We all assumed that once puberty was over the horror of our acne would leave as well, but for millions of adults this is the case and they are left wondering what caused their adult acne. Currently the causes of acne appear to be the result of a combination of factors.
You can have a genetic predisposition to adult acne and hormones do play a part as well. Genetics refer to how easily the acne causing bacterium can spread on your skin and just how your body responds to that bacterium. Typically our skin tissue swells and the more it swells the more unsightly your adult acne can appear. Further swelling is the reason you do not want to squeeze your acne, because it makes it appear worse.
As adults we are still subject to our hormones, although they may not be as raging as they were when we were teenagers. Fluctuations in both estrogen (female hormones) and androgens (male hormones) cause an increase in acne during certain times, such as the week or so before the period.
Cofactors are those promoters of acne. One would assume that eating greasy foods is a cofactor, except that what you eat with the possible exception of vitamins that are good for the skin, does not affect your risk of acne. Real cofactors are Stress, which causes the body to release stress hormones like Cortisol, the environment, various medicines, irritation, and some cosmetics and lotions.
Environmental factors such as pollution and exposure of the skin to grease in the workplace can dirty the skin and clog pores helping to trap the acne bacteria inside. Some medications have been known to affect the body's hormonal levels which can lead to acne. Although you may be tempted the irritation of persistently scrubbing the skin raw to clean your face can worsen acne, just as the rubbing of the bridge of your eyeglasses across the bridge of your nose can lead to acne there. Anything that rubs against the skin will cause irritation; swelling and can help to further press pollutants into the pores. Lastly not all kinds of make up and lotions will clog the pores. You need to read the labeling to see if it's non-comedogenic or non-pore-clogging. Otherwise the materials in say a fine face powder can get into the pores and mix with your skin's oils to create little plugs blocking in bacteria.
Do not feel as if you are the only person struggling with moderate to severe acne, all of these factors can work together to create adult acne and there are many people working to combat it.