Sunburn is the skin’s inflammatory response to excessive ultraviolet radiation (UVR) exposure from natural sunshine or artificial sources such as tanning beds or phototherapy devices. A sunburn is an acute, self-limited skin condition that can result from skin damage caused by both UVB light and/or UVA light; however, the skin is most susceptible to sunburn from the UVB range light (280 to 320 nm). Sunburns usually resolve within seven days, and the severity of sunburns depends on a variety of factors including genetic susceptibility, intensity and duration of UVR exposure, predisposing conditions, and others. People who are more susceptible to sunburns are also at greater risk for melanoma skin cancer.[2,3]Sunburn is especially common amongst teenagers and young adults, with almost 70% of adolescents aged 11 to 18 and 50% of adults reporting a sunburn the previous year.[4,5]
A few factors important to sunburns:
- Susceptibility to sunburn is highly variable from person to person, with individual phenotypic characteristic playing an important role in someone’s risk for sunburn. People who have fair or light skin, blue eyes, and naturally blonde or red hair are at greatest risk for developing sunburn after UVR exposure.
- A measurement called the minimum erythema dose (MED) is used to assess someone’s susceptibility to sunburn, and is considered the threshold for sunburn. The MED is the lowest dose of UVR exposed to the skin that produces visible redness in the skin within 24 hours. On average, lighter skin types have a lower MED than darker skin types. People with lighter skin burn much more easily, while people with darker skin types tan more easily.
- Natural sunlight contains mainly UVA rays, along with a lesser amount of UVB. As the ratio of UVB to UVA increases, the risk for sunburn increases.
- Biochemical and cellular changes occurs in the outer layer of skin (epidermis) during the sunburn response. First, the small vessels in the skin undergo vasodilation and skin cells called keratinocytes undergo cell death, called apoptosis. Visible redness occurs within 6 hours after exposure, and peaks between 12 and 24 hours as numerous inflammatory molecules and cells migrate into the skin.
- Some diseases can mimic sunburns, such as the classic butterfly rash that appears in people with systemic lupus erythematosus after sunlight exposure.
- Clinical manifestations of sunburn can range from mild redness to severe redness and blistering.
- A blistering sunburn indicates that a partial-thickness burn has occurred.
- In areas of sunburn, the skin usually becomes more sensitive to pressure and heat.
- Severe sunburns can be accompanied by headache, nausea, vomiting, and even fever.
- Redness from sunburn usually resolves within three to seven days, but blisters take up to 10 days to heal.
- Even after the sunburn resolves, some people may have residual brown spots, called solar lentigines.
Soaps and Creams
- Certain skin care products, such as those containing benzoyl peroxide, alpha-hydroxy acids (AHAs), and retinoids can make the skin more sensitive to sunburn.
- The skin may also be at increased risk for sunburn following exfoliation use, microdermabrasion, or chemical peels.
Some oral and topical medications can make the skin photosensitized and more susceptible to sunburn. People taking photosensitizing medications may have an exaggerated sunburn reaction, consisting of burning, redness, and swelling in minutes after UVR exposure.
- Oral photosensitizing medications, such as doxycycline, antihistamines, furosemide, and many others can increase the risk for sunburn.
- Topical photosensitizing medications, such as benzoyl peroxide (an anti-acne treatment) can increase sun sensitivity.
People living closest to the equator are at greater risk for sunburn, since this is where sunburn causing UVB rays are the most intense.
Time of day
Sunburn is most likely to occur around noon, rather than early morning or late afternoon. However, sunburn can still occur throughout the day.
- Snow can reflect up to 90% of sunlight, so people outdoors in the snow are at increased risk for sunburn, and people at higher altitudes are also at increased risk.
- Sand and water also reflect a moderate amount of sunlight, making the sunlight exposure more intense with a greater risk for sunburn.
Wet skin is more susceptible to sunburn than dry skin. Wet skin tends to dissipate heat faster and this may serve as a false sense of protection.
There are reports that people who drink alcohol while exposed to the sun are at greater risk for sunburn.[16,17]
People with naturally light or fair skin, blue eyes, and red or blonde hair are at high risk for developing sunburn after UVR exposure. People with certain genetic mutations, such as those with Xeroderma pigmentosum, experience severe sunburns after only light sunlight exposure.
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Products and Treatments
Broad-spectrum sunscreen (offering both UVA and UVB protection) of SPF 30 or greater can prevent sunburn when used appropriately.
Calamine lotion or moisturizers can help soothe and relieve pain. In sunburn with blisters, the area should be cleaned and covered with dressings soaked in saline or gauze with petrolatum.
- Oral nonsteroidal anti-inflammatory drugs (NSAIDs) can be taken to relieve pain and inflammation.
- People with severe sunburn may require hospitalization in order to replenish fluids and provide IV pain medications.
- Topical antibiotics, such as mupirocin or silver sulfadiazine, can be applied to sunburn induced blister to prevent infection.
Nutrition and Diet
A diet rich in beta-carotene or taking natural carotenoid supplements may help prevent or alleviate sunburn after UVR exposure.
Supplementation with omega-3 polyunsaturated fatty acids may protect against sunburn and reduce risk for skin cancer. More studies are needed to understand how omega-3 supplementation affects skin cancer risks.
In order to prevent sunburn, it is important to seek shade at all times when outdoors and to cover as much skin as possible with protective clothing, such as long sleeves and hats.
Broad-spectrum sunscreens with SPF of 30 or higher should be applied every day, and should be re-applied every two hours and after sweating.
Artificial UVR exposure through tanning beds should never be used, as they do not protect against sunburn.