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To understand better the causes of acne, it is useful to learn more about the sebaceous glands, which play a key role in the condition's development.

Sebaceous glands

Sebaceous glands are tiny glands found near the surface of your skin. The glands are attached to hair follicles. A hair follicle is a small hole in your skin that an individual hair grows out of.

The purpose of sebaceous glands is to lubricate the hair and the skin in order to stop it drying out. The glands do this by producing an oily substance called sebum. In acne, the glands begin to produce too much sebum. The excess sebum mixes with dead skin cells and both substances form a plug in the follicle.

If the plugged follicle is close to the surface of the skin, it will bulge outwards, creating a whitehead. Alternatively, the plugged follicle can be open to the skin, creating a blackhead.

Normally harmless bacteria that live on the skin can then contaminate and infect the plugged follicles, resulting in papules, pustules, nodules, and cysts. See types of spots.

The triggers of acne


Cases of teenage acne are thought to be triggered by increased levels of a hormone called testosterone that occurs during puberty. The hormone plays an important role in stimulating the growth and the development of the penis and testicles in boys, and maintaining muscle and bone strength in girls.

The sebaceous glands are particularly sensitive to hormones, so it is thought that the increased testosterone causes the glands to produce much more sebum than the skin actually needs.


In cases of adult acne, over 80% of cases occur in women. It is thought that many cases of adult acne are a result of the changes in hormone levels that many women will experience at certain points during their life. Possible triggers for adult acne include:

  • Periods: some women experience a flare-up of acne just before their period is due.
  • Pregnancy: many women experience symptoms of acne during pregnancy, usually during the first trimester (first three months).
  • Polycystic ovary syndrome: this poorly understood, but common condition can cause acne, weight gain and the formation of small cysts inside the ovary.
  • Side effects of medication: in some people, certain types of medication can cause acne, e.g. steroid medication and lithium (which is often used to treat depression and bipolar disorder).
view information about Acne on www.nhs.co.uk »

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