Peppermint oil is an inexpensive plant oil whose cooling, blood-flow-boosting effect has fueled hopes of thicker hair. That reputation rests on animal work alone; it has never been tested in people losing their hair, and it does nothing to address the hormone sensitivity driving most thinning. Best seen as a low-cost, low-risk experiment with an uncertain payoff. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Ferritin | ~40–70 ng/mL | Low iron stores are a common, correctable cause of shedding |
| Vitamin D (25-OH) | ~40–60 ng/mL | Deficiency is linked to increased shedding and pattern loss |
| TSH | ~1.0–2.0 mIU/L | Thyroid over- or under-activity causes diffuse hair loss |
| Zinc | ~90–120 µg/dL | Deficiency contributes to hair loss and poor regrowth |
| DHEA-S / total & free testosterone (women with pattern loss) | Age- and sex-specific reference | Androgen excess drives female pattern loss that a topical will not address |
Cadence: Baseline labs once before starting; reassess the hair at roughly 3–6 months, then every 6–12 months