Acne is a skin condition that develops when glands in the skin's pores produce too much oil, causing the pores to become blocked. When this happens, pimples or cysts develop because oil, dirt, bacteria, and dead skin cells build up in the pores.

Acne usually appears on the face and shoulders but can develop on other parts of the body as well. It can have several different appearances, including:

  • Pimples (whiteheads or blackheads)
  • Crusting of skin bumps
  • Cysts (hard painful bumps in the skin)
  • Small red bumps
  • Redness and swelling around pimples or cysts
  • Scarring of the skin

Many things can cause the skin’s pores to become clogged with too much oil. Hormonal changes are one of the most common causes of pimples. These changes can happen during puberty, menstrual periods, pregnancy, menopause, and periods of stress. Other factors that can lead to acne are greasy or oily cosmetics and hair products, certain drugs (steroids, testosterone, estrogen, birth control pills, and phenytoin), high humidity, and sweating. Although research does not show that certain foods (such as chocolate, nuts, and greasy foods) cause acne, eating too much food with refined sugars may contribute to it.