A lab-made copy of a natural repair protein that signals follicle cells to multiply and builds blood supply around them. Early human evidence is modestly encouraging, but mainly as an add-on to other treatments rather than a stand-alone therapy. Side effects are mostly mild and local. Its independent value remains genuinely uncertain. (Full Review)

Protocol

Topical Serum

~3500 IU, 2× daily

With 1 mL of 5% minoxidil, on a dry scalp after cleansing

Clinic Delivery

Microneedling / mesotherapy

Intradermal sessions overcome poor skin penetration

Surgical Adjunct

Transplant graft support

Graft immersion plus post-operative topical application

Time to effect

Graft Survival

12 months

Transplant follicle survival assessed at one year

Density Gains

3–6 months

Density or caliber differences match the hair-cycle pace

Minoxidil Combo

6 months

Higher responder rate versus minoxidil alone

Benefits

Medium: Enhanced response when added to minoxidil, improved hair-transplant graft survival, additive density gains in platelet-rich-plasma combinations

Low: Increased hair shaft diameter and terminal-hair conversion, improved perifollicular blood supply

Speculative: New follicle formation and anagen induction, potential value in non-androgenetic hair loss

Contraindications

Active scalp malignancy or premalignant scalp lesions (squamous or basal cell carcinoma, actinic keratosis)

Known hypersensitivity to the recombinant protein or vehicle

Pregnancy or breastfeeding

Active scalp infection or inflammatory scalp disease

Key Interactions

Anticoagulants and antiplatelet drugs (warfarin, apixaban, clopidogrel, aspirin)

Topical exfoliants or retinoids

Risk & Side Effects

Medium: Application-site irritation

Low: Procedure-related effects from injection or microneedling, theoretical tumor-promotion and angiogenesis concern

Speculative: Immunogenicity to the recombinant protein, unwanted hair growth at application margins, unknown long-term safety of chronic use

Monitoring

Marker	Target	Why
Ferritin (iron stores)	40–70 ng/mL	Low iron stores impair regrowth and cause shedding
Vitamin D (25-OH)	40–60 ng/mL	Deficiency is linked to hair thinning and follicle cycling
TSH	0.5–2.5 mIU/L	Thyroid dysfunction causes diffuse hair loss
Serum zinc	90–120 µg/dL	Zinc deficiency contributes to shedding and weak hair
Testosterone / DHT (women with pattern loss)	Sex-specific reference, low-normal preferred	Screens for androgen excess driving miniaturization

Cadence: Baseline, 3, 6, and 12 months, then every 6–12 months for maintenance

Qualitative Assessment

Reduced daily shedding (fewer hairs on the pillow, in the shower drain, or on the comb)
Increased hair caliber and a fuller feel to existing hair
Visible new short regrowth ("baby hairs") along thinning zones or the hairline
Improved scalp coverage on standardized photographs
Subjective confidence in hair appearance

Sh-Polypeptide-1 for Hair Regrowth

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment