Myrtol standardized is an essential oil derived from the Myrtle plant (Myrtus communis) and most commonly found in various herbal-based remedies for Sinusitis

Sinusitis

Sinusitis is inflammation of the paranasal sinuses, which may be due to infection, allergy, or autoimmune issues. Most cases are due to a viral infection and resolve over the course of 10 days...

 and other sinus congestions.

Myrtol standardized is a phytotherapeutic extract (distillate) consisting mainly of three monoterpenes: (+)α-pinene

Alpha-Pinene

α-Pinene is an organic compound of the terpene class, one of two isomers of pinene. It is an alkene and it contains a reactive four-membered ring. It is found in the oils of many species of many coniferous trees, notably the pine. It is also found in the essential oil of rosemary...

, d-limonene and 1,8-cineole (Aka. Eucalyptol, but not be confused with Eucalyptus oil

Eucalyptus oil

Eucalyptus oil is the generic name for distilled oil from the leaf of Eucalyptus, a genus of the plant family Myrtaceae native to Australia and cultivated worldwide. Eucalyptus oil has a history of wide application, as a pharmaceutical, antiseptic, repellent, flavouring, fragrance and industrial uses...

.) For example, in one product (Gelomyrtol forte) the ratio between distillates of Eucalyptol (Eukalyptus oil extract), D-limonene (lemon peel extract), and an esoteric 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.