When ultraviolet (UV) radiation, a form of radiation which makes up approximately 10% of sunlight, comes in contact with particular substances it can initiate a series of chemical and biological reactions. The resulting immune system reaction is known as photosensitisation.
Some essential oils contain furocoumarins (organic chemical compounds) that make some people’s skin more sensitive to the effects of UV radiation. When photosensitive skin is exposed to UV radiation, it may cause the formation of free radicals, inflicting damage to cellular membranes, proteins, and organelles. Acutely, this may result in temporary darkening of skin pigment and irritation, much like a sunburn. More extreme exposure may cause burns or hives.
