Section 18. Skin Disorders

Chapter 214. Sunlight and Skin Damage

Topics: Introduction | Sunburn | Skin Photosensitivity Reactions

Sunburn

Sunburn results from a brief (acute) overexposure to ultraviolet (UV) light. The amount of sun exposure required to produce a burn varies with each person's pigmentation and ability to produce more melanin.

Sunburn results in painful reddened skin. Severe sunburn may produce swelling and blisters. Symptoms may begin as soon as 1 hour after exposure and typically reach their peak after 1 day. Some severely sunburned people develop a fever, chills, and weakness and on rare occasions even may go into shock (characterized by very low blood pressure, fainting, and profound weakness). Several days after a sunburn, people with naturally fair skin may have peeling in the burned area, usually accompanied by itching. These peeled areas are even more sensitive to sunburn for several weeks. People who have had severe sunburns when young are at greater risk of skin cancer in later years even if they have not had long-term sun exposure.

Prevention

The best--and most obvious--way to prevent sun damage is to stay out of strong, direct sunlight. If sun exposure is necessary, the person should get out of the sun quickly at the first sign of tingling or redness. Clothing and ordinary window glass filter out most of the damaging rays. Water is not a good filter: UVA and UVB light can penetrate a foot of clear water. Clouds and fog are also not good filters of UV light; a person can get sunburned on a cloudy or foggy day. Snow, water, and sand reflect sunlight, magnifying the amount of UV light that reaches the skin. People also burn more quickly at high altitudes, where the thin air allows more burning UV light to reach the skin.

Before exposure to strong direct sunlight, a person should apply a sunscreen, an ointment or cream containing chemicals that protect the skin by filtering out UV light. Most sunscreens tend to filter only UVB light, although some newer sunscreens are somewhat effective at filtering UVA light as well.

Sunscreens contain substances, such as para-aminobenzoic acid (PABA) and benzophenone, that absorb UV light. Because PABA does not immediately bind strongly to the skin, sunscreens containing PABA must be applied 30 to 45 minutes before going out in the sun or into the water. PABA may irritate the skin or cause an allergic reaction in some people. Many sunscreens contain both PABA and benzophenone or other chemicals; these combinations provide protection from a broader range of UV light. Many sunscreens claim to be either waterproof or water-resistant, but most of these nonetheless require more frequent application in people who are swimming or sweating.

Other sunscreens, called sunblocks, contain physical barriers such as zinc oxide or titanium dioxide; these thick, white ointments block almost all sunlight from the skin and can be used on small, sensitive areas, such as the nose and lips. Some cosmetics contain zinc oxide or titanium dioxide.

In the United States, sunscreens are rated by their sun protection factor (SPF) number--the higher the SPF number, the greater the protection. Sunscreens rated between 0 and 12 provide minimum protection; those rated between 13 and 29 provide moderate protection; those rated 30 and above provide maximum protection.

Treatment

Cold tap water compresses can soothe raw, hot areas, as can skin moisturizers without anesthetics or perfumes that might irritate or sensitize the skin. Nonsteroidal anti-inflammatory drugs (NSAIDs) (see Section 6, Chapter 78) help relieve pain and inflammation. Corticosteroid tablets also may help relieve the inflammation but are used only for the most serious burns. Specific antibiotic burn creams are required only for severe blistering. Most sunburn blisters break on their own: they do not need to be popped and drained unless they are still intact after 3 or 4 days. Sunburned skin rarely becomes infected, but if an infection develops, healing may be delayed. A doctor can determine the severity of an infection and prescribe antibiotics if necessary.

Sunburned skin begins healing by itself within several days, but complete healing may take weeks. After burned skin peels, the newly exposed layers are thin and initially very sensitive to sunlight and must be protected for several weeks.

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