What causes adult acne breakouts?

Several factors can play into adult acne breakouts.  Pregnancy, menopause, a poor cleansing routine and overuse of dermatologic prescriptions are just a few.   A poor cleansing routine can cause a skin to become to oily or to dehydrated.  For example, using an exfoliant daily as a cleanser will stimulate the skin to often and cause excess skin to flake back into the pores which will cause them to be clogged and produce excess oil leading to breakouts.  Not exfoliating enough will leave the pores filled with excess dirt and oil which will lead to blackheads and breakouts.  As the skin ages, the natural exfoliating process slows down and the need for exfoliation becomes more important.  The ideal use of exfoliants is 2 to 3 times a week.  I recommend using it in the shower after the skin is cleansed so initial debris will be off the skin and the steam will help the pores open making it easier to clean them thoroughly.  After the shower apply moisturizer to help get moisture on the surface of the skin and into the pores which will keep them soft  and less likely to clog. A quick, simple routine that can be used daily is to cleanse, moisturize, and apply sunscreen in the AM and to cleanse and moisturize in the evening.  Using the routine will ensure that the skin is clean and well protected and early excess aging can be prevented and breakouts will be kept to a minimum.  No matter how oily the skin, keeping it moist helps keep bacteria out of the skin which reduces the risk of infection. Pregnancy, adult hormone changes and menopause are  hormone related which is often the cause of adult acne breakouts.  The information listed at the beginning of this answer is referred to as hygenic acne because over the counter treatments used properly will often solve the problem.  Hormone related acne often requires a doctors care, good diet and exercise habits and using medications in the manner in which they are prescribed.  Pregnancy is the mother of all hormone changes as the entire body will react to the chemical changes taking place.  Skin that has always been normal may become oilier or drier which can lead to breakouts in both small pimples or cystic acne growths which will usually balance out after the pregnancy is over. Adult skin changes which are not often addressed with a general practicioner can cause unwanted acne that again with proper care can be fixed.  As the skin ages not only does natural exfoliation slow down, but unwanted hair starts to grow on the face and the back which can clog pores or be so fine that it causes ingrown hairs that will swell and leave welt-like marks on the skin.  Women will usually see the effects of this more than men because of the hormonal make up of a woman's body.  These changes usually start to occur in the late 20's and by the start of menopause have full effects because of the loss of estrogen and increase of testosterone a woman will experience.  The hairs that grow can be coarse, but the fine blond hairs that grow callled Vellus Hairs are the cause of the acne breakouts most common with this condition.  Removal of facial hair with waxing or laser can be helpful but there are now prescriptions available that can slow the growth of hair which will help the chances of the clogging that occurs with growth. Proper use of prescriptions are important because any pill or cream that is prescribed and not available over the counter will work with the skin's chemistry to make the changes necessary to correct acne conditions.  Overuse or lack of use will often make the problem worse and can lead to additional problems that can be avoided.