Sunburn is an acute cutaneous inflammatory reaction that follows excessive exposure of the skin to ultraviolet (UV) 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.)
View Image
Acute sunburn on face of 15 year-old female after soccer match.
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 UV 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 1 hour after UVR exposure, mast cells release preformed mediators, including histamine, serotonin, and tumor necrosis factor (TNF), 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 (see the image below).[6, 7] Erythema usually occurs 3-4 hours after exposure, with peak levels at 24 hours.[8]
View Image
Note apoptotic sunburn cells in the epidermis. Image from David Shum, MD, Division of Dermatology, University of Western Ontario.
UVR exposure that is less intense or of shorter duration exposure 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 the following two phases:
Immediate pigment darkening - This 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 - This 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 through 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 UV spectrum can be divided into the following segments[1] :
Ultraviolet A (UVA)-I, 340-400 nm
UVA-II, 320-340 nm
Ultraviolet B (UVB), 290-320 nm
Ultraviolet C (UVC), 200-290 nm
Solar UVR of wavelengths shorter than 290 nm is filtered out or absorbed in the outer atmosphere and is not encountered at sea level.[1] Shorter-wavelength UVB rays are much more effective at inducing erythema than UVA rays are and thus are the principal cause of sunburn.[1, 10] However, UVA constitutes the majority of the UVR reaching the surface of the earth (~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 varies according to skin type.[2]
Multiple factors influence UVR-induced erythema, including the following[2, 11, 12, 13] :
Wavelength - UVB is more erythemogenic than UVA
Skin type/pigmentation - Compared with patients who have type I-II skin, patients who have type IV-V skin require three to five times more UVR exposure to cause erythema
Hydration - UVR causes erythema more effectively in moist skin than in dry skin
Environmental reflection - Radiation is 80% reflected by snow and ice but only 15% reflected by sand
Ozone coverage - Increased levels of ozone filter out more UVR
Altitude - Thinner atmosphere at higher altitudes absorbs less UVR
Latitude - Exposure is greater nearer the equator
Time of day - UVR exposure is greatest from 10:00 AM to 4:00 PM, when the sun is highest in the sky
Season - In locations outside the tropics, UVR is much greater in summer than in winter
Cloud cover - Light clouds attenuate UVR by 10%, which may not be enough to protect from sunburn
Previous reports have stated that about one third of US adults have a sunburn each year,[14, 15] and about two thirds of US children have a sunburn each summer.[16] 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.[17] Rural US residents may be at higher risk than urban residents.[18]
Risk of sunburn is increased in regions that are closer to the equator and that are higher in altitude.[13]
Age-, sex-, and race-related demographics
Sunburn is more common in children than in adults.[16] Easy sunburning during infancy may indicate a serious underlying disease, such as porphyria or xeroderma pigmentosum. Referral for further evaluation is prudent.
Surveys of US adults show that men have a slightly higher prevalence of sunburn than women.[14]
Lighter-skinned individuals are affected more frequently and severely. Skin types are traditionally classified into one of six Fitzpatrick categories, based on an individual's tendency to tan, to burn, or both (see Table 1 below).[2, 11, 19]
Table 1. Fitzpatrick Skin Types and Recommended Sunscreen Sun Protection Factor (SPF) Levels
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 are related primarily to the development of cutaneous neoplasms, including basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and malignant melanoma.[2] For more information on skin cancers, see the Skin Cancer Resource Center.
Patients should be educated regarding the short- and long-term complications of sunburn (see Complications). They should also be instructed in means of preventing sunburn (see Prevention).[10] There is clearly a need for better education in this area. A narrative review of 24 studies addressing skin cancer–related knowledge, attitudes, beliefs, and prevention practices among beachgoers and sunbathers found that 21-22.8% did not use sun protection and that 62% had experienced a blistering sunburn at some point.[20]
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 that 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)
View Image
Subacute sunburn on shoulder of 21-year-old male, with peeling.
It is important to inquire about possible exposure to photosensitizing drugs (see Drug-Induced Photosensitivity), as well as about possible heavy alcohol use, which is associated with sunburning.[21, 22]
Patients at highest risk for sunburn typically have fair skin, blue eyes, and red or blond hair.[11]
The acute inflammatory response, which includes the following, 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) burn[23]
In severe cases, fever may be present.[8]
Ultraviolet (UV) radiation (UVR) may be transmitted through clothing, especially when the clothing is wet; consequently, sunburn may occur even in skin covered by clothing.[24]
Delayed scaling and desquamation occur 4-7 days after exposure.[8]
Sunburns may exacerbate chronic diseases (eg, chronic actinic dermatitis, herpes simplex, eczema, and lupus erythematosus).
Sunburns may be associated with other heat-related illnesses (eg, dehydration, heat exhaustion, and heatstroke).
Long-term exposure to UVR can lead to multiple deleterious effects on the skin, including premature aging and wrinkling (dermatoheliosis), development of premalignant lesions (solar keratoses), and development of malignant tumors (eg, basal cell carcinoma [BCC], squamous cell carcinoma [SCC], and melanoma).[2] A history of severe sunburn is associated with an increased risk of melanoma and other skin cancers, particularly in men.[25]
Patients with sunburn may be at risk for UV keratitis.[26]
No laboratory tests or imaging studies are indicated for uncomplicated cases of sunburn. However, skin biopsy may be indicated if the diagnosis is in doubt or it is necessary to exclude other diseases in the differential diagnosis.
The majority of sunburns, though painful, are not life-threatening, and their treatment is primarily symptomatic.[8] Generally, prehospital care involves providing simple first aid to treat patient symptoms. In severe cases, second-degree burns may develop, potentially necessitating aggressive fluid resuscitation and skin care.
Nonsteroidal anti-inflammatory drugs (NSAIDs) have antiprostaglandin effects and may relieve pain and inflammation, especially when given early; however, they do not shorten the duration of sunburn.[27] Ibuprofen is usually the drug of choice for the treatment of mild-to-moderate pain, if no contraindications are present. Naproxen and aspirin are also used.
For patients with documented hypersensitivity to aspirin or other NSAIDs, those with upper gastrointestinal (GI) disease, or those taking oral anticoagulants, acetaminophen is the recommended analgesic. It may be preferred in elderly patients because it has fewer GI and renal adverse effects
Cool soaks with water or Burrow solution (aluminum acetate solution) also provide temporary relief.[8, 28]
Fluid replacement (oral or intravenous) is warranted for severe erythema or concomitant fluid loss.[29]
Studies of emollients such as aloe vera have not demonstrated decreased recovery times in sunburn, but these treatments may mitigate symptoms.[30]
Topical anesthetic sprays or creams may cause sensitization and consequent dermatitis and therefore should be avoided.[29]
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 prednisone 40-60 mg/d).[8] Although this practice has been described in the literature, evidence to support it has been lacking.[30]
Steroids, if prescribed, should be used for only a few days, with no need for a taper. In the presence of a partial-thickness (second-degree) burn, steroids are best avoided, in that they increase the risk of infection. Topical application of steroids after ultraviolet (UV) exposure has not been demonstrated to yield clinical benefit.[8, 31]
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 for sunburns as 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 [TBSA] in adults or 20% of TBSA in patients aged < 10 y or >50 y).[23] (For a discussion of deeper thermal burns, see Thermal Burns.)
Outpatient care, including the following, is indicated for most cases of sunburn:
Prevention is the most effective therapy for sunburn.[10] Individual and community educational programs can be effective in decreasing overall sun exposure or increasing use of sunscreen or protective clothing.[32, 33]
Sun exposure should be avoided, especially during the period of peak solar radiation (from 10:00 AM to 4:00 PM).[14]
Sunscreen with an adequate sun protection factor (SPF) for a given skin type should be used on a regular basis. 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.[34] Recommended sunscreen levels for everyday protection and outdoor activity protection may be found in Table 1 (see Epidemiology).
Sunscreen should be applied at least 30 minutes before sun exposure (especially for young children) and should be reapplied every 2-3 hours or after swimming, sweating, or toweling off.[34] Waterproof sunscreen should be used if one is swimming or perspiring heavily.[34] To achieve the advertised SPF, it is necessary to apply at least 2 mg/cm2 (~30 mL is adequate coverage for an average adult's entire body); however, most people apply only about one fifth of this amount.[35]
Sunscreens that include physical barriers (eg, zinc oxide or titanium dioxide) provide excellent protection against ultraviolet A (UVA) and ultraviolet B (UVB) and are photostable.[19] Most sunscreens use chemical barriers. 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 blockers include cinnamates and salicylates.[19] Chemical UVA blockers include avobenzone, drometrizole trisiloxane, and ecamsule (terephthalylidene).[36]
Protective clothing should be worn outdoors, including wide-brimmed hat or sun visor. Clothing can be treated with over-the-counter products to increase protection from UV radiation (UVR).[24] Specialized sun-protective clothing is readily available, and each garment is usually labeled with the SPF it affords.
Some studies have found topical melatonin, alone or combined with vitamin C or D, to be an effective photoprotective agent.[37]
A dermatologist should be consulted if the diagnosis of sunburn is in doubt or if the patient is a child who appears to burn easily. In the latter case, a more serious underlying disorder may be present.
Severe cases may necessitate consultation with pediatricians or internists for hospital admission. Only rarely will patients require care in a dedicated burn unit.
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 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?How is sunburn prevented?Which specialist consultations may be beneficial in the management of patients with sunburn?What is included in prehospital care for sunburn?Which medications are used in the treatment of sunburn?Which medications in the drug class Analgesics, Other 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 NSAIDs are used in the treatment of Sunburn?
Christopher M McStay, MD, FAWM, FACEP, Associate Professor of Emergency Medicine, Chief of Emergency Department Clinical Operations, University of Colorado School of Medicine
Disclosure: Nothing to disclose.
Coauthor(s)
Ershad Elahi, MD, Clinical Attending Physician, Emergency Department, Osceola Regional Medical Center, Envision Physician Services; Emergency Physician, StationMD
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
Rünger TM. Cutaneous photobiology. Kang S, Amagai M, Bruckner AL, Enk AH, Margolis DJ, McMichael AJ, et al, eds. Fitzpatrick's Dermatology. 9th ed. New York: McGraw-Hill; 2019. Vol 1: 265-88.
Lim HW. Phototoxicity and photoallergy. Kang S, Amagai M, Bruckner AL, Enk AH, Margolis DJ, McMichael AJ, et al, eds. Fitzpatrick's Dermatology. 9th ed. New York: McGraw-Hill; 2019. Vol 1: 1657-65.
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.
Global solar UV index. World Health Organization. Available at https://iris.who.int/bitstream/handle/10665/42459/9241590076.pdf. 2002; Accessed: March 10, 2025.
){kind=link}
){kind=link}
){kind=link}