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- 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
- Tetracyclines, sulfonamides
- Oral contraceptives
- Topicals: psoralens, retinoids coal tars, photoactive dyes (eosin, acridine orange)
- 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).
- Job-related exposure to sunlight
- Light- and fair-colored skin
- 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