A lab-made copy of a natural repair protein, used in scalp serums to coax resting follicles back into active growth. Animal studies are promising, but no human trials show scalp regrowth, and the one human lab study pointed the other way. Short-term topical use appears well tolerated; overall it remains experimental and largely unproven. (Full Review)

Protocol

Form

Topical serum

Minor active, usually within a multi-peptide "growth factor" complex

Frequency

Once–twice daily

Applied to a clean, dry scalp; split dosing maintains contact time

Delivery route

Topical, microneedling, or injectable

None established as superior; finished cosmetic serums preferred over injectables

Time to effect

First assessment

3 months

Earliest realistic point to judge any response

Full assessment

6 months

Standardized re-evaluation of the hair response

Ongoing review

Every 6–12 months

If continued; change cannot appear sooner

Benefits

Low: Accelerated hair regrowth; follicle stem cell activation; perifollicular angiogenesis support

Speculative: Adjunct to follicle-injury procedures; anti-inflammatory support of the follicle niche

Contraindications

Active or recent malignancy

Pregnancy or breastfeeding

Known allergy to the peptide or serum components

Active scalp infection or open wounds

Injectable TB-500 in competitive athletes (WADA-prohibited)

Key Interactions

Systemic anticoagulants (warfarin, apixaban), injected forms only

Minoxidil, other synthetic-human peptides, copper tripeptide (GHK-Cu), PRP

Microneedling

Risk & Side Effects

Low: Application-site irritation and contact dermatitis

Speculative: Pro-angiogenic/tumor-microenvironment concern; unknown percutaneous absorption and systemic exposure; contamination and purity risk in injectable or compounded products

Monitoring

Marker	Target	Why
Ferritin	40–70 ng/mL	Low iron stores suppress the follicle growth phase
Vitamin D (25-hydroxy)	40–60 ng/mL	Supports normal follicle cycling
TSH	0.5–2.0 mIU/L	Both under- and over-active thyroid cause hair shedding
Zinc (plasma)	90–120 µg/dL	Cofactor for follicle protein synthesis; deficiency causes shedding

Cadence: Baseline, then 3 and 6 months, then every 6–12 months if continued

Qualitative Assessment

Reduced daily shedding (fewer hairs on the pillow or in the shower)
Increased perceived density and scalp coverage on matched photographs
Improved hair caliber (finer, wispy hairs thickening) on trichoscopy
Subjective confidence in appearance, tracked over months

sh-Oligopeptide-4 for Hair Regrowth

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment