While there is no one authoritative answer on the causes of adult acne, there are some things that are known for sure:

Every hair on our bodies is anchored in a hair follicle and each hair follicle has a sebaceous gland attached to it.

Each one of these sebaceous glands produces an oily substance known as sebum. The sebum protects your skin and makes your hair shiny.

Some people's bodies produce lots of sebum -- this results in oily skin.

The oilier your skin is, the better chance you have of getting blackheads, whiteheads or pimples, and acne. This happens because hair follicles occasionally become plugged up with the sebum and with dead skin cells. In fact, every minute of the day, though you can't see it happening, skin creates about 30,000 new skin cells. In addition, skin shed about 30,000 of the old, dead skin cells. There are always lots of dead skin cells to contribute to the process.

Since everyone of every age has hair follicles, sebaceous glands and dead skin cells everyone of every age can, at least theoretically, get acne.

There are some things, however, that are known to contribute to acne in adults of all ages:

Medication. There are some medications that are known to, at least in some people, cause acne. Acne is one of the principal side effects of the 'anti-aging' drug known as DHEA. Some other drugs that have acne as a undesired effect are: anabolic steroids, some anti-epileptic medications, the anti-tuberculosis drugs isoniazid and rifampin and also lithium and iodine-containing medications.

Chafing. A form of acne known as 'acne mechanica' can arise from a repeated pressure on a particular area of your body. For example, wearing a heavy back pack every day, wearing a safety helmet or a tight cap or playing an instrument such as a violin or cello will all put a repeated pressure on some area of your body and that area may develop an outbreak of acne.

Chemical exposure. An overexposure to certain chemicals can cause an acne condition known as chloracne to appear as an outbreak of blackheads, cysts, and pustules, most commonly on the cheeks, behind the ears, in the armpits and in the groin region. The chemicals known to cause this are forms of chlorinated dioxins (such as those used to produce herbicides) and dibenzofurans.

Metabolic conditions. We know that adolescent acne is caused by hormonal imbalances during puberty and have found that hormonal imbalances at any age will create the same condition -- hormone imbalances such as those brought about by pregnancy and menstruation or hormonal abnormalities for any reason, such as an adverse effect of a medication, can induce acne.

Treatment: If you suspect you have adult acne you should make an appointment to see your doctor or get a referral to a dermatologist, if only to determine that it really is acne and not some skin condition that only resembles acne.

Aside from following your doctor's advise and using whatever medication your doctor recommends by following the directions for its use, there is one other thing you can do to help cure acne. Be careful and gentle with your skin. Irritation of the skin can make acne worse and should be avoided. Don't pick at acne or scratch at it with your fingernails (or anything else). When bathing, don not use a rough or abrasive wash cloth or a stiff brush. These things will irritate your skin and cause even more damage to your hair follicles.