Understanding Phototoxicity in Citrus Essential Oils

I am asked this question regarding citrus oils regularly so thought it would be great to shed some light on the topic. Phototoxicity refers to a reaction that occurs when certain substances are applied to the skin and cause irritation or burns upon exposure to sunlight. In the context of essential oils, this means that certain oils can cause adverse effects if they are used on the skin and then exposed to UV light.

Citrus Oils and Phototoxicity

Citrus essential oils are known for their refreshing scents and beneficial properties, but some are particularly prone to phototoxic reactions. The primary compounds responsible for phototoxicity in citrus oils are furocoumarins (also known as psoralens), which are more prevalent in certain oils.

Here’s a list of citrus essential oils that have tendancies to be phototoxic:

Lime (Citrus aurantiifolia)
Lime essential oil can also be phototoxic, primarily due to its high furocoumarin content.

Bergamot (Citrus bergamia)
Contains significant levels of bergaptene, a furocoumarin that makes it highly phototoxic. Bergamot essential oil is often available in a begaptene-free form to mitigate this risk.

Grapefruit (Citrus x paradisi)
Contains compounds that can cause phototoxic reactions, though it is less potent compared to bergamot or lemon.

Orange (Citrus sinensis)
Bitter orange (Citrus aurantium) is more likely to be phototoxic than sweet orange (Citrus sinensis), but both can have some level of phototoxicity depending on their specific composition.

Distilled vs Cold Pressed

The method of extraction, distillation or cold pressing, affects the chemical composition of essential oils and consequently their phototoxic potential:

Cold Pressed
Cold pressing is the method used to extract essential oils from citrus rinds. This process tends to retain higher levels of furocoumarins, making cold pressed citrus oils more likely to be phototoxic. For example, cold pressed bergamot oil typically contains more bergaptene compared to its distilled counterpart.

Distilled
Distillation is used to extract essential oils from plant materials using steam. Citrus oils that are distilled usually have lower furocoumarin levels and are less phototoxic.

Some practical advice for using Citrus Oils is to avoid UV or direct sun exposure if you are using citrus essential oils topically, particularly those that are cold pressed, for at least 12-24 hours.

Of course you can still use these beautiful oils for diffusing around the home and making other products and as always the dilution ratio is a key factor as well.