Feature Article

Common causes and management of photosensitivity

Lee Mei Yap, Peter Foley, Christopher Baker



A high index of suspicion is needed to diagnose cases of photosensitivity as the temporal relationship of a rash on exposed sites with sunlight exposure is not always obvious.

Key Points

  • Photosensitivity is a feature of a wide range of disorders, including the idiopathic photodermatoses, some metabolic disorders and a few rare genetic syndromes. It also occurs after exposure to certain drugs and other exogenous agents.
  • A photosensitive reaction classically occurs on sun-exposed sites and spares those that are shaded or covered by clothing.
  • A history of exposure to a photosensitising agent must be explored in all patients with photosensitivity.
  • Referral to a dermatologist, or a photodermatology centre if available, for light testing and patch testing may be helpful in establishing the diagnosis.
  • General treatment measures include avoidance of photosensitisers and sun protection.
  • Specific treatment measures include oral corticosteroids, antihistamines, antimalarials, cyclosporin, azathioprine, thalidomide and light therapy.