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.
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Acute sunburn of face after a soccer match in a 15 year-old female.
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.
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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]
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; these are listed below:
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.[10]
Hydration: UVR causes erythema in moist skin more effectively than dry skin.[11]
Environmental reflection: Radiation is 80% reflected by snow and ice, compared with 15% by sand.[12]
Ozone coverage: Increased levels of ozone filter out more UVR.[12]
Altitude: Thinner atmosphere at higher altitudes absorbs less UVR.[12]
Latitude: Exposure is greater nearer the equator.[12]
Time of day: UVR exposure is greatest from 10 am to 4 pm, when the sun is highest in the sky.[12]
Season: In locations outside the tropics, UVR is much greater in summer than winter.[12]
Cloud cover: Light clouds attenuate UVR by 10%, which may not be enough to protect from sunburn.[12]
Previous reports have stated that about one third of US adults have a sunburn each year[13, 14] and about two thirds of US children have a sunburn each summer.[15] 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.[16]
International
Risk of sunburn is increased in regions that are closer to the equator and that are higher in altitude.[12]
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, 10, 17]
View Table
See Table
Sex
Surveys of US adults show that men have a slightly higher prevalence of sunburn than women.[13]
Age
Sunburn is more common in children than in adults.[14, 15] Easy sunburning during infancy may indicate a serious underlying disease, such as porphyria or xeroderma pigmentosum. Referral for further evaluation is prudent.[18]
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.
History and symptoms for sunburn may include the following:
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 peeling[8] (See the image below.)
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Subacute sunburn of shoulder with peeling in a 21-year-old male.
Assess for exposure to photosensitizing drugs. See Medscape Reference 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.[14, 19]
Sunburns may exacerbate chronic diseases such as chronic actinic dermatitis, herpes simplex, eczema, and lupus erythematosus.[18]
Sunburns may be associated with other heat-related illnesses, including dehydration, heat exhaustion, and heatstroke.
Long-term exposure of the skin can lead to multiple deleterious effects, including premature aging and wrinkling of the skin (dermatoheliosis), development of premalignant lesions (solar keratoses), and development of malignant tumors (eg, basal cell carcinoma, squamous cell carcinoma, melanoma).[2] A history of severe sunburn is associated with an increased risk of melanoma and other skin cancers, particularly in men.[22]
Patients with sunburn may be at risk for UV keratitis.[23]
Most sunburns, while painful, are not life threatening, and treatment is primarily symptomatic.[8]
Nonsteroidal anti-inflammatory drugs (NSAIDs) have antiprostaglandin effects and may relieve pain and inflammation, especially when given early. However, NSAIDs do not shorten the duration of sunburn.[24]
Cool soaks with water or Burrow solution (aluminum acetate solution) also provide temporary relief.[8, 25]
Fluid replacement (oral or intravenous) for severe erythema or concomitant fluid loss.[26]
Studies of emollients such as aloe vera have failed to demonstrate decreased recovery times, but these treatments may help with sunburn symptoms.[27]
Topical anesthetic sprays or creams may cause sensitization and consequent dermatitis and, therefore, should be avoided.[26]
Systemic steroids are sometimes used to shorten the course and to reduce the pain of sunburn when given early and in relatively high doses (equivalent to 40-60 mg/d of prednisone).[8] Although this is described in the literature, currently, there is no evidence to support this practice.[27]
Prescribe steroids for only a few days, with no need for a taper. In the presence of partial-thickness (second-degree) burn, steroids are best avoided because they increase the risk of infection. Topical steroids have not shown any clinical benefit when applied after UV exposure.[8, 28]
Inpatient care is indicated for severe burns, secondary infection, or control of severe pain. Indications for admission to a dedicated burn unit are the same as those for thermal burns. Indication for transfer to a burn unit are the same as for thermal burns (second-degree burns covering 25% of total body surface area in adults or 20% of total body surface area in patients aged < 10 y or >50 y).[20] Other criteria exist for body parts affected, please refer to Thermal Burns for a discussion of deeper thermal burns.
Outpatient care, with the following, is indicated for most cases of sunburn:
Consult a dermatologist if the diagnosis of sunburn is in doubt or for children who appear to burn easily. In the latter case, a more serious underlying disorder may be present.
Severe cases may require consultation with pediatricians or internists for hospital admission. Patients rarely require care in a dedicated burn unit.
Prevention is the most effective therapy for sunburn. Individual and community educational programs can be effective in decreasing overall sun exposure or increasing use of sunscreen or protective clothing.[29, 30]
Avoid sun exposure, especially during the period of peak solar radiation (from 10 am to 4 pm).[13]
Regularly use sunscreen with an adequate sun protection factor (SPF) for a given skin type. Note the following:
SPF is the ratio of the amount of UV energy needed to produce erythema on protected skin to the amount of UV energy needed to produce erythema on unprotected skin.[31]
Refer to the Table for recommended sunscreen levels for everyday protection and outdoor activity protection.
Apply at least 30 minutes prior to sun exposure, and reapply every 2-3 hours or after swimming, sweating, or toweling off.[31]
Apply for young children prior to exposure.
Use waterproof sunscreen when swimming or perspiring heavily.[31]
Apply at least 2 mg/cm2 of sunscreen to achieve the advertised SPF (about 30 mL is adequate coverage for an average adult's entire body). Most people apply one fifth of this amount.[32]
Physical barriers (eg, zinc oxide, titanium dioxide) provide excellent protection against UVA and UVB and are photostable.[17]
Chemical barriers are used in most sunscreens. Para-aminobenzoic acid (PABA) and PABA esters, UVB blockers, have fallen out of favor because of high rates of associated contact dermatitis and clothing staining. Other chemical UVB blocking agents include cinnamates and salicylates.[17]
Chemical UVA blockers include avobenzone (Parsol 1789) and the recently FDA-approved drometrizole trisiloxane and terephthalylidene (Mexoryl).[33]
Wear protective clothing, including wide-brimmed hat or sun visor. Clothing can be treated with over-the-counter products to increase protection from UV radiation.[21]
Specialized sun-protective clothing is available and usually states the SPF each garment affords.
The symptoms of minor sunburn can be relieved to some extent with cool compresses or a cool bath. Administration of nonprescription analgesics and NSAIDs for the treatment of pain and inflammation is recommended. Topical anesthetic sprays or creams may cause sensitization and consequent dermatitis and, therefore, should be avoided.[26]
Clinical Context:
Naproxen is used for relief of mild to moderate pain; it inhibits inflammatory reactions and pain by decreasing the activity of cyclooxygenase, which results in a decrease of prostaglandin synthesis.
Clinical Context:
Acetaminophen is the recommended analgesic in patients with documented hypersensitivity to aspirin or NSAIDs, in those with upper GI disease, or in those who are taking oral anticoagulants. Acetaminophen is effective in relieving mild to moderate acute pain; however, it has no peripheral anti-inflammatory effects. It may be preferred in elderly patients because of fewer GI and renal adverse effects.
Because they modify the body's immune response, corticosteroids are thought to decrease erythema, but they have little or no clinical utility for sunburn.
How is sunburn characterized?What is the pathophysiology of sunburn?What causes of sunburn?Which factors increase the risk for sunburn?What is the prevalence of sunburn in the US?Which geographic regions are at highest risk for sunburn?What are the Fitzpatrick categories of skin types and how are they used to prevent sunburn?How does the incidence of sunburn vary by sex?Which age groups are at highest risk for sunburn?What is the morbidity and mortality of sunburn?What should be included in patient education about sunburn?What are the signs and symptoms of sunburn?Which physical findings are characteristic of sunburn?What are complications of sunburn?What are the differential diagnoses for Sunburn?What is the role of lab studies in the workup of sunburn?What is the role of imaging studies in the workup of sunburn?What is the role of skin biopsy in the workup of sunburn?What is included in prehospital care for sunburn?What is included in the medical care treatment for sunburn?What is the role of steroids in the treatment of sunburn?When is inpatient care indicated for the treatment of sunburn?What is included in outpatient care for sunburn?Which specialist consultations may be beneficial in the management of patients with sunburn?How is sunburn prevented?Which medications are used in the treatment of sunburn?Which medications in the drug class Corticosteroids are used in the treatment of Sunburn?Which medications in the drug class Analgesic, Miscellaneous are used in the treatment of Sunburn?Which medications in the drug class Analgesic Nonsteroidal Anti-inflammatory Drug are used in the treatment of Sunburn?
Christopher M McStay, MD, Assistant Professor, Department of Emergency Medicine, New York University School of Medicine, Bellevue Hospital Center
Disclosure: Nothing to disclose.
Coauthor(s)
Ershad Elahi, MD, Resident Physician, Department of Emergency Medicine, Bellevue Hospital Center, New York
Disclosure: Nothing to disclose.
Specialty Editors
Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Received salary from Medscape for employment. for: Medscape.
Amin Antoine Kazzi, MD, Professor of Clinical Emergency Medicine, Department of Emergency Medicine, American University of Beirut, Lebanon
Disclosure: Nothing to disclose.
Chief Editor
Joe Alcock, MD, MS, Associate Professor, Department of Emergency Medicine, University of New Mexico Health Sciences Center
Disclosure: Nothing to disclose.
Additional Contributors
James Li, MD, Former Assistant Professor, Division of Emergency Medicine, Harvard Medical School; Board of Directors, Remote Medicine
Disclosure: Nothing to disclose.
Acknowledgements
The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous author, Amy Caron, MD, to the development and writing of this article.
References
Kochevar IE, Taylor CR. Photophysics, photochemistry and photobiology. Freedberg IM, ed. Fitzpatrick's Dermatology in General Medicine. 6th ed. New York, NY: McGraw-Hill; 2003. 1267-1275.
Walker SL, Hawk JL, Young AR. Acute effects of ultraviolet radiation on the skin. Freedberg IM, ed. Fitzpatrick's Dermatology in General Medicine. 6th ed. New York, NY: McGraw-Hill; 2003. 1275-1282.
Kramer DA, Shayne P. Sun-induced disorders. Schwartz GR, ed. Principles and Practice of Emergency Medicine. 4th ed. Baltimore, MD: Lippincott Williams & Wilkins; 1999. 1581.
World Health Organization. Ultraviolet radiation: global solar UV index. Fact sheet No. 271. August 2002. Available at http://www.who.int/uv/publications/en/GlobalUVI.pdf. Accessed: June 2, 2017.
Hawk JLM, Norris PG, Honigsmann H. Abnormal responses to ultraviolet radiation: idiopathic, probably immunologic, and photoexacerbated. Freedberg IM, ed. Fitzpatrick's Dermatology in General Medicine. 6th ed. New York, NY: McGraw-Hill; 2003. 1290-1295.
Gasparro FP, Brown D, Diffey BL, Knowland JS, Reeve V. Sun protective agents: formulations, effects and side effects. Freedberg IM, ed. Fitzpatrick's Dermatology in General Medicine. 6th ed. New York, NY: McGraw-Hill; 2003. 2344-2352.
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