Intrinsic skin aging is caused primarily by internal factors within the body, such as genetics and the normal aging processes.

Extrinsic skin aging, or photo-aging, is caused by environmental factors such as sunlight and lifestyle habits such as smoking.

With each passing year, the average moisture content of the stratum corneum decreases gradually as a result of hormonal changes that, over time, cause a reduction in sebum production.

Cigarette smoking profoundly affects skin aging, as nicotine intake expedites the breakdown of skin cells.