Sunscreen by Paula Zollner, MD

Sunburn

By Paula Zollner, MD

July 2011

Sunburn occurs when the skin becomes inflamed from excessive exposure to invisible light known as ultraviolet radiation (UVR).  Avoid sunburn because it can cause skin damage that accumulates with time and contributes to the later development of skin cancer.  Skin cancer is the most common form of cancer in the U.S.

What happens during sunburn?  First, blood vessels in the skin dilate.  Then within an hour a cascade of inflammatory events ensue. In three to four hours the “erythema” or redness of sunburn is seen.  It peaks in 24 hours. 

Tanning, in contrast to sunburn, occurs when the exposure of the skin to UVR is less intense and of shorter duration.  In tanning there is an increased production of melanin pigment in the skin.  Tanning protects somewhat against further UVR damage. 

Each year about 30% of adults and 70% of adolescents and children report having a sunburn. 

People with lighter skin, hair and eyes are not surprisingly affected more frequently by sunburn.  Skin types are classified into “Fitzpatrick Types” www.nature.com/jid/journal/v122/n2/fig_tab/5602158t1.html .  Be aware of the certain classes of medication that can make a person more susceptible to sunburn.  These medications include NSAIDs  such as ibuprofen, certain antibiotics such as cipro and tetracycline, psoralens, and other medications such as Lasix, and Compazine.   Heavy alcohol consumption is well known to increase the risk of sunburn. 

Why do we worry about sunburn when uncomplicated cases usually resolve seemingly without significant consequence?  It may take 4 – 7 days for the redness to disappear and there may be scaling and peeling of skin, but the skin heals. It is the lifetime of sunburns and frequent sunburns that lead to increased skin cancer risk (premalignant lesions such as solar keratoses, basal cell and squamous cell carcinoma and melanoma) and early appearance of wrinkles and discolored skin with aging.  UV damage also increases ones risk of developing visual damage with cataracts (eye lens becomes cloudy). 

When should one seek help?  A particularly severe sunburn can cause much pain, blistering, fever, chills, nausea, vomiting, headache, blurry vision, confusion and fainting.  At this stage one is experiencing heat stroke or heat exhaustion.  Proceed to the local emergency room immediately. 

 The healthiest approach is to prevent sunburn in the first place!  Avoid UVR between the hours of 10:00 AM and 4:00 PM; cloudy days are not necessarily an exception as UVB may pass through the clouds.  Use sunscreen regularly and properly; apply it 30 minutes before exposure, especially for young children.  Sunscreen must be reapplied every 2 – 3 hours or after swimming, sweating or toweling off.  Most people don’t apply enough sunscreen.  The average adult size body needs 30 - 35 ml to be applied for the labeled SPF to be achieved.  The American Academy of Dermatology recommends a sunscreen SPF of 30 or higher. If there is no expiration date on your sunscreen bottle, get rid of it after three years.

Hats, sunglasses and loose fitting clothing with long sleeves and pants help protect against UVR.  Some specialized protective clothing is generally available.  There really is no place for tanning beds or salons; please instruct your kids to avoid them. Studies show a 75% increase in the risk for melanoma in those younger than 35 years who use tanning devices. 

For babies younger than six months, the American Academy of Pediatrics recommends the avoidance of sun exposure.  Sunscreen may be applied to exposed areas such as face, back of hands, lower legs, feet, when adequate clothing and shade is not available.

Sunscreen products contain UVA blockers such as avobenzene, drometrizole, trisiloxene and terephthalylidene and UVB blockers such as cinnamates and salicylates.  The UVB blockers such as PABA and PABA esters have fallen out of favor due to high rates of contact dermatitis and clothing staining.  Physical barriers that may be in sunscreen products include zinc oxide and titanium dioxide.  Check the ingredient label on your product bottle.   

Some studies show that oral or topical antioxidants such as the vitamins A, C, and E and green tea polyphenols give some protection against sunburn. 

If sunburn does occur the symptoms can be managed.  Stay out of the sun until pain goes away.  Ibuprofen or acetaminophens help to relieve some of the discomfort.  Use of cool compresses, low potency topical corticosteroid, aloe-based lotions or sprays and numbing medication such as Solarcaine are also helpful.  Oral diphenhydramine (Benadryl) is useful to calm the itch associated with healing sunburn. 

A few more miscellaneous facts:

-          UVR is transmitted more easily through wet clothing.

-          Snow and ice cause significantly more environmental reflection of UVR (80%) than sand (15%).

-          Moist skin is more susceptible to UVR induced erythema than dry.

-          UVB is more effective at inducing erythema than UVA, but UVA comprises the majority (95 – 98%) of the UVR reaching the earth’s surface and so accounts for a significant percent of the long term effects of UVR. 

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