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Some essential oils are phototoxic or photo sensitive.  Phototoxic essential should be used with care in aromatherapy.

Definition of Phototoxicity in Aromatherapy

Phototoxicity, also known as photo sensitivity, means that something is more responsive to light, due to the presence of a radiation-absorbing substance, such as sunlight; in humans, it is thought that the presence of the chemical element furanocoumarins is responsible for this reaction.  Certain essential oils contain furancoumarins and therefore increase the risk of phototoxicity, or a reaction such as sunburn.
Furanocoumarins in Essential Oils

Furanocoumarins are a close relative of coumarins, another chemical element present in the make-up of some essential oils.  The most notable example of a furanocoumarin in essential oils is bergaptene which is naturally found in the essential oil of bergamot (Citrus bergamia).  Bergaptene used to be added to sunscreen lotions to aid tanning, although this practice is no longer continued as it was attributed to sunburn to those who used it with sensitive skin or caused uneven tanning. 

Bergamot Essential Oil: Phototoxicity Studies

Bergamot (Citrus bergamia) is considered to be the most photo toxic essential oil; there are now some bergamot essential oils which are “bergaptene-free” to try to avoid the potential photo sensitivity risk.  Bergamot has been the focus of several scientific studies in the search to establish its “risk potential” when used for both aromatherapy and perfumery purposes.

Studies include Zaynoun S T, Johnson B E and Frain-Bell W (1977) – A study of Bergamot and its importance as a photo toxic agent and Pathak M A, Fitzpatrick T B (1959) – Relation of molecular configuration to the furocoumarins which increase the cutaneous responses following long wave ultraviolet radiation.

Photo Sensitive Essential Oils

Some essential oils contain up to 2 per cent of furanocoumarins; furanocoumarins are usually found in expressed citrus oils.  Although it is commonly believed that all citrus oils are phototoxic, this is not necessarily the case; for example sweet orange (Citrus sinensis),(as oppose to bitter orange (Citrus aurantium var amara) which is photo sensitive), grapefruit (Citrus paradisi) and mandarin (Citrus reticulata).

Other essential oils which are phototoxic and therefore should be used with care in aromatherapy include:

–Angelica root, seed (Angelica archangelica)
–Caraway (Carum carvi) – low level
–Cassia (Cinnamomum cassia) – low level
–Cumin (Cuminum cyminum)
–Ginger (Zingiber officinale) – low level
–Lemon (Citrus limon)
–Lemon Verbena (Aloysia triphylla) -low level
–Lime (Citrus aurantifolia)
–Lovage (Levisticum officinale)
–Melissa (Melissa officinalis) – low level

Warnings on Using Phototoxic Essential Oils

Use care when using these essential oils to avoid exposure to sunlight, ultraviolet light and sun beds after application; pure bergamot essential oil, when diluted in a carrier oil, is considered to be safely absorbed by the bloodstream two hours after application, although opinions vary as to the exposure period for other essential oils.


Lawless, Julia 1995 The Illustrated Encyclopedia of Essential Oils London: Element
Price, Shirley 2000 Aromatherapy Workbook Thorsons: London, UK
Price, Shirley, Price, Len 1999 Aromatherapy for Health Professionals Edinburgh: Churchill Livingstone

This article was written by Sharon Falsetto and appeared in its original format on Suite101 as Photo Toxic Essential Oils

It is expressively prohibited to copy or use this article in any way unless written permission is given by the author Sharon Falsetto.  If it is discovered that copyright laws have not been complied with, legal action will be pursued by the author Sharon Falsetto.

CopyrightSharonFalsetto2010 All Rights Reserved
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