Hair Regrowth Oil: A Narrative Review of the Published Evidence for Rosemary Oil, Peppermint Oil, Panax Ginseng, Castor Oil, Argan Oil, and Olive Oil

Hair loss and hair thinning are widely studied across dermatology, trichology, cosmetic science, pharmacology, and botanical medicine. The evidence for plant-derived ingredients is varied, with some ingredients supported by human clinical studies, while others are supported mainly by human hair-follicle research, animal models, in-vitro experiments, or evidence relating to scalp and hair-fibre condition.

This narrative literature review examines the published evidence relating to the six botanical ingredients used in Lustrao Hair Regrowth Oil:

(A) Rosemary oil
(B) Peppermint oil
(C) Panax ginseng
(D) Castor oil
(E) Argan oil
(F) Olive oil and olive-derived compounds

The review considers evidence across several areas relevant to hair growth and hair loss, including androgenetic alopecia, hair-follicle activity, dermal papilla cells, follicular cycling, anagen induction, growth-associated signalling pathways, inflammation, oxidative stress, scalp condition, hair-fibre strength, hydration, elasticity, and breakage.

For each ingredient, the review distinguishes between different levels of evidence, including human randomised controlled trials, human clinical and observational research, human hair-follicle and tissue studies, animal models, in-vitro and molecular research, and supporting evidence relating to scalp and hair quality. Individual studies are presented with their sample size or experimental scope, study design, principal findings, relevance to the ingredient, and important methodological limitations.

The published evidence is not uniform across the six ingredients. Rosemary oil has the clearest direct human clinical evidence in the current literature, including a randomized six-month comparison with 2% minoxidil in men with androgenetic alopecia. Peppermint oil has demonstrated hair-growth effects in a controlled animal model, including changes in follicle number, follicle depth, dermal thickness, and insulin-like growth factor-1 expression. Panax ginseng has a comparatively broad mechanistic literature, including studies involving cultured human hair follicles, human dermal papilla cells, specific ginsenosides, and pathways associated with follicular proliferation and the hair cycle.

Castor oil and argan oil have a different evidence profile, with research more strongly supporting roles in emollience, scalp condition, hydration, hair appearance, and fibre properties than direct follicular regrowth. Olive oil is also considered separately from olive-derived compounds such as oleuropein, for which experimental hair-growth evidence exists in human dermal papilla cells and animal models. Evidence involving an isolated olive-derived compound is not treated as direct clinical evidence for olive fruit oil.

The review does not treat evidence from animal or laboratory studies as equivalent to evidence from human clinical trials. It also does not assume that findings for an individual ingredient establish clinical efficacy for the finished Lustrao Hair Regrowth Oil. The purpose of the review is to organise the existing published evidence, identify the strongest findings for each ingredient, and describe the current limitations of the evidence base.

This document is a narrative literature review and secondary evidence synthesis prepared by Lustrao. It is not a new clinical trial and has not itself been peer reviewed as a journal publication. All findings discussed in the review are derived from previously published research and identified secondary literature.