Eucalyptus oils are comprised of more than 100 different compounds. While many of these natural compounds have their own unique attributes their effectiveness may be greatly enhanced when they combine synergistically to produce superior therapeutic or other outcomes.
Crude (single distilled) eucalyptus oils sometimes contain a greater number of compounds in different quantities than after the eucalyptus oils have been rectified (double distilled). For instance eucalyptus globulus oil is made up of about 60% cineole and 40% many other compounds. After rectification it contains 80% cineole and only 20% of all other compounds. This means 20% of other compounds have been siphoned off during the second distillation. The result is the crude oil may have a different or broader range of activities than the refined oil.
All pharmaceutical grade eucalyptus oils have to comply with the specifications set out in the various pharmacopoeias. General specifications and limitations are below:
Specifications BP: Eucalyptus Oil
Range – Limit
a(alpha) – pinene
Trace to 9%
b(beta) – pinene
Less than 1.5%
Less than 1.5%
d(delta) – limonene
Trace to 12%
At least 70%
Less than 0.1%
Less than 0.3%
Crude (single distilled) eucalyptus oils sometimes do not comply with these specifications. The main reason is that crude eucalyptus oil can contain isovaleraldehydes which have an unpleasant odour and a cough provoking vapour. The principal constituent of pharmaceutical grade eucalyptus oils is 1,8-cineole (eucalyptol) which must comprise at least 70% of the contents.
All eucalyptus oils are composed of complex mixtures of volatile organic compounds. The main group of constituents of eucalyptus oil are monoterpenes. They have a lower boiling point and are less polar than sesquiterpenes which are the other main group of components of eucalyptus oils. Monoterpenes and their oxygenated derivatives include alcohols, aldehydes, ethers (oxides), hydrocarbons, aromatic hydrocarbons and phenols. Sesquiterpenes which have higher boiling points are in the form of alcohols or hydrocarbons in eucalyptus oils.
A brief outline of the major constituents of pharmaceutical BP grade eucalyptus oil, together with their properties and uses follows.
1. 1,8-cineole (Eucalyptol)
- A monocyclic mono terpene ether (oxide). A colourless liquid with a light fresh eucalyptus fragrance and a spicy clean cooling taste
- Antibacterial, cough suppressant, expectorant, nasal decongestant and a respiratory anti-inflammatory
- Also a flavour and fragrance and a strong solvent and penetrating oil
- A pharmaceutical grade eucalyptus oil must contain 70% or more 1,8-cineole
2. a(alpha) – pinene
- Bicyclic monoterpene hydrocarbon
- Dry woody, resinous-piney odour used in flavours and perfumery
- Mildly antibacterial, anti-inflammatory
- Disinfectant and deodorant
- A strong natural solvent
- A pharmaceutical grade eucalyptus oil may contain up to 9% a(alpha)-pinene
3. d(delta) - limonene
- Monocyclic monoterpene hydrocarbon
- Odour of orange-citrus
- Mildly antibacterial
- A strong solvent for removal of oil and grease
- Used in cleaning products such as hand cleaners
- Pure limonene oxidises readily and is a skin and respiratory irritant
- Stable as a constituent of eucalyptus oil
- A pharmaceutical grade eucalyptus oil may contain up to 12% d(delta)-Limonene
4. a(alpha) – terpineol
- Monocyclic monoterpene alcohol
- Lilac odour
- Strongly anti-bacterial
- Common ingredient in perfumes, cosmetics and flavours
5. p(para) – cymene
- Monocyclic monoterpene aromatic hydrocarbon
- Strong aromatic hydrocarbon odour
- Good anti-bacterial activity
- Widely used in soaps and preparations to help overcome undesirable odours
- Tricyclic monoterpene alcohol
- Colourless or pale yellow liquid.
- Herbaceous, peppery, woody odour
- Main constituent tea tree oil
- Anti-bacterial, anti-fungal and anti-inflammatory
7. Cuminal Aldehyde
- Colourless to yellowish oil liquid
- Strong persistent odour
- Acrid burning taste
- Strongly anti-bacterial
- Tricyclic sesquiterpene alcohol
- Sweet rose like odour
9. p(para) – isoproplyphenol (Australol) Phenol
- Very strong anti-bacterial
- Bicyclic sesquiterpene alcohol
- Mildly anti-bacterial
- Tricyclic sesquiterpene hydrocarbon
- Woody odour
- Some anti-bacterial and anti-fungal activity
- Pharmaceutical (for features, packaging and pricing information please click here)
- Commercial / Industrial (for features, packaging and pricing information please click here)
Pharmaceutical oil consists mainly of Eucalyptol. Eucalyptol is used in a range of products including mouth washes, medicated lozenges and nasal sprays.
Pharmaceutical grade eucalyptus oil contains a wide range of natural compounds with a broad spectrum of anti-bacterial activity. It is used in antiseptics, arthritis and sports muscular rubs, liniments, cough mixtures and in many other products.
Eucalyptus oil for commercial use is a lower cost alternative to pharmaceutical grade eucalyptus oil. It is a natural cleaner, freshener, disinfectant, sanitiser and deodoriser. A water soluble version is also available.
Eucalyptus oil for industrial use is an economical blend with a strong eucalyptus fragrance, especially for manufacturers to incorporate into their own formulations.
Special blends of eucalyptus oils and water soluble versions for specific purposes are also available.