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 within 3 days. 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

Avoidance: The best—and most obvious—way to prevent sun damage is to stay out of strong, direct sunlight. If sun exposure is unavoidable, the person should seek shade as soon as possible, cover up in UV-protective clothing, wear sunscreen, a hat, and UV-protective sunglasses. Many materials are capable of filtering or blocking UV radiation but many are not. Clothing, ordinary window glass, smoke, and smog filter out most of the damaging rays. However, water is not a good filter. UVA and UVB light can penetrate a foot (about 30 centimeters) 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.

Sunscreens: 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. Older sunscreens tended to filter only UVB light, but many newer sunscreens are now “full spectrum” and effectively filter UVA light as well.

Sunscreens contain substances, such as para-aminobenzoic acid (PABA) and benzophenone, which absorb UV light. Because PABA does not immediately bind strongly to the skin, sunscreens containing PABA must be applied 30 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 combination sunscreens 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 among 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. Newer-formulated sunblocks have a more pleasing thickness and color, which allow them to be combined with other traditional chemical blockers thereby providing even more sun protection to a given formulation.

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 2 and 12 provide some protection; those rated between 13 and 29 provide good protection; those rated 30 and above provide maximum protection. The SPF, however, only quantifies the protection against UVB exposure; there is no scale for UVA 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 Pain: Nonsteroidal Anti-Inflammatory Drugs) help relieve pain and inflammation. Ointments or lotions containing local anesthetics (eg, benzocaine) temporarily relieve pain but should be avoided because they occasionally trigger an allergic reaction. 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 and do not need to be popped and drained. 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.

Are Tans Healthy? In a word—no. Although a suntan is often considered an emblem of good health and of an active, athletic life, tanning for its own sake has no health benefit and is actually a health hazard. Any exposure to ultraviolet (UV) A or UVB light can alter or damage the skin. Long-term exposure to natural sunlight causes skin damage and increases the risk of skin cancer. Exposure to the artificial sunlight used in tanning salons is harmful as well. The UVA lights used in these establishments cause the same long-term effects as exposure to UVB light, such as wrinkling and mottled pigmentation (photoaging) and skin cancer. Quite simply, there is no “safe tan.” Self-tanning, or sunless, lotions do not really tan the skin but, rather, stain it. They therefore provide a safe way to achieve a tanned look without risking dangerous exposure to UV rays. However, because they do not increase melanin production, self-tanning lotions do not offer protection from the sun. Therefore, sunscreens should still be used during exposure to sunlight. Results with the use of self-tanning lotions may vary, depending on a person's skin type, the formulation used, and the manner in which the lotion is applied.

Last full review/revision August 2007 by Robert J. MacNeal, MD