Keep your essential oils cool!
As the weather heats up in the Northern Hemisphere, make sure you are storing your essential oils appropriately.
Essential oils do oxidize eventually, but this happens more quickly with increased exposure to high temperatures, light and oxygen (air). To prolong their lifespan, keep essential oils in a cool, dark place, such as a refrigerator.
Oxidized essential oils are not only less effective, but can also present a higher risk of adverse reaction.
Heavier essential oils, such as Vetiver, Sandalwood and Patchouli, are the slowest to oxidize and may not need refrigeration.
For more on essential oil oxidation, go here or here.