Facial Rash

Differential Diagnosis

Common Diagnoses

Occasional Diagnoses

  • Chloasma
  • Sycosis Barbae
  • Drug Side Effect: Especially Phototoxicity
  • Infection (e.g. Herpes Zoster and Simplex, Cellulitis, Chickenpox, Slapped Cheek)
  • Allergic Eczema
  • Acne Excoriée
  • Post Inflammatory Hypo- or Hyperpigmentation
  • Pityriasis Alba
  • Petechiae from Coughing/Vomiting/Straining
  • Other Generalised Skin Diseases (e.g. Psoriasis, Vitiligo)

Rare Diagnoses

  • Stevens–Johnson Syndrome
  • SLE
  • Mitral Flush
  • Tuberous Sclerosis
  • Lupus Vulgaris
  • Sarcoidosis
  • Dermatomyositis

Ready Reckoner

Key distinguishing features of the most common diagnoses

AcneRosaceaSeborrhoeic Eczema ImpetigoPerioral Dermatitis
Mainly Around Mouth PossibleNoNo PossibleYes
Rash Elsewhere PossibleNo Possible PossibleNo
Age >40NoYes Possible Possible Possible
Papules and PustulesYesYesNo PossibleYes
Rapid Response to AntibioticsNoYesNoYesYes

Possible Investigations


Possible:FBC, ESR/CRP, autoantibody screen, CPK.

Small Print:Viral or bacterial swabs, skin biopsy, muscle biopsy.

  • FBC: WCC raised in any infection; may be normochromic, normocytic anaemia in SLE.
  • ESR/CRP, autoantibody screen: ESR/CRP likely to be raised in infection and SLE; autoantibodies may be positive in the latter.
  • CPK: Elevated in dermatomyositis.
  • Viral or bacterial swabs: To help diagnosis in obscure cases or if secondary infection suspected.
  • Skin biopsy; muscle biopsy: The former for suspected lupus vulgaris or sarcoidosis; the latter to confirm dermatomyositis.

Top Tips

  • Do not underestimate the possible impact of a facial rash on a patient’s life. The cosmetic effect may be devastating.
  • A therapeutic trial of antibiotics in acne may take up to 3 months to take effect – ensure the patient is aware of this.
  • Remember that impetigo may simply represent superinfection of an underlying skin problem, such as eczema, which will require treatment in its own right.
  • Check on OTC medication usage. In particular, remember that hydrocortisone 1% cream is available over the counter – inappropriate use might aggravate rosacea and perioral dermatitis.
  • Parents are sensitised to non blanching rashes. They can be reassured that such a rash restricted to the face (indeed, restricted to the entire distribution of the superior vena cava) is not due to meningitis.

Red Flags

  • A complaint of dramatic facial ‘sunburn’ in the elderly may well represent a phototoxic reaction – check the drug history.
  • Beware the acute onset of unilateral unexplained facial erythema with mild oedema, especially in an elderly patient. This may well be the start of cellulitis or herpes zoster.
  • Warn patients with facial zoster or herpes simplex infection near the eye to report any ocular problems.
  • Acne excoriée may be a marker of significant psychiatric pathology.
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