Sunburn

Updated: Sep 08, 2016
  • Author: Christopher M McStay, MD; Chief Editor: Joe Alcock, MD, MS  more...
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Overview

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. Most sunburns are classified as superficial or first-degree burns.

See the image below.

Acute sunburn of face after a soccer match in a 15 Acute sunburn of face after a soccer match in a 15 year-old female.
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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]

The principal injury responsible for sunburn is direct damage to DNA by UVR, resulting in inflammation and apoptosis of skin cells. [3] Sunburn inflammation 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]

See the image below.

Note the apoptotic sunburn cells in the epidermis. 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, which might contribute to nonmelanoma skin cancer and certain infections. [2]

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Epidemiology

Frequency

United States

Previous reports have stated that about one third of US adults have a sunburn each year [10, 11] and about two thirds of US children have a sunburn each summer. [12] The US Centers for Disease Control and Prevention (CDC) reported in 2012 that just over 50% of all adults reported at least one sunburn in the past 12 months and that just over 65% of whites aged 18-29 years reported at least one sunburn in the past 12 months. [13]

International

Risk of sunburn is increased in regions that are closer to the equator and that are higher in altitude. [14]

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).

Table. Fitzpatrick Skin Types and Recommended Sunscreen Sun Protection Factor (SPF) Levels [2, 15, 16] (Open Table in a new window)

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. [11, 12] Easy sunburning during infancy may indicate a serious underlying disease, such as porphyria or xeroderma pigmentosum. Referral for further evaluation is prudent. [17]

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Prognosis

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.

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Patient Education

Educate patients on the short- and long-term complications (see Complications).

Educate patients on prevention of sunburn (see Deterrence/Prevention).

For patient education resources, see the patient education article Sunburn.

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