Understanding the active ingredients in sunscreen is a bit like learning a foreign language that uses a different alphabet. Suffice it to say in short that sunscreens are made up of a combination of two types of ingredients: those that reflect ultraviolet (UV) rays and those that absorb UV rays. Although that might sound simple enough, there are also two types of rays: UVA rays and UVB rays. UVB causes sunburn at the outer layers of skin, but UVA causes sun damage that reach deeper layers of skin. Both UVA and UVB radiation can contribute to the development of skin cancer. Octisalate (octyl salicylate) is an organic compound (colorless liquid with an oily consistency and a slight floral fragrance) that is used to absorb UVB rays and also add water-resistant properties to the formula. It is not a particularly strong absorbent, so it usually appears along with other ingredients. Octisalate degrades when exposed to sunlight, which means it needs to be reapplied frequently. The FDA has determined that the levels used in cosmetic and beauty products would not cause any adverse reaction and has approved octisalate for use in sunscreen with up to 5% concentration . Keep in mind that a sunscreen’s Sun Protection Factor (SPF) is a gauge of how well the formula protects the skin from UVB rays. It does not gauge protection from UVA rays.