As mentioned in our previous writings, essential oils are wonderful to help support the mind, body, and spirit, but they are not without contraindications. We need to be aware of some of the chemistry of essential oils, as that can help us understand whether the oil is safe to use or not. You’ve probably heard things like “all citrus oils are phototoxic essential oils” or “oxygen is not good for your oils,” but what do these statements mean, are they true, and how do we learn more about them?
What Do We Mean By Phototoxic Essential Oils
Some essential oils contain chemical constituents that react with ultraviolet light. These can irritate the skin, causing rashes and burns. For example, the molecules called furanocoumarins (FC) are mainly found in citrus oils. These usually happen when an oil has been made by pressing the oil from a citrus peel.
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Phototoxic Essential Oils
This reliable list says, if you buy them, know that they are most certainly going to be phototoxic essential oils.
- Angelica Root Essential Oil
- Bergamot Essential Oil (Cold Pressed)
- Bitter Orange Essential Oil (Cold Pressed)
- Grapefruit Essential Oil (Cold Pressed)
- Lemon Essential Oil (Cold Pressed)
- Lime Essential Oil (Cold Pressed)
- Mandarin Leaf Essential Oil
- Opopanax Essential Oil
- Rue Essential Oil
- Tagetes Essential Oil
So, we might say that all citruses are phototoxic essential oils, which is quite a safe way to look at it if you are a beginner. But if we explore it further, there are several non-phototoxic essential oils derived from citrus plants.
Which Citrus Essential Oils are NOT Phototoxic
- Bergamot FCF Essential Oil (FCF Has the Bergaptene/Furanocoumarins Removed)
- Bergamot Essential Oil (Steam Distilled)
- Blood Orange Essential Oil (Cold Pressed or Steam Distilled)
- Lemon Essential Oil (Steam Distilled)
- Lime Essential Oil (Steam Distilled)
- Mandarin Essential Oil (Cold Pressed or Steam Distilled)
- Sweet Orange Essential Oil (Cold Pressed or Steam Distilled)
- Petitgrain Essential Oil
- Tangerine Essential Oil (Cold Pressed or Steam Distilled)
- Yuzu Essential Oil (Cold Pressed or Steam Distilled)
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Are Phototoxic Essential Oils Always Phototoxic
To make things even more complicated, it’s not necessarily that there are furocoumarins in a particular oil but also how many of them there are. The quantity tends to be the problem, so sometimes, an oil may or may not be phototoxic based on the chemistry of this year’s crop.
Luckily, these are not commonly used essential oils.
Sometimes Phototoxic Essential Oils
- Clementine Essential Oil (Cold Pressed)
- Angelica Root Absolute
- Angelica Root CO2Celery Leaf Essential Oil
- Celery Seed Absolute
- Cumin Seed Absolute
- Cumin Seed CO2
- Parsnip Essential Oil
Please note that this is not a complete list of all phototoxic essential oils. Please refer to Essential Oil Safety by Tisserand and Young for a full and comprehensive list.
How Do Oxidation Cause Phototoxic Essential Oils
Oxidation is the chemical reaction that occurs when a substance comes into contact with oxygen, heat, light, or another oxidizing substance. This chemical reaction degrades the essential oils’ aromatic and therapeutic properties. Strangely, various chemical groups degrade differently. Again, we worry about citruses here since their lovely uplifting natures come from monoterpenes. Monoterpenes are tiny things that degrade very quickly, leading to oxidization. If you use oxidized oils, it can result in irritation or sensitization. This means the oils can leave your skin with rashes, burns, or blisters.
To reduce oxidation, we advise keeping your oils stored in cool, dark places, away from direct sunlight. Also, ensure the lids are kept on tightly, and make sure you don’t store them in plastic containers.
In summing up, using phototoxic essential oils can lead to skin burns. In addition, not storing your oils away from heat, light, and oxygen can lead them to degrade more quickly and make them not as effective. This can also lead to them causing skin irritations as well.
Using Phototoxic Essential Oils Safely
How you use phototoxic essential oils also needs to be taken into account. Sometimes, it doesn’t even matter if they are phototoxic essential oils because the way you use them might render that obsolete.
Tisserand states, "There is generally no phototoxic risk if the oils are used in a product that is either not applied to the body or is washed off the skin, such as shampoo, bath preparation, or soap. However, essential oils can adhere to the skin if used in a sauna or steam inhalation. There is no risk if the skin to which the oils are applied is covered in such a way as to prevent UV rays from reaching them."
Tisserand also recommends that "skin treated with phototoxic oils at levels higher than those maximum use levels, should not be exposed to UV light for 12-18 hours."
Practically, that means using the oils in the evening before you go to bed or ensuring your skin remains covered throughout the day if you have used them in the morning.
Likewise, the risk of phototoxicity is negated if you use very small oil dilutions. Bergamot, for example, does not carry a risk of phototoxicity at dilutions below 0.4%. So, one drop in a tablespoon of carrier oil will work much better than just a teaspoon.
Oils can also be perfectly stable, but then risk photosensitivity as the oil begins to oxidize.
Tisserand, R and Young, R (2014). Essential Oil Safety, Second Edition. Churchill Livingstone Elsevier, UK.