Grapefruit oil has photosensitive effects if oxidized, contributing to its phototoxic, photo-carcinogenic, sensitizing properties. The possible skin issues of using Grapefruit oil are hyperpigmentation, allergic reactions, irritation, sunburns, blisters and rashes. These reactions mainly occur when the skin is exposed to visible sunlight within 12 hours of use.
The underlying reason is the reaction of the photoactive chemical constituents in Grapefruit oil that attracts light and leads to toxicity through molecular changes in the skin surface. Certain studies state that Grapefruit oil promotes the formation of tumors on the skin of mouse, by the key carcinogen, 10-dimethyl-l, 2-benzanthracene.
The primary chemical component responsible for the phototoxic and adverse skin effects of Grapefruit oil is Limonene, which accounts to about 90% of this oil along with few other furanocoumarins ( the non-volatile compounds like bergapten, bergamottin and epoxy-bergamottin.)
The safe dilution level of Grapefruit oil by the International Fragrance Association (IFRA) is 4%, which is about 24 drops per ounce of any mild carrier oils. This is particularly to prevent phototoxicity in products used for dermal applications except for bath products like soaps, shampoos and other wash-off preparations.
According to the European decree, essential oils that contain furanocoumarins must be used preferably when the level of bergapten does not exceed 15 ppm (parts per million) in finished cosmetic products intended for use on parts of the skin that are in contact with sunlight (other than rinse-away products) and 1 ppm in bronzing and sun protection products.
Grapefruit oil should be used only for topical application, preferably blended with mild carrier oils (good for use after a patch test on your skin). Never use essential oils for ingestion, as internal use of essential oils might pose adverse health effects. Undiluted Grapefruit oil can cause skin irritation and this oil is claimed to be toxic to cats.
A 2005 study published that “the scent of Grapefruit oil and its active constituent, limonene affects the autonomic neurotransmission and blood pressure through central histaminergic nerves and the suprachiasmatic nucleus.”
Studies state that ingesting furocoumarins may also cause phytophotodermatitis. It is better to avoid Grapefruit oil if you are pregnant or breastfeeding as the safety of this oil during carrying or nursing are not established.
In a much similar way like Bitter orange oil, Grapefruit oil is said to restrain important enzymes in the intestines and liver, leading to have an impact on the blood levels at the time of taking medicines that are antidepressant, antiviral, anti-anxiety, calcium channel blockers, steroids, anti-malarial, immune modulators, prokinetics, statins and on par with caffeine intake. The presence of furocoumarins has led to the term ‘Grapefruit effect’, which signifies the interaction between furocoumarins and enzymes that are engaged in drug metabolism, specifically cytochrome P450.
Use Grapefruit oil only after medical advice, if you are taking any other prescription medicines. Startlingly, furocoumarins are also used in different remedies along with long-wave ultraviolet light therapy for treatng psoriasis, mycosis fungoides and vitiligo.
The traditional remedial values of this oil are antidepressant, antiseptic, anti-tumoral, antioxidant, lymphatic, stimulant, tonic, diuretic, disinfectant, aperitif and fat dissolving.