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Phototoxicity + Essential Oils - What You Need To Know

We love essential oils - as most people do...but it's important to note that they are not always safe to use by themselves or in certain situations.  In this post we want to talk a bit about essential oil safety during the sunny summer months, and what essential oils can potentially cause phototoxic affects.


Phototoxicity is defined as "a reaction to a substance applied to the skin that occurs only in the presence of UV light in the UVA range".  A type of photosensitivity, phototoxicity happens when particular chemical plant constituents combine with DNA in the skin - causing a reaction when subjected to sun or UV light. 

This reaction can result in damaged dermal tissues + skin cell death, often displayed in first to third-degree burns, severe discoloration, edema (swelling), and in some cases even blistering. Phototoxic reactions can occur anywhere from 1-24 hours after initial UV light exposure and the effects can last up to 36 hours.




Most people have heard of citrus essential oils and their phototoxic profiles...but that doesn't mean that ALL citrus essential oils are going to cause phototoxic reactions.  These reactions are caused by a group of chemical constituents called "Furanocoumarins."  The higher to content of these chemicals, the higher they are on the phototoxicity scale.  However, Furanocoumarins are non-volatile chemical compounds and often are left behind during the process of steam distillation, meaning that a steam distilled lemon essential oil would be less likely to yield phototoxic results than cold pressed (or expressed) lemon essential oil.

Here is a list of essential oils known to contain high concentrations of Furanocoumarins and a list of substitutes considered to be safe to use:

 Known Phototoxic Essential Oils

Non-Phototoxic Essential Oils

Bergamot (Citrus bergamia) Furanocoumarin-free/bergapten-free Bergamot (Citrus bergamia)
Cold pressed (expressed) Lime (Citrus aurantifolia) Steam distilled Lime (Citrus aurantifolia)
Cold pressed (expressed) Lemon (Citrus limon) Steam distilled Lemon (Citrus limon)
Fig Leaf Absolute (ficus carica) Steam distilled Grapefruit (Citrus paradisi)
Lemon Verbena (aloysia triphylla) Lemon Leaf (Citrus limon)
Taget Essential Oil or Absolute (Tagetes minuta) Mandarin, Tangelo, or Tangerine (Citrus reticulata)
Rue (Ruta graveolens) Neroli (orange blossom)(Citrus x aurantium)
Mandarin Leaf (Citrus reticulata) Sweet/Blood Orange (Citrus sinensis)
Cumin (Cuminum cyminum) Petitgrain Bigarade (orange leaf) (Citrus x aurantium)
Angelica Root (Angelica archangelica) Yuzu (Citrus junos)
Cold pressed (expressed) Bitter Orange (Citrux x aurantium)
Cold pressed (expressed) Grapefruit (citrus paradisi)

*Chart taken from The Herbal Academy of New England website.



How to Use Phototoxic Essential Oils Safely

We've said a lot of scary stuff about essential oils with phototoxic capability in this post, but don't be afraid of them!  There are still safe ways to use them, and we're going to go through a few of our top methods.

The best way to avoid phototoxic results from these essential oils is to simply not use them topically, especially those with the strongest concentrations of Furanocoumarins.  Most of these essential oils are safe to use internally + by inhalation (such as essential oil diffusers, diffuser jewelry, aromatic mists).  It is also said that they are completely safe to use in topical products that will be totally washed off like hand-soaps and shampoos.

If you must use any of these potentially phototoxic essential oils topically for any reason, here are some tips to avoid harmful UV reactions:

1. If possible, first try to find an alternative non-phototoxic essential oil to replace the one you are using in your preparation.  For example, using a steam distilled grapefruit essential oil instead of a cold pressed (expressed) grapefruit essential oil will drastically reduce the phototoxic quality.

2. Be sure to cover skin wherever the essential oils have been applied.  However, know that some thin fabrics like sheer blouses and ultra light t-shirts will not block harmful UV rays from infiltrating the affected areas.

3.  Use these essential oils in your bedtime routine.  Although you may still want to cover the area well, typically using these oils before bed will give them time to lessen their phototoxic affects.

4. Dilute!  Proper dilution of essential oils is key to their use.  Even those that are not phototoxic can have dangerous affects when used without a carrier oil (i.e. extra virgin olive oil, prickly pear seed oil, rosehip seed oil).  Check the chart below taken from The Herbal Academy of New England + Clinical Aromatherapist Lea Harris for proper dilution of phototoxic essential oils:

 Phototoxic Essential Oil

Safe Percentage

Fig Leaf (Ficus carica)

no safe level

Lemon Verbena (Aloysia triphylla)

no safe level

Taget E.O. or Absolute (Tagetes minuta)


Rue (Ruta graveolens)


Mandarin Leaf (Citrus reticulata)


Bergamot (Citrus bergamia)


Cumin (Cuminum cyminum)


Cold pressed (expressed) Lime (Citrus x aurantifolia)


Angelica Root (Angelica archangelica)


Cold pressed (expressed) Bitter Orange (Citrus x aurantium)


Cold pressed (expressed) Lemon (Citrus x limon)


Cold pressed (expressed) Grapefruit (Citrus x paradisi)



According to Tisserand + Young's book "Essential Oil Safety, 2nd Edition," a good rule of thumb when using any citrus fruit oil or combination thereof is to use a maximum of 4 drops for every 30mL of carrier oil. (Tisserand and Young, 2014)


Essential oils are a lovely addition to an herbal home, and should be treated as such.  However, it is immensely important when working with these allies to take proper safety precautions.  Remember - if you are ever in doubt of your own ability to use any herbal preparation safely, always reach out to your local herbalist/aromatherapist/naturopath for guidance!



Essential Oil Safety, 2nd Edition, Tisserand and Young, 2014

Phototoxic Essential OIls, Using Essential Oils Safely, Lea Harris, CCA

The Truth About Phototoxic Essential Oils & How To Use Them Safely, The Herbal Academy of New England, Sherilyn Seigmand-Roach, M.Sc., C.C.A.

Phototoxic Essential Oils and What You Need To Know About Them, Edens Garden

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