What is Phototoxicity? It is a toxic response when skin is exposed to particular chemicals and subsequent exposure to light. Photosensitivity is having an increase in the racitivity of the skin to sunlight. This can occur when particular essential oils applied to the skin (this does not include shampoos, soap, bath preparation, or anything that is washed off the body) react when exposed to UVA light. The skin can become inflamed, blister and burn (reddening). Most citrus oils are considered to be photo-toxic, but not all are. It all depends on the method of extraction for some oils. Click on the images below to view a larger image and read about the suggested product usage for some of the oils.