A synthetic copy of a natural body signal that widens blood vessels and calms inflammation, sold in leave-on scalp serums for thinning hair. Its case rests entirely on plausibility — no controlled human study exists, and early lab work even hints it may end hair growth. An experimental, premium-priced add-on with modest irritation risk and unproven benefit. (Full Review)

Protocol

Dose

A few drops of serum

Applied over thinning areas and massaged in gently

Frequency

Once or twice daily

Morning and/or evening

Application

Clean, dry scalp

Leave-on, not rinsed off

Time to effect

Visible change

3–6 months

At least, with consistent daily use; matches the hair cycle

Benefits

Speculative: Improved follicle blood supply, reduced follicle inflammation, prolonged hair growth phase (conflicting evidence)

Contraindications

Known hypersensitivity to the peptide or serum excipients

Broken, inflamed, or lesion-bearing scalp skin

Pregnancy and breastfeeding

History of scalp skin cancer or pre-malignant scalp lesions

Key Interactions

Topical vasodilators (minoxidil)

Systemic vasodilators and blood-pressure drugs (sildenafil, nitrates, amlodipine)

5-alpha-reductase inhibitors (finasteride, dutasteride)

Topical retinoids and exfoliants (adapalene, glycolic acid)

Topical corticosteroids (hydrocortisone)

Other cosmetic peptides (GHK-Cu copper peptides, other sh-polypeptides) and niacinamide

Procedures (microneedling, derma-roller, platelet-rich plasma, low-level laser therapy)

Risk & Side Effects

Low: Application-site skin reactions

Speculative: Allergic contact sensitization, theoretical stimulation of unwanted cell growth, systemic effects from skin absorption

Monitoring

Marker	Target	Why
Ferritin	40–70 ng/mL (women); 50–150 ng/mL (men)	Low iron stores are a common, reversible cause of shedding
Vitamin D (25-hydroxyvitamin D)	40–60 ng/mL	Low vitamin D is linked to hair thinning and poor follicle cycling
TSH	1.0–2.0 mIU/L	Thyroid imbalance is a reversible cause of diffuse hair loss
Serum zinc	90–120 µg/dL	Zinc deficiency can trigger telogen shedding
DHEA-S and free testosterone	Lab- and sex-specific reference	Screens for hormone-driven pattern loss, especially in women

Cadence: Standardized photographs at 3 months, 6 months, then every 6 months; abnormal baseline blood markers rechecked after treatment, typically at 3 months

Qualitative Assessment

Reduced shedding: fewer hairs lost during washing and brushing
Visible density and coverage: improvement in standardized photographs at the part line and temples
Hair quality: subjective sense of thicker, stronger, or faster-growing hair
Scalp comfort: absence of irritation, redness, or itching

sh-Polypeptide-71 for Hair Regrowth

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment