• Light-induced eruptions seen in a pattern of photodistribution
    • Phototoxic reactions: result of an acute toxic effect on skin of ultraviolet (UV) light alone (sunburn) or together with a photosensitizing substance (nonallergic) (1)
    • Photoallergic eruptions: a form of allergic dermatitis resulting from combined effects of a photosensitizing substance (drugs or chemical) plus UV light (immunologic/delayed hypersensitivity)
    • Polymorphous light eruption (PLE): chronic, intermittent, light-induced eruption with erythematous papules, urticaria, or vesicles on areas exposed to sunlight
  • System(s) affected: skin/exocrine
  • Synonym(s): sun poisoning; sun allergy



  • PLE usually occurs after the first intense exposure to the sun in the spring or summer.
  • Predominant age: all ages
  • Predominant sex: male = female

May be as high as 20% in some areas

Etiology and Pathophysiology

  • Sunlight
  • Phenothiazines
  • Diuretics
  • Tetracyclines, sulfonamides
  • Oral contraceptives
  • Topicals: psoralens, retinoids coal tars, photoactive dyes (eosin, acridine orange)
  • 5-Fluorouracil
  • Quinine
  • Sunscreens containing para-aminobenzoic acid (PABA)
  • In the United States, ~115 chemical agents used topically are known to cause photodermatitis.

Predisposition occurs in inbred populations (e.g., Pima Indians).

Risk Factors

  • Job-related exposure to sunlight
  • Light- and fair-colored skin

General Prevention

  • Sunlight avoidance/protective clothing
  • Identification and avoidance of causative drugs (see “Etiology and Pathophysiology”)
  • Sunscreens: Apply before exposure:
    • Zinc oxide: opaque, cosmetically less acceptable; some preparations are available that when applied dry clear
    • Chemical: Use sun protective factor (SPF) >30 for maximum protection; substantively resistant to sweat and swimming; cosmetically more acceptable (2)
  • Avoid direct sun exposure.
  • Use appropriate clothing and hats to avoid sunlight exposure (3).

Commonly Associated Conditions

  • Sunlight aggravation of systemic lupus erythematosus (SLE)
  • Persistent light reactivity
  • Actinic reticuloid

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