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18 October 2021 / Caitlin Devlin

Understanding phototoxicity in essential oils

Get to grips with furocoumarins, what they are, what they do, and how to use furocoumarin-containing oils safely.

Understanding phototoxicity in essential oils

You may have heard that some oils can cause phototoxic or photosensitive reactions – but what exactly does this mean, and how can we prevent it?

Phototoxicity, whilst it may sound intimidating, is very easy to avoid. These days we have a very good understanding of which oils give us phototoxic reactions and why this occurs, and it’s not difficult to adjust your use of essential oils and limit the risk. However, it’s still crucial to educate yourself properly on this topic in order to get the best possible results from natural products.

What is phototoxicity?

If you have engaged with aromatherapy in the past, then it’s likely you will have come across the word ‘furocoumarins’, particularly in association with citrus oils. Furocoumarins are a group of substances that bind to the DNA in skin cells. Upon exposure to the UV rays in direct sunlight, or the UV light of tanning beds, they react in a way that causes the body’s immune system to see the furocoumarins as invaders. In response, the immune system initiates an allergic reaction which is often severe and damages skin cells.

The effects of this sun exposure can be delayed by up to thirty-six to seventy-two hours, but eventually furocoumarins can cause discolouration that lasts for months, among other allergy-like symptoms.

 

What does a phototoxic reaction look like?

Phototoxic reactions can often imitate severe sunburns. They can be characterised by symptoms such as a burning sensation, rashes, blisters, inflammation and/or darkening of the skin. In some rare cases they can even present as third degree burns.

Which oils are phototoxic?

Here are some of the most common oils with phototoxic qualities:

  • Bergamot (cold pressed)
  • Bitter orange (cold pressed)
  • Grapefruit (cold pressed)
  • Lemon (cold pressed)
  • Lime (cold pressed)
  • Cumin

The majority of known phototoxic oils are citrus oils, particularly those that are extracted by cold pressing. This method of extraction involves placing the fruit in a device that mechanically pierces it in order to release the oil from the essential oil sacs. The essential oil is separated from the juice layer in a centrifuge. Heat is never applied to the oil – this is the key difference between cold pressed and steam distilled citrus oils.

Steam distilled oils, unlike cold pressed, are separated from the rest of the plant matter by the act of passing hot steam through an enclosed container. Since furocoumarins are less volatile than many other components in essential oils, they are left behind during this process. This is what makes steam distilled oils safe to apply to skin.

If you do want to apply a citrus oil to the skin – lemon oil, for example – then it is a good idea to look for an oil that described as steam-distilled or FCF (furocoumarin-free). It’s also usually very safe to apply oils made from parts of citrus plants other than the peel – for example, oils like neroli and petitgrain which are extracted from the leaves and flowers of citrus plants are not considered phototoxic. Even with non-phototoxic oils, however, you should always dilute with a carrier vegetable oil before applying to skin.

How do I treat a phototoxic reaction?

It’s easy to avoid a phototoxic reaction by not applying phototoxic oils to skin – however, some people like to apply cold-pressed oils to skin because of their more potent benefits. This is not recommended, but if you do apply oils containing furocoumarins directly to the skin then you should be sure to always consult a medical professional first, and to stay out of direct sunlight eighteen hours after application.

If you do have a phototoxic reaction, there are a few things that can help. For mild reactions, keeping the area moist and applying wet dressings can help to relieve discomfort. In more extreme cases, over the counter pain medications may be recommended, as well as steroid creams and antihistamines for redness and itching.

 

Does this mean I shouldn't buy cold pressed oils?

Not at all. Whilst it isn’t recommended to apply cold pressed oils to skin, there is a reason that cold pressing is still a common practice. Cold pressing citrus oils helps them to retain a higher level of potency than steam distilled oils. This typically gives them a stronger scent, which makes them perfect ingredients in candles and potpourri, and also gives them more powerful beneficial effects, making them ideal for diffusion. Many people also used cold pressed oils in home cleaners for their more potent antimicrobial properties.

In summary:

  • Phototoxic oils contain a high level of furocoumarins, which set off an allergic reaction when exposed to direct sunlight and damage skin cells.
  • Cold pressed citrus oils are usually phototoxic, but steam distilled citrus oils are usually safe to apply to skin.
  • If you apply cold pressed oils to skin and don’t stay out of direct sunlight for eighteen hours, you may have an adverse reaction, but there are things that can help with this.
  • Cold pressed oils are still valuable natural products with plenty of other uses.

Shop our citrus essential oils here.

 

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