Acne is a chronic skin condition characterised by the development of spots.

• The size, shape, colour and whether contains pus; are used to classify the spots
• Acne commonly develops on the¹:
  1. Face –  affecting almost everyone
  2. Back – affecting >50%
  3. Chest – affecting  about 15%

Cause

• Sebaceous glands at the base of the hair follicle glands produce too much sebum forming a plug in the follicle.
• If skin on plug breaks, bacteria on the skin contaminates and infects the follicles, causing spots to develop.

Six types of spots develop in acne:

1. Papules: Surface of the skin is unbroken , may appear red or be sensitive and painful.
2. Whiteheads (closed comedones): Small pores blocked with sebum. Pore closes over so no oxidisation occurs. 
3. Blackheads (open comedones): Large pores blocked with sebum. As pores open content oxidises and turns black.
4. Pustules: Inflamed and generally pus-filled. May appear white or yellow.
5. Nodules: A severe form of lesion that develop under the skin and generally contains pus but hard to the touch.
6. Cysts: A severe form of lesion inflamed and filled with pus. Often painful requiring medical treatment.
    

Treatment for moderate to severe acne

• Azelaic acid – Removes dead skin and kills bacteria on the skin.
• Topical antibiotics -  Kills bacteria on skin that may infect the hair follicles. 
• Topical Retinoids  - Exfoliates the skin to prevent build up in the hair follicles.
• Isotretinoin tablets – Only recommended for severe cases as a wide range of side effects.

^{1. https://www.nhs.uk/conditions/acne}