Major Eucalyptus Oil Components

Possessing a distinct and easily recognizable medicinal aroma, many over-the-counter cold remedies and oral care products such as Listerine mouthwash utilize eucalyptus oil. Aromatherapist Patricia Davis writes that eucalyptus oil has antibacterial and antiviral properties while Medline Plus, a publication of the National Institutes for Health, says eucalyptus oil also works as an expectorant--it helps clear out mucus from the lungs. According to Cornell University, there are over 500 types of eucalyptus species and the major component of each varies.

Blue Gum Eucalyptus

Distilling the blue gum tree's partially dried leaves yields colorless essential oil with a strong odor. Eucalyptus oil from this tree consists of 70 to 95 percent cineol, according to Cornell University. In her book, "The Illustrated Encyclopedia of Essential Oils," essential oil therapist and author Julie Lawless says this oil's other major components include pinene, limonene, cymene, phellandrene and terpinene. Julie Lawless recommends this oil to treat various respiratory infections, sinus troubles and colds.

Broad-leaved Peppermint Eucalyptus

This species of eucalyptus also comes from distillation of the tree's leaves. While aromatherapists utilize blue gum eucalyptus for many medicinal purposes, this particular type finds more use in deodorants, mouthwashes and in veterinary practices, says Julie Lawless. The main components include piperitone at 40 to 50 percent and phellandrene at 20 to 30 percent. Other components include campene, cymene and terpinene.

Lemon-scented Eucalyptus

While it has anti-fungal, antiseptic and antibacterial properties, lemon-scented eucalyptus oil frequently gets employed as a bug repellent. Citronellal makes up the majority of this oil--Julie Lawless says citronella makes up 80 to 95 percent of this oil, while Cornell University lists it at about 60 percent of the total oil. Other major components include geraniol and pinene.