A frequent question from newbie oil users is: how long will my essential oils last? It's a good question. Buying high quality oils may be a wise investment in your health but it is also a significant financial investment, so you want to make sure their therapeutic properties (aka benefits) last as long as possible, right?
In common with all natural products, the quality of essential oils will degrade over time due to the process of oxidation which occurs when the oils are exposed to oxygen, heat and light. Oxidation causes chemical changes in the oil which may not be noticable by you, unless you did a side-by-side comparison with a freshly opened bottle of oil, but those changes will cause degradation of the oil in terms of smell and efficacy.
Oxidation occurs even when essential oils are stored in optimum conditions, i.e. in a cool, dry and dark place and there is nothing that can be done to stop this process from kicking in eventually. But, the good news is, your oils will still last you a long time. Even citrus oils which degrade more quickly than other oils will remain in good condition for up to 12 months once opened and unopened, will remain fresh for several years. Although many essential oils share some of the same chemical constituents, each oil is unique and will degrade differently. Some oils, such as Sandalwood could remain in good condition for many years, while Lavender, if stored in ideal conditions, could outlive you. In this study, for example, French Lavender essential oil bottled in 1945, was found to be in relatively good condition in 2016. A total of 102 peaks (100% components) were identified, out of them 10 oxidized minor components (total 0.41%) were detected. That's not bad for 71 year-old Lavender!
It is worth noting, however, that it is not just the efficacy of essential oil that degrades over time. The actual chemical constituents can degrade into other, potentially toxic constituents that could cause skin sensitivities. All oils, including Lavender oil, differ in chemical composition depending on the numerous environmental factors they were subjected to, including soil composition, weather, storage, transportation, packaging, etc. The lavender essential oil in this study was dominated by linalool (40.8%), terpinen-4-ol (9.9%), α-terpineol (3.5%), linalyl acetate (16.4%), lavandulyl acetate (3.8%), and transcaryophyllene (2.2%). Linalool readily undergoes autooxidation to form cyclized molecule: furanoids and pyranoids. Furanoids are well known for their ability to cause photosensitivity (allergic reaction to sunlight).
How to store your oils: Now, you may not be able to store your oils with the same attention to detail as the French Lavender essential oil in the study, and nor do you need to. There are some precautions, however, that you can take to ensure your oils stay in good condition for years:
What are your best tips for storing essential oils?
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