Although topically applied essential oils have a long history of safe and effective use, some oils are believed to be more irritating than others. Many experts will agree that for many oils, it’s not so much the oil itself but the oxidized byproducts thereof that are commonly irritating to the skin. This occurs when essential oils are improperly produced or stored.
Though the oils are remarkably stable without oxygen exposure (such as when a bottle is unopened), they can oxidize if the oil is stored without a lid, if stored in a half-empty bottle for a long period of time, or if stored at a high temperature for an extended period of time.
Limonene and linalool are monoterpene molecules that are present in many essential oils. Citrus oils have high amounts of limonene, and Lavender, Clary Sage, Basil, Cilantro, and Coriander have high amounts of linalool.
An international consortium of researchers from Australia, Denmark, Singapore, Spain, Sweden, and the United Kingdom studied the effects of oxidized limonene and oxidized linalool on the skin. Of 2,900 participants who had previously been diagnosed with contact dermatitis, 281 (9.7 percent) reacted to the oxidized compounds. Of these, 25 percent had reactions to both compounds, while 29 percent only reacted to oxidized R-limonene and 46 percent only reacted to oxidized linalool. This suggests a specificity of reactions to oxidized compounds. Other organizations, such as the International Fragrance Association (IFRA), recognize this problem and encourage oil users to avoid oxidation of their limonene- and linalool-rich oils.
As reported in this study, the oxidized versions of limonene and linalool essential oils may be irritating to the skin. However, it is important to note that such reactions are most likely to occur in a relatively small percentage of highly susceptible individuals, and that the reactions appear to be dependent on the specific individual.
How can you ensure your oils’ safety? doTERRA essential oils are very stable and can be used for years if stored properly. Our oils will maintain their purity during shipment because of our strict packaging procedures, which prevents outside air from entering the product and reacting with the essential oil. However, after opening a bottle of essential oil, we recommend that you store it at room temperature or below, and away from places where it will be exposed to high temperatures or direct sunlight (such as in the car, a window sill, above a stove, etc.).
doTERRA Science blog articles are based on a variety of scientific sources. Many of the referenced studies are preliminary and further research is needed to gain greater understanding of the findings. Some articles offer multiple views on general health topics and are not the official position of doTERRA. Consult your healthcare provider before making changes to diet or exercise.