Eucalyptus oil is a favorite in aromatherapy, admired for its soothing menthol scent. Centuries ago eucalyptus trees were thought to cleanse the air, their leaves would be crushed up and used to fight infection and relieve muscular pain. Today, eucalyptus is still recognized for its medicinal properties, found in a many cough and cold formulas, vapor rubs, and more. It is also wonderful used in a diffuser or vaporizer to help freshen the air and re-energize the body.