Photodermatitis
Basics
Description
- 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
Epidemiology
Incidence
- PLE usually occurs after the first intense exposure to the sun in the spring or summer.
- Predominant age: all ages
- Predominant sex: male = female
Prevalence
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.
Genetics
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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Citation
Domino, Frank J., et al., editors. "Photodermatitis." 5-Minute Clinical Consult, 33rd ed., Wolters Kluwer, 2025. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116454/all/Photodermatitis.
Photodermatitis. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2025. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116454/all/Photodermatitis. Accessed November 7, 2024.
Photodermatitis. (2025). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (33rd ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116454/all/Photodermatitis
Photodermatitis [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2025. [cited 2024 November 07]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116454/all/Photodermatitis.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC
T1 - Photodermatitis
ID - 116454
ED - Domino,Frank J,
ED - Baldor,Robert A,
ED - Golding,Jeremy,
ED - Stephens,Mark B,
BT - 5-Minute Clinical Consult, Updating
UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116454/all/Photodermatitis
PB - Wolters Kluwer
ET - 33
DB - Medicine Central
DP - Unbound Medicine
ER -