The causes for adult acne are often the same as they were during the teen years for people who had acne as teenagers. However, for adults who never had acne before, there can be new reasons for why they have now developed acne.

While the exact causes of adult acne are debatable, it is well known that hormonal fluctuations can trigger the onset of adult acne. That is why many women suffering from adult acne notice a change in their acne around the time of their menstrual cycle.

While hormones are a big contributor to the onset of adult acne, there are a number of other reasons as well. Here are eight major causes of adult acne.

1. The Poorly Understood Cause of Most Teenage and Adult Acne

Most dermatologists focus entirely on the skin when they talk about the causes of teenage and adult acne. They concentrate on how dry cells mix with sebum, and the resulting blockages or plugs that occur in the pores. These plugs then lead to sebum build-up, and bacterial infections often result.

Although there is certainly truth to this answer, it is not complete. And failing to understand the deeper causes of teenage and adult acne unfortunately results in most acne treatments failing.

The cause of acne is actually toxins and wastes that build up inside the body that cannot be properly eliminated. The body has several "normal" methods for expelling these toxins, through the liver, kidneys, colon, small intestine, and other organs.

However, if any of these organs are weak and can't handle the load -- or if the buildup is too great or too rapid -- acne can result.

That is because the body absolutely must get rid of the toxins. So in a last ditch effort to cleanse itself, the body tries to flush the unwanted toxins out through the pores of the skin. The sores and blemishes that result are what we call acne.

Now let's discuss additional causes of adult acne.

2. Adult Acne and Menstruation

Oftentimes, a woman's adult acne will revolve around her menstrual cycle and pimples will develop a few days before the onset of her period.

The reason for this is that during this time, a woman's estrogen levels are decreasing while her progesterone levels begin to rise. This causes the sebaceous glands to produce more oil, which can result in the onset of pimples.

3. Adult Acne and Pregnancy

As if pregnant women don't have enough to worry about, they often have to worry about developing acne too!

It is very common for adult acne to present itself during pregnancy. Women undergo a slew of hormonal changes during pregnancy.

Acne is often at its worst during the first three months of pregnancy, when hormones are fluctuating all over the map. However, it is possible for acne to last throughout the entire pregnancy and to continue into the breastfeeding period.

Fortunately, most pregnant women will likely go back to their pre-pregnancy complexions with time.

4. Adult Acne and Polycystic Ovarian Syndrome

Polycystic Ovarian Syndrome, also often referred to as Polycystic Ovarian Disease, is one of the most commonly misdiagnosed conditions in women. The condition affects six to ten percent of all women -- and most women don't even know they have it!

While irregular or absent menstruation is the most common sign of Polycystic Ovarian Syndrome, acne is almost always present when this condition occurs.

Women suffering from Polycystic Ovarian Syndrome suffer from substantial hormone imbalances. When these hormone imbalances are treated, the acne often resolves itself.

5. Adult Acne and Menopause

It would be nice to think that menopause would signal the beginning of the end of adult acne. Unfortunately, adult acne can appear in postmenopausal women, too.

While it's not common, it's not impossible to experience the onset of acne during your 40's, 50's and beyond. When acne develops at this stage in the game, it's usually mild, but it can still be a cause of embarrassment and annoyance.

6. Adult Acne and Medication

Research has shown that some medications can cause adult acne. These include anabolic steroids, some meds that contain lithium and iodine, isoniazid and rifampin, and some anti-epileptic medications.

7. Adult Acne and Chemicals

Chlorinated industrial chemicals can create a skin disorder called chloracne, which is actually a type of rash that is caused by exposure to chlorinated industrial chemicals or herbicides.

8. Adult Acne and Physical Pressure or Friction

Finally, adult acne can be caused by certain types of chronic physical pressure to the skin, such as the placement of a violin beneath the jaw and chin, or the chafing from the straps of a backpack. This type of acne is called acne mechanica.