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For further information, see CMDT Part 6-52: Photodermatitis

Key Features

Essentials of Diagnosis

  • Painful or pruritic erythema, edema, or vesiculation on sun-exposed surfaces: the face, neck, hands, and "V" of the chest

  • Inner upper eyelids spared, as is the area under the chin

General Considerations

  • Composed of four groups:

    • Primary, idiopathic immunologically mediated photodermatoses

    • Drug- or chemical-induced photodermatoses

    • Dermatoses that are worsened or aggravated by UV exposure

    • Genetic diseases with mutations predisposing to photodermatitis

  • Primary photodermatoses include polymorphic light eruption, chronic actinic dermatitis, and actinic prurigo

  • Drug- or chemical-induced photodermatitis may be either exogenous (manifests as phototoxicity or photoallergy) or endogenous (eg, porphyria cutanea tarda, pellagra) in origin

  • Contact photosensitivity may occur with plants, perfumes, and sunscreens

  • Dermatoses that are worsened or aggravated by UV exposure include systemic lupus erythematosus and dermatomyositis

  • Three percent of persons with atopic dermatitis, especially middle-aged women, are photosensitive

Clinical Findings

Symptoms and Signs

  • Acute inflammatory phase of phototoxicity, which, if severe enough, is accompanied by

    • Pain

    • Fever

    • Gastrointestinal symptoms

    • Malaise

    • Prostration

  • Erythema, edema, and possibly vesiculation and oozing on exposed surfaces

  • Peeling of the epidermis and pigmentary changes often result

  • The lower lip may be affected

Differential Diagnosis

  • Contact dermatitis

  • Porphyria cutanea tarda

  • Systemic lupus erythematosus

  • Polymorphous light eruption (PMLE)


Laboratory Tests

  • Blood and urine tests are not helpful in diagnosis unless porphyria cutanea tarda is suggested by the presence of

    • Blistering

    • Scarring

    • Milia (white cysts 1–2 mm in diameter)

    • Skin fragility of the dorsal hands

    • Facial hypertrichosis

  • Eosinophilia may be present in chronic photoallergic responses



  • Medications should be suspected in cases of photosensitivity even if the particular medication (such as hydrochlorothiazide) has been used for months


  • When the eruption is vesicular or weepy, treatment is similar to that of any acute dermatitis, using cooling and soothing wet dressing

  • Mid-potency to high-potency topical corticosteroids are of limited benefit in sunburn reactions but may help in polymorphous light eruption and photoallergic reactions

  • Since the face is often involved, close monitoring for corticosteroid side effects is recommended


  • Aspirin may have some value for fever and pain of acute sunburn, as prostaglandins appear to play a pathogenetic role in the early erythema

  • Systemic corticosteroids in doses as described for acute contact dermatitis may be required for severe photosensitivity reactions

  • Hydroxychloroquine (5 mg/kg once daily) or immunosuppressives, such as azathioprine (50–300 mg once daily) or cyclosporine (3–5 mg/kg once daily) may be indicated in patients with chronic primary photodermatoses



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