Some aromatic extracts are photosensitizing when applied to the skin, followed by exposure to the sun. Photosensitization means that the skin overreacts to sunlight, which can cause redness (erythema).
Some of these extracts demonstrate the same photosensitizing effect when taken orally, even though to a lesser extent (Dugrand & et. Al., 2013, p. 1067).
The common advice given is to avoid topical application of these extracts if you (your client) expect(s) the treated body areas to be exposed to the sun within 24 hours after the application. If you do decide to use them, ask your client to delay exposure to the sun for up to 24 hours after the application.
Photosensitization mainly relates to the presence of furocoumarins (furanocoumarins) in cold-pressed extracts of the peel of fruits of the Citrus genus (not the distilled essential oils) (Dugrand & et. Al., 2013, p. 10683): refer to the extracts in this collection.
The cold-pressed essential oil from the fruit peel of Bergamot (Citrus bergamia, C. aurantium subsp. bergamia) is a famous example. The extract contains (among other things) the furocoumarins bergaptol, bergapten and bergamottine (Dugrand & et. Al., 2015, p. 3). Bergamot extract, containing the controversial molecule bergapten (5-methoxypsoralen), was previously commonly used in sunscreens to help tanning.
Note that Sweet orange extract (Citrus sinensis) and Mandarin extract (Citrus reticulata) contain few coumarins and hardly any photocoumarins (Dugrand & et. Al., 2013, p. 10683) (Dugrand & et. Al., 2015, pp. 9-10).
A number of other extracts is photosensitizing:
- Vanilla absolute (Vanilla planifolia, V. fragrans, fruit) and “Vanilla extract”* (idem) contain vanillin (10.75% in the absolute Lot #ABV100).
- Angelica essential oil (Angelica archangelica, root) contains angelicin, bergapten and psoralen (Tisserand & Young, 2014, p. 194). The IFRA guidelines confirm the risk of phototoxicity and limit the concentration of the oil to 0.8% (cat. 5A) (IFRA, 2020 Amendment 49).
*”Vanilla extract” refers here to a solution obtained by macerating and percolating vanilla pods.
Lot #ABV100: Vanilla absolute by Pranarom.
Photo Bruna Branco @ Unsplash