What Are the Causes of Acne?
No one really knows why some people get acne and others don’t. It does seem to be at least partly hereditary. But many times, children of people who had severe acne don’t have any at all. The opposite can also be true – children can have severe acne when their parents had flawless skin.

There are several internal factors, however, that are known to be linked to acne:

• Hormonal changes or activity – During puberty, an increase in male sex hormones called androgens cause the follicular glands to get larger and make more sebum. The sebum often plugs up the glands and causes pus to form. The onset of puberty is often the precursor for acne, but females are prone to acne eruptions at the beginning of each menstrual cycle, or when ovulating.
• Besides the sex hormones, several other hormones have been linked to acne: the androgens testosterone, dihydrotestosterone (DHT) and dehydroepiandrosterone sulfate (DHEAS), as well as insulin-like growth factor 1 (IGF-I). In addition, acne-prone skin has been shown to be insulin resistant and contribute to acne formation.
• Family/Genetic history. The tendency to develop acne runs in families. For example, school-age boys with acne often have other members in their family with acne as well. Studies show that a family history of acne is associated with an earlier occurrence of acne and an increased number of retentional acne lesions.
• Inflammation, skin irritation or scratching of any sort will activate inflammation. This is why some anti-inflammatories are known to improve acne.
• Stress, through increased output of hormones from the adrenal (stress) glands. While the connection between acne and stress has been debated, scientific research indicates that “increased acne severity” is “significantly associated with increased stress levels.” The National Institutes of Health (USA) list stress as a factor that “can cause an acne flare.” A study of adolescents in Singapore “observed a statistically significant positive correlation […] between stress levels and severity of acne.”
• Hyperactive sebaceous glands, secondary to the three hormone sources above.
• Accumulation of dead skin cells that block or cover pores.
• Bacteria in the pores. Propionibacterium acnes (P. acnes) is the anaerobic bacterium that causes acne. In-vitro resistance of P. acnes to commonly used antibiotics has been increasing. This condition is really a combination of the over-production of sebum in the hair follicles and the growth of bacteria. As the pores and hair follicles become blocked, bacteria begins to feed on on the sebum. This leads to inflammation and infection around the hair follicle and the formation of pimples of puss-filled blackheads.

But that’s not all that causes acne. Stay tuned for Part 2 of “What Causes Acne?” Aside from internal factors, there are additional external factors that we will be discussing in Part 2.