Oily skin can occur at any age, often causing breakouts, shiny complexion, enlarged pores, and other effects. While certain hormones released during puberty can cause increased oil production during our teenage years, there may be other reasons why your skin appears oily later in life.Pollutants, environmental irritants, genetics, and heavy makeups or cosmetics are common culprits for excessive oil production, but it can also be caused by over-washing and not using enough moisturizer. When using harsh cleansers, you strip your skin of its natural oils, causing your body to react by producing even more.