There are three main causes for large pores: Oily Skin, Age and Gender
Our bodies produce sebum, an oily substance we secrete to make the skin waterproof and to keep it from drying out. People who have naturally oily skin tend to have larger pores. This happens because when oil and dirt collect in your skin, your skin swells and your pores look larger than they normally would.
Another contributing factor is age. As you get older your skin loses its elasticity, which can cause your pores to look bigger. Sun damage, which typically accumulates with age — the older you are, the more you’ve been exposed to the sun — also affects the appearance of pores. It makes your skin thicken, causing skin cells to collect around the edges of your pores, which stretch them out.
In general, males tend to have larger pores than females. Women might experience enlarged pores more often during hormonal changes, however, particularly during menstruation.
Genetic predisposition may also be a contributing factor when it comes to pore size. If one or both of your parents have large pores, you might also have or eventually experience a similar condition.