Essential oils and photosensitization

The precautions for use of essential oils often refer tophotosensitizing essential oils, whichshould be avoided before exposure to the sun.

Definition of photosensitization

Photosensitization is a reaction of the skin to sunlight (UV rays) following the absorption or application of certain chemical or plant substances known as "photosensitizers". When the skin is exposed to sunlight or other sources of UV rays (tanning lamps p.ex.), these substances are activated and become irritating, sometimes even toxic.

Some essential oils may contain photosensitizing biochemical components

Photosensitizing reactions can be "phototoxic" or "photoallergic".

Photoallergy is a skin reaction without pigmentation, and most often occurs following the use of chemical UV protectors. Photoallergic reactions to essential oils are rare.

Phototoxic reactions are generally caused by furocoumarins and pyrocoumarins, which are often present in essential oils extracted from the peel of certain citrus fruits (botanical family Rutaceae). When exposed to UV rays, these essential oils can cause skin rashes, redness, brown or light spots (which are very difficult to remove), blisters or irreversible depigmentation.

There are exceptions. Although the following essential oils contain furocoumarins, they are not considered phototoxic due to their low percentage:

• Dill seed (Anethum graveolens)
• Angelica seed (Angelica archangelica)
• Caraway (Carum carvi)
• Parsley (Petroselinum crispum)

Some phototoxic essential oils can even cause epidermal mutations, leading to skin cancer. However, in the absence of UV rays, these same essential oils can, on the contrary, have cell-protecting effects!

Photosensitizing essential oils - precautions for use

It is recommended not to expose yourself to UV rays for at least 12 hours after applying or ingesting a photosensitizing essential oil or a preparation containing one. It is preferable to reserve its use for the evening, or to opt for its use in winter when you are less exposed to UV rays.
The IFRA (International Fragrance Association) recommends using the following maximum percentages in cosmetic products to limit phototoxic risks to the skin:

• Angelica root: 0.8%
• Bergamot: 0.4%
• Lime: 0.7% Limezest: 0.7% Lime: 0.7% Lime: 0.7% Lime: 0.7
• Lemon zest: 2% Cumin
• Cumin leaf: 0.4%
• Mandarin leaf: 0.17
• Bitter orange: 1.25% Grapefruit
• Grapefruit zest: 4% Tangerine
• Tagetes 0.01

Photosensitizing and phototoxic essential oils

• Angelica root (Angelica archangelica) +++
• Angelica root absolute
• Angelica root CO2 extract
• Bergamot pressed zest (Citrus aurantium) +++
• Celery (Apium graveolens)
• Lime, pressed zest (Citrus limetta) +++
• Lemon, pressed peel (Citrus limonum) +++
• Clementine, pressed zest
• Combava, pressed zest (Citrus hystrix)
• Cumin (Cuminum cyminum) +++
• Cumin absolute
• Cumin CO2 extract
• Khella (Ammni visnaga)
• Lovage (Levisticum officinalis)
• St. John's wort (Hypericum perforatum)
• Squeezed zest bitter orange (Citrus aurantium ssp aurantium) +++
• Grapefruit, pressed zest (Citrus paradisii) +++
• Parsnip (Pastinaca sativa)
• Rue (Ruta graveolens) +++
• Skimmia (Skimmialaureola)
• Tagetes (Tagetes minuta)

Non-phototoxic essential oils

The following essential oils are derived from rutaceae zest or leaves, but are not phototoxic:

• Bergamot without bergapten / furocoumarins (Citrus aurantium)
• Steam-distilled lemon (Citrus limonum)
• Lemon leaves
• Steam-distilled lime (Citrus limonum)
• Mandarin zest (Citrus reticulata)
• Sweet orange zest (Citrus sinensis)
• Sweet orange leaves
• Yuzu (Citrus junos)

Source: Essential Oil safety Tisserand/Young