Of the three oils in Woodsman, rosemary has the most substantial clinical record. Multiple peer-reviewed studies have tested it directly against standard hair loss treatments — not just in labs, but in controlled human trials. The results are meaningful enough that dermatologists have started recommending it as a credible alternative to pharmaceutical options.

The primary mechanisms are well understood. Rosemary oil improves microcirculation in the scalp, delivering more oxygen and nutrients to hair follicles. It also inhibits 5-alpha reductase, the enzyme that converts testosterone into DHT — the hormone most directly linked to androgenetic alopecia (male pattern hair loss). And it extends the anagen (active growth) phase of the hair cycle, meaning more of your hair spends more time growing rather than resting or shedding.

A 2024 review published in PMC examined the full body of evidence on natural alternatives for androgenetic alopecia. Among all the compounds reviewed — including peppermint oil, saw palmetto, green tea, and others — rosemary oil was identified as the standout, with the most consistent evidence for efficacy in treating male pattern hair loss.

We'll be straight with you: castor oil doesn't have the same depth of large-scale clinical trials as rosemary oil. That doesn't mean the evidence is weak — it means it's earlier-stage. The mechanistic research is compelling, the preclinical studies are positive, and the 2025 rosemary-castor oil trial above directly demonstrated meaningful results from the combination. But we won't overstate it.

What makes castor oil valuable is its core composition. It is roughly 85–90% ricinoleic acid — an omega-9 fatty acid with a unique chemical profile that operates on several pathways relevant to scalp health and hair growth. It's also rich in vitamin E, linoleic acid, and antioxidant compounds.

The honest summary on castor oil: the mechanisms are real and the early data is positive. Human clinical trials at scale are still limited. We use it in Woodsman because the combination evidence — particularly the 2025 rosemary-castor trial — supports it, and because a professional hairdresser with years of hands-on experience trusted it. That's not marketing. That's our actual position.

Cedarwood oil's role in Woodsman is primarily scalp-focused. Its key compounds — including cedrol, alpha-cedrene, and thujopsene — are known for their antifungal, antibacterial, and sebum-regulating properties. A balanced, healthy scalp is the foundation everything else builds on, and that's what cedarwood contributes.

Like castor oil, cedarwood warrants more large-scale human research in isolation. What the existing evidence supports clearly is its value as a scalp-health ingredient — and scalp health is the environment in which everything else either works or doesn't.