Updated 15 July 2014

Causes of acne

Acne is caused by the increased production of oil, the obstruction of follicles and their infection and eventual rupture.


What are the causes of acne?

Acne occurs when the sebaceous (oil-secreting) glands in the skin and along hair shafts become clogged and inflamed, and infected by bacteria.

good bacteria vs. bad bacteria

The hair consists of three components:

  1. The hair follicle itself with an emerging hair shaft
  2. The sebaceous (oil) gland which opens into the hair follicle
  3. The sweat (apocrine) gland which opens into the hair follicle  

Four factors are involved in the development of acne:

  1. Increased production of oil stimulated by androgenic (male sex) hormones. During the teens, hormones stimulate hair growth, as well as oil secretion by the sebaceous glands. Hormonal changes can stimulate sebaceous glands to produce more sebum. Therefore, anything that raises hormone levels (for example pregnancy, stress, menstrual periods and certain medicines, such as corticosteroids) can aggravate acne. The male sex hormone testosterone, which is present in both men and women, is mainly responsible, but the female sex hormone progesterone also contributes to acne in women. Some babies are born with acne because their mothers pass certain hormones on to them just before birth. This is rare and usually self-limiting.
    Obstruction of the opening of the follicle caused by increased production of keratin
  2. Infection by a bacterium, namely Propionibacterium acnes. The bacteria Propionibacterium acnes and Staphylococcus epidermis occur naturally in hair follicles. If there are too many bacteria, they may secrete enzymes that break down sebum, promoting inflammation in the follicle. Some people may be more sensitive to this reaction than others, making their acne more severe.
  3. Rupture (Breakage of the follicle leads to inflammation.)

Read: inflammation tied to cancer

Genes and skin type may predispose a person to acne. Genetic factors may play a role.

Stress may aggravate acne, but cannot cause it. Acne, however, may cause stress.

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