Myrtol standardized is an essential oil derived from Pinus spp (pine), Citrus aurantifolia (lime) and Eucalyptus globulus and most commonly found in various herbal-based remedies for sinus problems.
Myrtol standardized is a phytotherapeutic extract (distillate) consisting mainly of three monoterpenes: (+)-α-pinene, d-limonene and 1,8-cineole (as known as Eucalyptol, but not be confused with Eucalyptus oil). For example, in one product (Gelomyrtol forte) the ratio between distillates of Eucalyptol (eucalyptus oil extract), D-limonene (lemon peel extract), and an essential oil mixture of Myrtle and lemon, is (66:32:1:1). This can be somewhat confusing since the first two ingredients are part of the second two.
One systematic review of herbal medicines used for the treatment of rhinosinusitis concluded that the data from clinical study is insufficient to verify the effectiveness of Myrtol. A comprehensive multi-centre, randomised, double-blind, placebo-controlled clinical trial measuring the efficacy of Myrtol for treating acute bronchitis concluded that Myrtol is a statistically significantly superior to placebo in treating acute bronchitis.