An overproduction of sebum can be triggered by factors like hormonal imbalance, high level of stress, certain allergens, and a poor diet that contains a high amount of harmful fats. When the skin pores get clogged, the oil cannot leave the skin through the pores. Such clogged skin pores can trap dirt and bacteria present on the skin. This can eventually cause infections, inflammation, and redness, or the development of acne.