Photo-aging is a technical term for the premature aging of the skin, caused by frequent unprotected exposure to sunlight. In the short term, damages include the usual sunburn, while long term damages includes unattractive skin changes as well as pre-cancer and cancer changes. The features of photo-damaged skin usually take the form of wrinkles, others include:

• Inelasticity and appearance of a thick leather
• Saggy and loose skin
• Dryness and roughness
• Uneven pigmentations
• Pigmented spots such as freckles
• Sallowness (yellowish discoloration)

Some recent studies have revealed various biochemical processes in the skin, whose end products are found to be responsible for photo-aging. One of these is Advanced Glycosylation End products (AGEs). These are formed by attachment of glucose and ascorbic acid to the long-lived proteins, such as collagen and elastin. AGES then cross link more proteins in the dermis irreversibly. Another is the singlet oxygen radicals ( free radicals ) which directly and indirectly cause damage to the inside structures of many cells.