Introduction
Background
Sunburn is an acute cutaneous inflammatory reaction that follows excessive exposure of the skin to ultraviolet radiation (UVR). UVR exposure can come from a variety of sources, including sun, tanning beds, phototherapy lamps, and arc lamps.1 Long-term adverse health effects of repeated exposure to UVR are well described but are beyond the scope of this article. Sunburn is generally classified as a superficial or first-degree burn.
Acute sunburn of face after a soccer match in a 15 year-old female.
Pathophysiology
Exposure to solar radiation has the beneficial effects of stimulating the cutaneous synthesis of vitamin D and providing radiant warmth. Unfortunately, when the skin is subjected to excessive radiation in the ultraviolet range, deleterious effects may occur. The most conspicuous is acute sunburn or solar erythema.2
Initially, UVR causes vasodilation of cutaneous blood vessels, resulting in the characteristic erythema.Within an hour of UVR exposure, mast cells release preformed mediators including histamine, serotonin, and tumor necrosis factor, leading to prostaglandin and leukotriene synthesis.2,4 Cytokine release additionally contributes to the inflammatory reaction, leading to an infiltrate of neutrophils and T lymphocytes.5 Within 2 hours after UV exposure, damage to epidermal skin cells is seen. Both epidermal keratinocytes ("sunburn cells") and Langerhans cells undergo apoptotic changes as a consequence of UVR-induced DNA damage.6,7 Erythema usually occurs 3-4 hours after exposure, with peak levels at 24 hours.8
Note the apoptotic sunburn cells in the epidermis. Photograph courtesy of David Shum, MD, Division of Dermatology, University of Western Ontario.
Less intense or shorter-duration exposure to UVR results in an increase in skin pigmentation, known as tanning, which provides some protection against further UVR-induced damage.9 The increased skin pigmentation occurs in 2 phases: (1) immediate pigment darkening and (2) delayed tanning. Immediate pigment darkening occurs during exposure to UVR and results from alteration of existing melanin (oxidation, redistribution). It may fade rapidly or persist for several days. Delayed tanning results from increased synthesis of epidermal melanin and requires a longer period of time to become visible (24-72 h). With repeated exposure to UVR, the skin thickens, primarily due to epidermal hyperplasia with thickening of the stratum corneum. UVR exposure also suppresses cutaneous cell-mediated immunity, contributing to nonmelanoma skin cancer and infectious disease development.2
Frequency
United States
About one third of US adults have a sunburn each year10,11 , and about two thirds of US children have a sunburn each summer.12
International
Risk of sunburn is increased in regions that are closer to the equator and that are higher in altitude.13
Mortality/Morbidity
- Uncomplicated sunburn is associated with minimal short-term morbidity. Most cases resolve spontaneously with no significant sequelae.
- In rare cases, sunburn may be so severe and diffuse that it results in second-degree burns, dehydration, or secondary infection.8
- Morbidity and mortality associated with long-term sun exposure is related primarily to the development of cutaneous neoplasms, including basal cell carcinoma, squamous cell carcinoma, and malignant melanoma.2 For more information on skin cancers, see Medscape's Skin Cancer Resource Center.
Race
Lighter-skinned individuals are affected more frequently and severely. Skin types are traditionally classified into the following Fitzpatrick categories, based on an individual's tendency to tan, burn, or both (see the Table below).Fitzpatrick Skin Types and Recommended Sunscreen Sun Protection Factor (SPF) Levels
14,2,15
Open table in new window
Table
| Skin Type | Description | Skin Color | Routine SPF | SPF for Outdoor Activity |
| I | Always burns, never tans | White | 15 | 25-30 |
| II | Always burns, tans minimally | White | 12-15 | 25-30 |
| III | Burns minimally, tans slowly | White | 8-10 | 15 |
| IV | Burns minimally, tans well | Olive | 6-8 | 15 |
| V | Rarely burns, tans profusely/darkly | Brown | 6-8 | 15 |
| VI | Rarely burns, always tans | Black | 6-8 | 15 |
| Skin Type | Description | Skin Color | Routine SPF | SPF for Outdoor Activity |
| I | Always burns, never tans | White | 15 | 25-30 |
| II | Always burns, tans minimally | White | 12-15 | 25-30 |
| III | Burns minimally, tans slowly | White | 8-10 | 15 |
| IV | Burns minimally, tans well | Olive | 6-8 | 15 |
| V | Rarely burns, tans profusely/darkly | Brown | 6-8 | 15 |
| VI | Rarely burns, always tans | Black | 6-8 | 15 |
Sex
Surveys of US adults show that men have a slightly higher prevalence of sunburn than women.10
Age
Sunburn is more common in children than in adults.12,11
Clinical
History
- Recent sun exposure or outdoor activity; outdoor occupations or hobbies; use of indoor tanning equipment
- Erythema develops after 3-4 hours and peaks at 12-24 hours.8
- Pain
- Possible fever, chills, malaise, nausea, or vomiting in severe cases
- Blistering
- Erythema that resolves over 4-7 days, usually with skin scaling and peeling8
Subacute sunburn of shoulder with peeling in a 21-year-old male.
- Assess for exposure to photosensitizing drugs. See eMedicine article Drug-Induced Photosensitivity for an in-depth discussion and list of common photosensitizing drugs.
- Assess for heavy alcohol use, which is associated with sunburning.11,16
Physical
- Patients at highest risk typically have fair skin, blue eyes, and red or blond hair.14
- The acute inflammatory response is greatest 12-24 hours after exposure.8
- Erythema
- Warmth
- Tenderness
- Edema
- Blistering (severe cases), a sign of either a superficial partial-thickness or deep partial-thickness (second-degree) burn17
- Fever can present in severe cases.8
- UVR may be transmitted through clothing, especially when wet, so sunburn may occur under clothed skin.18
- Delayed scaling and desquamation occurs 4-7 days after exposure.8
Causes
- Sunburn is caused by excessive exposure of the skin to UVR.
- The ultraviolet spectrum can be divided into ultraviolet A-I (UVA-I), 340-400 nm; ultraviolet A-II (UVA-II), 320-340 nm, ultraviolet B (UVB), 290-320 nm; and ultraviolet C (UVC), 200-290 nm.1
- Solar UVR of wavelengths shorter than 290 nm are filtered out or absorbed in the outer atmosphere and are not encountered at sea level.1
- Shorter wavelength UVB rays are much more effective at inducing erythema than UVA rays and, therefore, are the principal cause of sunburn.1
- However, UVA comprises the majority of UVR reaching the surface of the earth (about 95-98% at midday) and, therefore, accounts for a significant percentage of the immediate and long-term cutaneous effects of UVR.1
- The minimal single dose of UVR (energy per unit area) required to produce erythema after 24 hours at an exposed site is known as the minimal erythema dose (MED). This dose differs by skin type.2
- Multiple factors influence UVR-induced erythema.
- Wavelength: UVB is more erythemogenic than UVA.2
- Skin type/pigmentation: Compared with type I-II skin, patients with type IV-V skin require 3-5 times more UVR exposure to cause erythema.14
- Hydration: UVR causes erythema in moist skin more effectively than dry skin.19
- Environmental reflection: Radiation is 80% reflected by snow and ice, compared with 15% by sand.13
- Ozone coverage: Increased levels of ozone filter out more UVR.13
- Altitude: Thinner atmosphere at higher altitudes absorbs less UVR.13
- Latitude: Exposure is greater nearer the equator.13
- Time of day: UVR exposure is greatest from 10 am to 4 pm, when the sun is highest in the sky.13
More on Sunburn |
 Overview: Sunburn |
| Differential Diagnoses & Workup: Sunburn |
| Treatment & Medication: Sunburn |
| Follow-up: Sunburn |
| Multimedia: Sunburn |
| References |
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References
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Walker SL, Hawk JL, Young AR. Acute effects of ultraviolet radiation on the skin. In: Freedberg IM, ed. Fitzpatrick's Dermatology in General Medicine. 6th ed. New York, NY: McGraw-Hill; 2003:1275-1282.
Walsh LJ. Ultraviolet B irradiation of skin induces mast cell degranulation and release of tumour necrosis factor-alpha. Immunol Cell Biol. Jun 1995;73(3):226-33. [Medline].
Terui T, Takahashi K, Funayama M, Terunuma A, Ozawa M, Sasai S, et al. Occurrence of neutrophils and activated Th1 cells in UVB-induced erythema. Acta Derm Venereol. Jan-Feb 2001;81(1):8-13. [Medline].
Clydesdale GJ, Dandie GW, Muller HK. Ultraviolet light induced injury: immunological and inflammatory effects. Immunol Cell Biol. Dec 2001;79(6):547-68. [Medline].
Van Laethem A, Claerhout S, Garmyn M, Agostinis P. The sunburn cell: regulation of death and survival of the keratinocyte. Int J Biochem Cell Biol. Aug 2005;37(8):1547-53. [Medline].
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Centers for Disease Control and Prevention (CDC). Sunburn prevalence among adults--United States, 1999, 2003, and 2004. MMWR Morb Mortal Wkly Rep. Jun 1 2007;56(21):524-8. [Medline]. [Full Text].
Brown TT, Quain RD, Troxel AB, Gelfand JM. The epidemiology of sunburn in the US population in 2003. J Am Acad Dermatol. Oct 2006;55(4):577-83. [Medline].
Cokkinides V, Weinstock M, Glanz K, Albano J, Ward E, Thun M. Trends in sunburns, sun protection practices, and attitudes toward sun exposure protection and tanning among US adolescents, 1998-2004. Pediatrics. Sep 2006;118(3):853-64. [Medline].
Ultraviolet radiation: global solar UV index. Fact sheet No. 271. August 2002. World Health Organization. Available at http://www.who.int/mediacentre/factsheets/fs271/en/index.html.
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Bickers DR. Sun-induced disorders. Emerg Med Clin North Am. Nov 1985;3(4):659-76. [Medline].
Rapaport MJ, Rapaport V. Preventive and therapeutic approaches to short- and long-term sun damaged skin. Clin Dermatol. Jul-Aug 1998;16(4):429-39. [Medline].
Han A, Maibach HI. Management of acute sunburn. Am J Clin Dermatol. 2004;5(1):39-47. [Medline].
Faurschou A, Wulf HC. Topical corticosteroids in the treatment of acute sunburn: a randomized, double-blind clinical trial. Arch Dermatol. May 2008;144(5):620-4. [Medline].
Dietrich AJ, Olson AL, Sox CH, Stevens M, Tosteson TD, Ahles T, et al. A community-based randomized trial encouraging sun protection for children. Pediatrics. Dec 1998;102(6):E64. [Medline].
Norman GJ, Adams MA, Calfas KJ, Covin J, Sallis JF, Rossi JS, et al. A randomized trial of a multicomponent intervention for adolescent sun protection behaviors. Arch Pediatr Adolesc Med. Feb 2007;161(2):146-52. [Medline].
Gasparro FP, Brown D, Diffey BL, Knowland JS, Reeve V. Sun protective agents: formulations, effects and side effects. In: Freedberg IM, ed. Fitzpatrick's Dermatology in General Medicine. 6th ed. New York, NY: McGraw-Hill; 2003:2344-2352.
Autier P, Boniol M, Severi G, Dore JF,. Quantity of sunscreen used by European students. Br J Dermatol. Feb 2001;144(2):288-91. [Medline].
Maier T, Korting HC. Sunscreens - which and what for?. Skin Pharmacol Physiol. Nov-Dec 2005;18(6):253-62. [Medline].
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Further Reading
Keywords
sunburn, sun burn, erythema solare, ultraviolet radiation, UVR, solar erythema, first-degree burn, superficial burn, second-degree burn, dehydration, shock, squamous cell carcinoma, basal cell carcinoma, malignant melanoma, photosensitizing drugs, blistering, UVA, UVB, minimal erythema dose, MED
