The skin pores can become enlarged due to sebum (oil) packed deep inside them, making the pore shafts widen. Exfoliate three times a week to remove the sebum, use a pore-minimizing gel over the area with open pores.
It can also be helpful to sweep the entire face every morning with a salicylic acid or glycolic acid toner, both act as exfoliators and help to dissolve dirt and oil deep inside the pores.
Treat just the area with the largest pores two or three times a week with a product that contains sulfur, so that the healthy skin won’t get too dried out. Dab it on and leave on 5 to 10 minutes. Then rinse with warm water.