Large pores

 
The appearance of large pores is usually caused by overactive
sebaceous (oil) glands. This causes the pores to expand to
accommodate the excess sebum production. When pores
become clogged with cellular debris causing blackheads,
they can appear even larger. 
 
Although there is nothing you can do to “shrink” pores,
topical niacinamide can help to inhibit oil flow, decreasing
their appearance. Alpha + beta hydroxy acids and Vitamin A
analogues (such as retinol and retinaldehyde) help minimise
large pores by keeping them clear of debris.
 
MYTH BUSTER
Toners are traditionally associated with shrinking pores,
but there is nothing scientifically proven to reduce the size
of a pore. The tight feeling that toners cause is actually
related to the depletion of the skin’s essential oils by
astringent ingredients such as alcohol.