelet-derived growth factor, which spurs cell proliferation and repair), EGF (epidermal growth factor, which stimulates skin cell growth), and copper tripeptide GHK (a small skin-repair peptide) — together with delivery aids such as nanoliposomes. Proponents argue the combination delivers complementary pro-angiogenic and pro-proliferative signals to the follicle. This is mechanistically coherent but entirely speculative as applied: no controlled trial isolates Sh-Polypeptide-86's contribution, and the finished serums have not been tested in published clinical studies.
## Benefit-Modifying Factors
* **Genetic polymorphisms:** No validated pharmacogenetic markers govern response to topical Sh-Polypeptide-86 specifically. More broadly, androgen-receptor and 5-alpha-reductase genetics drive pattern hair loss severity and may set the ceiling on what any single follicle-stimulating agent can achieve; individuals with strong genetic miniaturization may respond less to a brake-removal strategy.
* **Baseline biomarker levels:** Endogenous scalp myostatin/activin tone and local follistatin levels are not routinely measurable and have no standard assay, so baseline status cannot currently be used to predict response. Baseline follicle miniaturization (caliber on trichoscopy) is the most practical proxy for residual responsiveness.
* **Sex-based differences:** The only direct human evidence (injection study) was in men with pattern hair loss; female pattern hair loss has different hormonal drivers and was not studied, so any benefit in women is unestablished.
* **Pre-existing health conditions:** Scalp conditions that disrupt the skin barrier or follicle (active inflammation, scarring alopecia) would be expected to reduce both delivery and the pool of viable follicles available to respond.
* **Age-related considerations:** Older individuals at the upper end of the target range tend to have a higher proportion of permanently miniaturized or lost follicles and thinner skin; a follicle-stimulating peptide can only act on follicles that still exist, so advanced loss limits achievable benefit.
## Potential Risks & Side Effects
### High 🟥 🟥 🟥
(No risks qualify for a High evidence grade.)
### Medium 🟥 🟥
(No risks qualify for a Medium evidence grade.)
### Low 🟥
#### Local Skin and Scalp Irritation
As with most topical serums, the most realistic adverse effects are local: irritation, redness, itching, or contact sensitivity. These are usually driven by the full formulation (solvents, preservatives, penetration enhancers, and other actives such as salicylic acid and caffeine) rather than the peptide itself. The evidence basis is general cosmetic experience and the formulation contents rather than ingredient-specific reports.
**Magnitude:** Not quantified in available studies.
### Speculative 🟨
#### Theoretical Local Growth-Signal Modulation
Because follistatin alters TGF-β-family signaling involved in cell growth, a theoretical concern is unintended local effects on tissue with chronic application. The basis is mechanistic only; injected follistatin gene therapy and the 2011 scalp-injection study reported no such adverse signal, and there are no reports tied to the topical cosmetic ingredient. It is listed as speculative for completeness, not because of demonstrated harm.
#### Unknown Long-Term Topical Safety
The finished serums containing Sh-Polypeptide-86 are recent and have not been subjected to published long-term safety studies. The basis for any concern is the absence of data rather than a specific signal; the favorable safety record of follistatin in injection and gene-therapy settings is reassuring but does not formally transfer to chronic topical use.
## Risk-Modifying Factors
* **Genetic polymorphisms:** No genetic variants are established to modify the safety of topical Sh-Polypeptide-86. General atopic or contact-allergy predisposition (e.g., filaggrin-related barrier defects) increases the likelihood of irritation from any topical formulation.
* **Baseline biomarker levels:** No biomarker predicts adverse response to this peptide. Baseline barrier integrity (visible eczema, dermatitis) is the practical factor that raises irritation risk.
* **Sex-based differences:** No sex-specific safety differences have been characterized for topical application; the injection literature is predominantly male.
* **Pre-existing health conditions:** Active scalp dermatitis, psoriasis, open lesions, or seborrheic dermatitis raise the risk of irritation and increased absorption from any scalp serum.
* **Age-related considerations:** Thinner, more reactive skin in older individuals at the upper end of the target range may increase susceptibility to local irritation from the overall formulation.
## Key Interactions & Contraindications
* **Prescription drug interactions:** No documented systemic drug interactions exist for topical Sh-Polypeptide-86; meaningful systemic absorption of an intact large protein across intact skin is not expected. Concurrent prescription topicals applied to the same area (e.g., topical minoxidil, topical corticosteroids) have not been studied in combination.
* **Over-the-counter medication interactions:** No specific OTC interactions are documented. Co-applied OTC scalp products containing exfoliants or alcohols could increase irritation from the combined regimen.
* **Supplement interactions:** No documented supplement interactions. Oral supplements marketed to "boost follistatin" or inhibit myostatin have not been studied alongside the topical peptide.
* **Additive-effect agents:** Other topical follicle-stimulating actives commonly co-formulated or co-used — minoxidil, copper tripeptide-1 (GHK-Cu), caffeine, adenosine, and procapil-type peptides — act on overlapping pro-growth pathways; their combined effect with Sh-Polypeptide-86 is additive in intent but unquantified, and stacking multiple irritant-prone topicals raises cumulative irritation risk.
* **Other interventions:** Combination with microneedling is frequently promoted to improve delivery of large peptides; while microneedling can plausibly raise penetration, it also increases absorption of all co-applied ingredients and the associated irritation risk.
* **Populations who should avoid this intervention:** Individuals with active scalp dermatitis, broken or inflamed scalp skin, scarring alopecia, or known allergy to any formulation component; and, on a precautionary basis given the absence of data, pregnant or breastfeeding individuals.
Each interaction above is best characterized as **caution / monitor** rather than absolute contraindication, the main clinical consequence being local irritation or unverified added benefit. The principal mitigating actions are patch testing before full use, separating the timing of multiple irritant topicals, and discontinuing if irritation develops.
## Risk Mitigation Strategies
* **Patch test before first full application:** Apply a small amount to a discreet area of skin and wait 48 hours to check for redness, itching, or rash before applying to the whole scalp — this mitigates contact irritation and allergic reaction from the peptide or, more likely, the full formulation.
* **Start with reduced frequency:** Begin with application every other day for the first 1–2 weeks rather than the full recommended cadence, increasing only if well tolerated — this limits cumulative irritation, the main realistic adverse effect.
* **Avoid broken or inflamed scalp skin:** Do not apply over active dermatitis, open lesions, or freshly microneedled skin until healed — this prevents heightened irritation and uncontrolled increased absorption.
* **Separate the timing of multiple topicals:** If combining with other scalp actives (e.g., minoxidil, exfoliating treatments), space applications by several hours — this reduces the additive irritation risk identified in the Interactions section.
* **Discontinue on persistent irritation:** Stop use if redness, itching, or flaking persists beyond a few days — this prevents progression to a contact dermatitis from the overall serum.
## Therapeutic Protocol
* **Standard approach (topical serum):** As marketed by the leading commercial products, Sh-Polypeptide-86 is delivered as one component of a multi-peptide scalp serum, typically applied once or twice daily to a clean, dry scalp and left on, with manufacturers stating that visible scalp and hair changes require at least about four months of consistent use. There is no established standalone topical protocol for the isolated peptide.
* **Competing approach (injection / procedural, integrative clinics):** The only human efficacy evidence used injection of a follistatin-containing growth-factor mixture into the scalp (Zimber et al., 2011), an approach pursued in some integrative and cosmetic-dermatology settings rather than at home; this is presented as an alternative delivery route, not as the default. Neither route is framed here as superior, since the injection evidence is single-study and the topical evidence is absent.
* **Originators cited:** The injection-based follistatin/Wnt approach traces to the Histogen wound-healing-derived "hair stimulating complex" program behind the 2011 trial; the topical multi-peptide serum format was popularized by the Blueprint (Bryan Johnson) haircare products, which is where Sh-Polypeptide-86 became publicly prominent.
* **Best time of day:** No chronobiology data exist for this peptide. Practically, application is timed to a clean dry scalp (commonly morning and/or evening) so the serum is not immediately washed off.
* **Half-life consideration (protein, not small molecule):** Endogenous follistatin has a very short circulating half-life (minutes to about an hour), and topically applied protein is expected to be degraded by local skin proteases; this is why repeated, sustained application — rather than a single dose — is the assumed requirement for any topical effect.
* **Single vs. split dosing:** Because the peptide is leave-on and locally acting, "dosing" is a matter of application frequency rather than systemic split dosing; once- or twice-daily leave-on application is the practical pattern.
* **Genetic polymorphisms:** No pharmacogenetic variant guides dosing of this peptide. Androgen-pathway genetics influence overall pattern-hair-loss trajectory and may inform whether the peptide is used alongside an anti-androgen strategy, but do not change the peptide's application itself.
* **Sex-based differences:** Human evidence is male-only; no female-specific protocol exists, and the hormonal drivers of female pattern hair loss differ, so extrapolation of dosing to women is unsupported.
* **Age-related considerations:** Older users at the upper end of the target range have more thinning and barrier-compromised skin and fewer viable follicles; protocol expectations should be tempered accordingly, though application mechanics are unchanged.
* **Baseline biomarker levels:** No baseline lab governs use; trichoscopic follicle caliber is the most practical baseline measure of how much responsive follicle remains.
* **Pre-existing health conditions:** Scalp inflammation or scarring alopecia should be treated or excluded before starting, as they reduce both delivery and the pool of follicles available to respond.
## Discontinuation & Cycling
* **Lifelong vs. short-term:** Pattern hair loss is progressive, so any maintenance effect from a topical follicle-stimulating peptide would, like other topical hair treatments, be expected to require ongoing use; there is no evidence of a durable effect after stopping the topical product (the year-long durability reported in the 2011 study was for an injection, not the serum).
* **Withdrawal effects:** No withdrawal syndrome is known. The realistic outcome of stopping is gradual loss of any gains as the follicle returns to its untreated trajectory, mirroring the pattern seen when other topical hair treatments are discontinued.
* **Tapering:** No tapering protocol is needed or established; the peptide can be stopped without a taper, as there is no pharmacological dependence.
* **Cycling:** No evidence supports cycling to maintain efficacy. Because the proposed mechanism is continuous removal of growth-braking signals, continuous rather than cyclical use is the more coherent expectation, but this is unstudied.
## Sourcing and Quality
* **Form and identity:** Look for the INCI name (International Nomenclature of Cosmetic Ingredients, the standardized labeling system for cosmetic ingredient lists) "sh-Polypeptide-86" on the ingredient list; it is a synthetic/recombinant human follistatin sequence, typically produced by plant-based expression (*Nicotiana benthamiana*). It is a cosmetic ingredient, not an approved drug, so it carries no pharmaceutical purity grade.
* **Third-party testing:** Because finished serums are cosmetics rather than supplements or drugs, independent potency and purity verification is limited; prefer manufacturers that disclose the peptide concentration, provide a delivery rationale (e.g., encapsulation/liposomal system), and publish ingredient sourcing. Be skeptical of products that name the peptide prominently but disclose neither concentration nor any delivery strategy.
* **Reputable sources:** The most visible finished products are the Blueprint (Bryan Johnson) peptide hair serum and shampoo; compounding and cosmeceutical suppliers also offer the raw INCI ingredient. No brand has published clinical validation of the finished product, so brand selection rests on formulation transparency rather than proven efficacy.
* **Delivery is the decisive quality factor:** For a large protein, the formulation's penetration-enhancement strategy matters more than peptide identity; a serum with no credible delivery system is unlikely to get meaningful peptide to the follicle regardless of how much is listed.
* **Avoid grey-market injectables:** "Follistatin" sold as an injectable or as gene therapy outside regulated trials is a distinct and higher-risk category from the cosmetic topical peptide and should not be conflated with it.
## Practical Considerations
* **Time to effect:** Manufacturers state that scalp and hair changes take at least about four months of consistent use, consistent with the hair cycle; any honest expectation of visible change is measured in months, not weeks.
* **Common pitfalls:** Expecting drug-level results from a cosmetic; assuming a large protein automatically penetrates the scalp; conflating the injected 2011 study's results with the topical serum; and using the peptide in place of, rather than alongside, evidence-based options for those seeking maximal results.
* **Regulatory status:** Sh-Polypeptide-86 is regulated as a cosmetic ingredient, not as a drug; it has no approval for treating hair loss, and hair-regrowth claims for cosmetic peptides are not subject to drug-level efficacy review.
* **Cost and accessibility:** The branded multi-peptide serums are positioned at a premium price point relative to commodity hair treatments; the isolated ingredient is accessible to formulators but the finished consumer products are comparatively expensive for an unproven benefit.
* **Realistic framing:** For risk-aware optimizers, the peptide is best viewed as a low-risk, low-proven-benefit add-on rather than a primary intervention.
## Interaction with Foundational Habits
* **Sleep:** The interaction is **indirect**. There is no known direct effect of topical Sh-Polypeptide-86 on sleep, and no mechanism by which a locally acting scalp peptide would affect it. Sleep matters to hair only through general physiology (stress, recovery), so the practical consideration is simply that the peptide neither helps nor harms sleep.
* **Nutrition:** The interaction is **indirect**. No nutrient depletion or dietary requirement is associated with the topical peptide. Adequate protein, iron, and overall nutritional status are foundational for hair growth generally, so correcting deficiencies is a more impactful lever than the peptide; there is no specific food to include or avoid for the peptide itself.
* **Exercise:** The interaction is **indirect and potentially confounded**. Notably, follistatin is also released systemically with exercise as part of muscle-myostatin biology, but this is unrelated to topical scalp application; exercise will not augment a topical serum's local effect, and the topical serum has no effect on exercise. The practical point is to avoid attributing exercise-related changes to the serum.
* **Stress management:** The interaction is **indirect**. Chronic stress can worsen hair shedding through separate hormonal pathways; the topical peptide does not modulate cortisol or the stress response. Stress reduction is a complementary habit for hair generally but operates independently of this peptide.
## Monitoring Protocol & Defining Success
Because Sh-Polypeptide-86 is a topical cosmetic with negligible expected systemic absorption, laboratory monitoring is not driven by safety the way a systemic drug would be; monitoring is primarily about objectively tracking hair response and ruling out treatable contributors to hair loss before and during use.
Before starting, a baseline assessment is advised: standardized scalp photographs and, where available, trichoscopy to document follicle caliber, plus baseline labs to exclude common reversible contributors to hair loss (especially iron status and thyroid function). Ongoing monitoring is about consistency over time rather than frequent testing: repeat standardized photographs at roughly 4 weeks (baseline irritation check), 4 months (first realistic efficacy read-out), and then every 4–6 months, with labs rechecked only if baseline abnormalities were found or shedding changes.
| Biomarker | Optimal Functional Range | Why Measure It? | Context/Notes |
|-----------|--------------------------|-----------------|---------------|
| Ferritin (iron stores) | 50–100 ng/mL (functional target for hair) | Low iron stores drive diffuse hair shedding and blunt any treatment response | Conventional lab "normal" often starts at ~15–30 ng/mL, well below the hair-functional target; an acute-phase reactant, so interpret alongside inflammation markers; fasting not required |
| TSH | 0.5–2.5 mIU/L (functional) | Thyroid dysfunction is a common reversible cause of hair loss that can mimic or mask treatment effect | TSH (thyroid-stimulating hormone) reflects thyroid activity; conventional upper limit (~4–4.5 mIU/L) is higher than the functional target; best paired with free T4/free T3; morning draw preferred for consistency |
| Vitamin D, 25-OH | 40–60 ng/mL (functional) | Low vitamin D is associated with hair-cycle disturbances and follicle health | Conventional "sufficient" starts at ~30 ng/mL; fat-soluble, so timing/fasting not critical; pair with a baseline metabolic panel if supplementing high doses |
Qualitative markers of success or trouble are tracked alongside the photographs:
* Reduced daily shedding (hairs in brush, shower, or pillow)
* Visible new short regrowth (vellus-to-terminal transition) at the hairline or part
* Increased perceived density or scalp coverage in consistent lighting
* Improved hair-shaft thickness and manageability
* Absence of scalp irritation, redness, or flaking as a tolerability marker
## Emerging Research
Research relevant to Sh-Polypeptide-86 sits across two fronts — follistatin biology (mostly aimed at muscle and aging) and topical peptide delivery for hair — and includes work that could either strengthen or weaken the case.
* **Follistatin gene and plasmid therapy trials (systemic, not hair):** Several registered trials test follistatin delivery for muscle and aging conditions, establishing follistatin's human safety profile but not its hair efficacy. Examples include a completed phase 1 injectable follistatin plasmid gene-therapy study in frailty and aging ([NCT06411366](https://clinicaltrials.gov/study/NCT06411366), 43 participants) and a recruiting follistatin/klotho gene-therapy safety study in healthy adults ([NCT07285629](https://clinicaltrials.gov/study/NCT07285629), early phase 1, 30 participants). These could strengthen confidence in follistatin's safety while leaving the hair question open.
* **Earlier follistatin gene-transfer dystrophy trials:** Completed muscular-dystrophy gene-transfer studies ([NCT01519349](https://clinicaltrials.gov/study/NCT01519349), phase 1) contribute long-run human safety data for follistatin overexpression, indirectly reassuring for the cosmetic peptide but unrelated to scalp efficacy.
* **The unreplicated hair signal:** The pivotal human hair finding remains the single 2011 phase 1 injection study (Zimber et al., [PMID 22052313](https://pubmed.ncbi.nlm.nih.gov/22052313/)); the most decisive emerging need is an adequately powered, placebo-controlled replication — and, critically, a head-to-head test of *topical* versus injected delivery. Absence of such a trial is the single biggest weakness in the case.
* **Growth-factor and IGF-1 hair biology:** Reviews of growth-factor signaling in hair regeneration (e.g., Hsieh et al., 2025, [PMID 41020895](https://pubmed.ncbi.nlm.nih.gov/41020895/)) map the broader pathway space (IGF-1, VEGF, PDGF) in which follistatin's brake-removal sits and highlight delivery innovations (liposomal and exosome carriers) that could, if they translate, make large-protein topical delivery more credible — strengthening the rationale if they succeed and weakening it if they continue to fail.
* **Comparator evidence base:** Network meta-analysis of alopecia treatments (Mateos-Haro et al., 2023, [PMID 37870096](https://pubmed.ncbi.nlm.nih.gov/37870096/)) underscores how much of the hair-loss field rests on low-certainty evidence and how high the bar is for a new agent to demonstrate benefit — context that tempers expectations for an unproven cosmetic peptide.
## Conclusion
Sh-Polypeptide-86 is a lab-made copy of human follistatin, a natural protein that switches off other signals telling cells to stop growing. The idea behind using it on the scalp is appealing: by lifting these "stop-growing" brakes on hair follicles, it might wake resting follicles and lengthen the active growing phase, producing more and thicker hairs.
The reality is that the supporting evidence is thin and mostly indirect. The one piece of human data linking follistatin to hair comes from a single small study that injected it together with other growth signals — not the leave-on serum sold today — and it has never been repeated in a large trial. That study was run and paid for by the company developing the treatment, and the serums sold today are commercial products, so the few favorable findings come from parties with money at stake. Animal studies make the mechanism believable, but no controlled human study shows that the topical product actually works, and a real practical problem hangs over it: follistatin is a large protein, and large proteins struggle to pass through skin to reach the follicle at all.
On safety, the picture is reassuring at the level of local skin tolerance, with the main realistic downsides being irritation from the overall formulation; long-term topical safety is simply untested. The honest summary is that the rationale is plausible and the early signal is intriguing, while proof that the topical peptide regrows hair does not yet exist.
**[Top](#top) - [Benefits](#expected-benefits) - [Risks](#potential-risks--side-effects) - [Protocol](#therapeutic-protocol)**