As pores enlarge enough to accommodate the oil flow, acbe clears up.  And that is most likely the reason why individuals tend to "outgrow" acne.  Just how hormones control oil glands is not yet completely understood, but it is generally thought that sex hormones having male hormone characteristics are the ones that cause oil gland stimulation.  Females also have male hormones; they are produced by the ovaries and the adrenal glands.

Big pores
If you have big pores, it simply means you have big oil glands and the pores have grown to a size necessary to accommodate the oil flow.  If you were to really decrease pore size, you might develop acne!  So if you don't have acne, stop thinking about shrinking pores----your pores are the appropriate size for your oil glands.

Making pores appear smaller
Although pores can't be permanently "shrunk", they can be made to appear smaller by appropriate skin-care measures.

The following are some specific suggestions for skin care that will makes pores appear smaller.  Some of these measures may be too harsh for your skin. Pick those that feel most appropriate to you.
(1) Cleanse the skin well----Use plain bath soap, but not one that is moisturizing, creamy, or superfatted.  Other cleansers labeled "for oily skin" are usually fine, too, as long as they lather and rinse away with water.
(2) Use astringents or fresheners----These products contain alcohol, water, and some other cleansing agents.  The ones specified for oily skin usually contain more alcohol and work best at making pores appear smaller.  Alcohol helps remove water from stratum corneum cells, making them flatter and thereby making pores appear smaller.
(3) Use "scrub' cleansers----Gently scrubbing with these removes the top stratum corneum cells and therefore reduces the thickness of that layer.  That makes pores appear smaller.
(4) Use cleansing pads or brushes----They do the same job as abrasive cleansers and have similar effects on pores.
(5) Use cleansing masks----These products (particularly clay-based ones) reduce the amount of water in the stratum corneum and also remove sone of the top layer of stratum corneum cells.
(6) Do not moisturize----Never moisturize the areas of the face that have large pores.  Moisturizing makes pores appear larger.

But what about skin dryness from all these measures to control pore size? Remember, big pores mean big oil glands and skin that is plenty oily. Drying out the stratum corneum some will not hurt the skin, it just makes pores appear smaller. You may prefer slight surface dryness to the big-pore look. You cannot have it both ways! Continual use of these skin-care measures will give you some control over pore size, but will not completely solve the problem.


Big pores and Dry skin
If you have scaly, dry areas on your face but are confused because you also have big pores, you may have seborrheic dermatitis.  A few individuals have a stratutm corneum that is truly dry (doesn't hold water well) and tends to be flaky, but also have big pores and oily skin.  In this rare case it is better to moisturizer and tolerate the large pores.
# 6 Ways to Clean your Face Better #
(1) Start with clean tools----Wash your hands before washing your face.  No sense in "applying" additional dirt, bacteria, what-have-you to facial skin.
(2) Turn on tepid water----Hot water may feel more relaxing, seem more disinfecting, but it is more drying.
(3) Don't overscrub----You aren't going to get your skin any cleaner and you may end up irritating it.  If you're pink hours after cleansing, you're scrubbing too hard, ease off. If you've got acne-prone skin, you may even cause a flareup.  Spare the elbow grease.  You really don't need to rub your face to remove dirt, makeup, etc.  A gentle massaging action with the pads (the fleshy part) of your fingertips (or a washcloth, sponge, or brush) nudges away what you don't want on skin.  Rule of thumb: The rougher the tool, the lighter your touch should be.
(4) Rinse rapidly----Don't let the cleaser sit on your skin and don't massage forever, you may force dirt, makeup, etc., into skin instead of cleaning it out!
(5) Rinse thoroughly----Probably the most important and most overlooked step of all.  Skin irritation--redness, dryness, stinging, tightness--may result from cleanser residue that wasn't rinse away.  What you should do?  Rinse your face really well, until you think you've removed all traces of cleanser.  Then rinse, rinse, rinse some more.
(6) Rinse clean----Your splashes after cleansing should be with clean water, not water that has been standing in the sink, full of dissolved cleanser and cleanser residue.

Pat dry----Again, vigorous rubbing may feel good, but you should take it easy on facial skin.
# Cleansing Tools #
Brushes, scrubbing pads, natural sea sponges, and washcloths are traditional cleansing tools.  Keep your tools clean! (that goes for fingertips, too.)  Using the same washcloth time after time is not a good idea, it gets warm and wet and becomes a hospitable environment for bacteria.  Change washcloths daily.  Cosmetic brushes should be rinsed thoroughly after each use.  Shake well to remove excess water, and leave them to dry bristle side up.  Brushes do wear out, figure on replacing yours once a year.  Instore test for gentleness: Press bristles on your inner elbow.  If it feels rough there, it'll feel rough on your face.