Acne in adults female or male is also called post a dolestcent acne. It can be persistent, with onset during teenaged years, or late onset beginning after age of 25 years. But, it affects up to 15 % of women, and is usually reported to be less common in men. According to self.com, For the last 10-20 years, adult acne has been increasing. It can even go into your 50s, right menopause. And If you had acne as a teen, chances are you've got oily skin that's prone to breakouts. But even if you didn't, it's still possible you'll end up with adult acne.

Image credit: www.aad.org

Adult acne causes

If you're getting acne as an adult, it is likely due to one or more of the following reasons:

1. Fluctuating your hormone levels
   The fluctuating in hormones, such as before one's menstrual cycle, is the main cause (Julia Tzu,MD), during pregnancy, after discontinuing birth control pills.
2. Stress can be an extra driving force.
   Researchers have found a relationship between stress and acne flare-ups. In respons to stress, our bodies produce more androgens. These hormones stimulate the oil glands and hair follicles in the skin, which can lead to acne.
3. Family history
4. Using wrong products
   If you have oily or combination skin and are prone to breakouts, you should be using skincare products labelled "oil-free", non-comedogenic", "water based" (Schultz says). If you want to make sure your cleanser, sunscreen, moisturizer, and all other products contain one of these terms. These products are least likely causing acne.
5. Medications side effect
6. Undiagnosed medical condition
   Sometimes, acne is a sign of an underlying medical condition. Once medical condition is diagnosed and treated, the acne often clears.
7. Specific foods
   We've heard foods that allegedly cause acne include chocolate, fried foods, pizza, caffeine, nuts.
8. Adult acne caused by cleansing too frequently and intensely.
9. Sweet tooth is causing a skin problem.
10. Pollution isn't helping your case either.
    Air pollution just puts this layer of crap on your face, Schultz says. 

According to  researcher, more than 80% of cases adult acne occur in women. It's thought many cases of adult acne are caused by the changes in hormone levels that many women have at certain time.


References:

• http://www.dermnetnz.org/topics/adult-acne/
• http://www.self.com/story/adult-acne-causes-and-treatments
• https://www.aad.org/public/diseases/acne-and-rosacea/adult-acne
• http://www.nhs.uk/Conditions/Acne/Pages/Causes.aspx