Here Comes the Sunburn: An Update

Urgent message: The advent of warmer weather is a reminder that many otherwise sensible Americans fail to heed warnings to use adequate protection from the sun. The urgent care clinician can expect to see more patients presenting with varying degrees of sunburn.

Deepthi Samindla, MBBS, Beth Braig, BA, Mikayla L. Spangler, PharmD, Shailendra K. Saxena, MD, PhD
Introduction
Sunburn is an acute cutaneous inflammation to excessive exposure to solar ultraviolet (UV) radiation. About 30% to 40% of adults and 70% to 85% of children and adolescents in the United States experience an episode of sunburn every year.¹ It is estimated that 80% of a person’s sun exposure occurs before the age of 21.
²
Hence, lifestyle modifications early in life play a crucial role in the prevention of sunburn and other, long-term, harmful effects of solar radiation.
In this article we provide updated information about sunburn’s symptoms, pathogenesis, treatment, and prevention.

Pathogenesis

Solar UV rays can be classified into UV-A (340 nm to 400 nm) and UV-B (290 nm to 320 nm).
UV-B lights is 1,000 times more erythemogenic than UV-A and can induce DNA mutagenesis; therefore, it is more damaging to the skin.

DNA damage, induction of p53, and generation of reactive oxygen species seem to be the major mechanisms of UV-B related skin damage.

Histologically, sunburn affects the stratum spinosum of skin epithelium. Dyskeratotic cells, also known as sunburn cells, are usually seen in this layer within 24 hours of exposure to UV light.
The pathogenesis of UV radiation related skin damage is summarized in Figure 1.

Risk Factors

The two major factors determining the development of sunburn are the amount and duration of exposure to sunlight and patient susceptibility.

Numerous environmental and biologic factors increase susceptibility to sunburn (Table 1). A history of sunburn, especially following low-intensity sunlight exposure, is a strong predictor of recurrent sunburn.
Contrary to popular belief, cloudy days are not associated with decreased risk of sunburn, as 80% of the UV rays can penetrate the clouds. In addition, for every 100 feet above sea level, radiation increases 4% to 5%.²

A simple classification of skin phototypes based on response to initial sun exposure proposed by Fitzpatrick is depicted in Table 2.³

Clinical Manifestation and Diagnosis

Clinical manifestations of sunburn can range from painless erythema to blistering and second-degree burns (Figure 2 and Figure 3).

Common complaints include pain, redness, burning, blistering, and swelling. Physical signs include erythema, warmth, tenderness, edema, and blistering. Erythema develops three to four hours after exposure and peaks around 12 to 24 hours. Scaling and desquamation are late signs and are often noted four to seven days after exposure. Diagnosis is usually based on history of exposure to sunlight, typical symptoms, and the characteristics appearance of sun-exposed skin.⁴

Prevention

The following measures may help prevent sunburn and other undesirable effects of sunlight (i.e., phootaging, actinic keratosis, and dermatologic malignancies such as melanoma and basal cell carcinoma).²

1. Avoidance. Avoiding direct exposure to sunlight, especially during summer between 10 a.m. and 4 p.m. Patients should be educated that cloudy days offer no protection against harmful UV radiation.
2. Sun-protective clothing. Clothing filters out the sun’s rays. Covering up with a wide brimmed hat, sunglasses with appropriate sun blockade, and wearing loose-fitting clothing with long sleeves provide sun protection.

Summer clothing usually provides limited protection because of the looseness of the weave, typically ranging from 2 to 6.5 Sun Protection Factor (SPF); SPF estimates the protection offered by clothing or sunscreen or sunblock against sunburn. Synthetic materials used in sun-protective garments have tighter-woven fabric and provide greater protection. These specialized garments demonstrate high solar protection in studies despite color or moisture content.^{2, 5}

3. Sunscreens. The current gold standard for photo protection is sunscreen.² If an individual develops erythema after 10 minutes of direct sun exposure, the use of SPF 15 sunscreen would prevent erythema from a similar intensity exposure of about 150 minutes. Sunscreens are classified as either physical/inorganic or chemical/organic sunscreens.

Physical sunscreens contain inert minerals such as titanium dioxide, zinc oxide, or talc and work by reflecting UV-A and UV-B rays away from the skin. Aesthetically unappealing qualities limit their use.

Chemical sunscreens are sub-classified based on their ability to absorb UV-A, UV-B, or both. Table 3 lists the various chemicals used in sunscreens, as well as their spectrum of protection.⁶ Most sunscreens available today have a combination of UV-A and UV-B protective chemicals.

Choosing an appropriate sunscreen from the wide array of products is challenging. Certain products have received a Seal of Recommendation from the Skin Cancer Foundation, awarded to products that have proven to safely and sufficiently “aid in the prevention of sun-induced damage to the skin.”⁷ A minimum SPF of 15 for adults and 25 for children is recommended.

Use of sunscreens in children < 6 months of age is not recommended.⁸
Products with an SPF above 30 offer little additional benefit and may expose the individual to potentially harmful levels of chemicals.^{2, 6,8}

Uniform and proper application of an appropriate sunscreen is essential to achieve full benefits and is outlined in Table 4.⁸

Treatment

Symptomatic therapy is the mainstay of management of acute sunburns. A number of treatments aimed at altering the course of sunburn have been explored, but no conclusive evidence supporting their use exists at present.⁹

NSAIDs

The use of NSAIDs has been studied in the treatment of sunburn. Both topical (e.g., diclofenac 0.1% gel) and oral NSAIDs have been shown to decrease erythema and pain. However, the beneficial effects, especially of topical preparations, decrease after the initial 24 hours.

Corticosteroids

Although corticosteroids have anti-inflammatory effects, neither topical nor systemic use has been shown to effect clinical improvement compared with placebo.⁹ Similarly, prednisone 80 mg given 24 hours before exposure has not been shown to improve symptoms when compared with placebo.

Combining topical corticosteroids with oral NSAIDs has been shown to be more efficacious than either agent alone.

Emollients

Limited data exists on the use of emollients after sunburn.

Antioxidants

The role of antioxidants in prevention and treatment of sunburn remains questionable. No definitive evidence exists to justify the widespread use of substances such as vitamins, melatonin, or thiamazole for erythema due to sun exposure.⁹

Summary of Recommendations
The following constitutes a basic guide for patients (and providers) wishing to avoid excessive exposure to solar UV radiation.

• Avoid the sun, especially between 10 a.m. and 4 p.m.
• Wear protective clothing, including a hat, long-sleeved shirt, and long pants made of closely woven fabrics.
• use a sunscreen with an SPF if 15 to 30 for children over 6 months of age and for adults.
• Wear sunglasses that protect from UV-A and UV-B light.
• Beware of reflected light from sand, cement, water, and snow.
• Be more careful at high altitudes.
• Avoid the sun if you are taking certain medications of have a condition that makes you photosensitive.
• The only treatment currently recommended is symptomatic.

References

1. Davis KJ, Cokkinides VE, Weinstock MA, et al. Summer sunburn and sun exposure among U.S. youths age 11 to 18: National prevalence and associated factors. Pediatrics. 2002; 110: 27-35.
2. Sheer B. Issues in summer safety: A call for sun protection. Pediatr Nurs. 199; 25: 319-320, 323-325.
3. Fitzpatrick TB. The validity and practicality of sun-reactive skin types I though VI. Arch Dermatol. 1988; 124: 869-871.
4. Walker SL, Hawk JL, Young AR. Acute effects of ultraviolet radiation on the skin. In: Freedberg IM, ed. Fitzpatrick’s Dermatology in general Medicine. 6^th ed. New York, NY: McFraw-Hill; 2003: 1275-1282.
5. Maguire-Eisen M, Rothman K, Demierre MF. The ABCs of sun protection for children. Dermatol Nurs. 2005; 17: 419-422, 431-433.
6. Lowe NJ. An overview of ultraviolet radiation, sunscreens, and photo-induced dermatoses. Dermatol Clin. 2006; 24: 9-17.
7. The Skin Cancer Foundation Seal of Recommendation. http://www.skincare.org/seal-of-recommendation/. Accessed 7/27/09.
8. Moloney FJ, Collins S, Murphy GM. Sunscreens: Safety, efficacy, and appropriate use. Am J Clin Dermatol. 2002; 31: 185-191.
9. Han A, Maibach HI. Management of acute sunburn. Am J Clin Dermatolol. 2004; 5: 39-47.

Shailendra K. Saxena, MD, PhD

Professor at Creighton University Medical School, Editorial Board Member at The Journal of Urgent Care Medicine