Capillary oxygen therapy is rooted in the vascular physiology of the hair follicle and the biochemistry of mitochondrial oxidative phosphorylation. Vasodilatory actives — menthol (TRPM8 receptors), caffeine (PDE inhibition) and niacinamide (NAD⁺ precursor) — indirectly improve follicular oxygenation by increasing perifollicular microcirculation. Hairswiss analyzes the molecular mechanisms and scientific limits of these protocols.