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Clinical Features:

  • Chronic inflammatory disease of pilosebaceous units
  • Characterised by formation of comedomes, papules, pustules, nodules and cysts.
    • comedomal
    • papules
    • pustular
  • Face 99%, back 60-%, chest 15%
  • Most adolescents develop mild comedomal acne

Factors Involved in developing acne

  • High GI Diet
  • Premenstrual flare
  • Stress- anecdotally HSC
  • Occupation to oil hydrocarbons- e.g the fryer at McDonalds
  • UV Exposure
  • Most cosmetics are no longer comedomal.
  • Do’t squeeze it- increases severity and risk of scarring


  • Increased sebum production (active sebaceous glands, stimulation by androgens at puberty, PCOS in females)
  • Ductal hypercornification ( the ductal keratinocytes at the opening of the sebaceous glands proliferating, blocking the gland – resulting in blackheads)
  • Ductal colonisation with propionibacterium acnes ( is not infectious, cause inflammation, there number relates to severity of acne, produces inflammatory mediators which diffuse into the dermis
  • Inflammation (can cause scarring- the deeper the process the higher the risk of scarring).


  • Comedomal and microcomedomal
  • Mild inflammatory
  • Moderate Inflammatory ( can feel it getting deeper- deep seated papules and pustules)
  • Nodulocystic acne ( deep, painful, takes 4 – 6/52 to settle, scarring if not treated)



  • History ( how long has it been active, any triggers identified, is there a family history of acne and acne scarring, treatment given to family members, how do you feel about it)
  • Examination: assess face, chest, back- grade the predominant acne at each site, palpate skin to assess induration, assess signs of hyperandrogenisation, signs of scarring or potential for scarring


  • For Hormonal Acne: free testosterone, SHBG, FAI, LH, FSH, DHEAS,   bsl, prolactin

Differential Diagnosis:

  • Rosacea
  • Perioral dermatitis- trigerred often by a steroid or other creams
  • Acneiform drug eruption
  • Folliculitis on the trunk
    • Bacterial or pityrosporum- bx and ask them to look for putyrosporum if pityrosporum- a yeast very itchy- clothing that doesn’t breathe, application of greasy sunscreens, an oily skin tendency, stress or fatigue, diabetes, OCP: topical therapy is not always effective- but worth a try- pts may also have tinea versicolor or seborrheic dermatitis- nizoral shampoo or Selsun Shampoo or oral nizoral or sporonox.



  • Comedomal
    • Usually treated with topical therapies
    • Keratolytic (thin the thickened skin on top of the acne e.g salicylic acid- good in seborrheic dermatitis cradle cap, acne)and comedolytic agents ( benzoyl peroxide, tretinion, adapalene
    • Retinoids the topical treatment of choice in both comedomal and mild inflammatory, avoid in pregnancy ADEC D –Adapalene: ( differin) combo product with benzoyl peroxide is (epiduo), isotetinoin (isotrex)
    • Benzoyl Peroxide (use 2.5% or 5% no benefit in using 10% just dries skin out more Brevoxyl, Benzac, Clearasil) continue for six weeks before assessing efficacy
    • Azaleic Acid ( inhibits growth of propionibacterium acnes and reduces follicular keratinisation)acne, rosacea, melasma
  • Mild Inflammatory Acne
    • Use a combo needs an exfoliating ( comedolytic agent), and an antibiotic.
    • g clindamycin with benzoyl peroxide ( Duac once daily)
    • Adapalene and benzoyl peroxide ( Epiduo Gel – now PBS listed)


  • Moderate Inflammatory acne
    • Clindamycin, benzoyl peroxide plus a topical retinoid
    • Anti androgen in a female, topical BP, retinoid antimicrobial


  • Severe Cystic Acne
    • Needs oral isotetinoin to achieve remission
    • Maintenance with a topical retinoid.
    • Minor flares after isotretinoin use combo antimicrobial, retinoid, BP


  • Which Antibiotic:
    • Doxycycline 50 – 100mg /day: start at 100mg/day as a private script
    • Minocycline- probably bettern doxy but do LFT’s
    • Co-trimoxazole as second line therapy
    • Erythromycin is problematic- GI S/E and increasing resistance
    • 50% of pts are colonised by erythro/ clinda resistant p.acnes
    • Don’t use topical and systemic antibiotics in combination
    • Aim to use oral antibiotics for 8-12 weeks- have breaks every 12/52 to help avoid resistance
    • Minocycline- teeth staining in kids
    • Photosensitivity on doxycycline