Although essential oils have been used therapeutically for centuries, there is little published research on many of them. However, this is beginning to change as more scientific studies on essential oils are conducted around the world. Clinical studies are currently underway in Europe, Australia, Japan, India, the United States, and Canada. Many of these studies describe the remarkable healing properties of various oils.
According to a study by the National Cancer Institute : Many studies of essential oils have found that they have antibacterial effects when applied to the skin. Some essential oils have antiviral activity against the herpes simplex virus. Others have antifungal activity against certain vaginal and oropharyngeal fungal infections. In addition, studies in rats have shown that different essential oils can be calming or energizing. When rats were exposed to certain fragrances under stressful conditions, their behavior and immune responses were improved.
Eucalyptus oil is reported useful in many circumstances, especially for purulent and non-purulent respiratory problems, including Bronchitis, asthma, and COPD. Other plant oils may sometimes appear more microbiologically active; however, the combination of the safety of moderate doses of Eucalyptus Oil along with its broad-spectrum antimicrobial action (including against tuberculosis and MRSA) make it an attractive alternative to pharmaceuticals. Source : Alternative Medicine Review
For more research studies on the benefits of essential oil, please visit National Association for Holistic Aromatherapy official website for more research paper here.