Sunburn is an inflammation of the skin caused by overexposure to the ultraviolet (UV) rays of the sun. There are two types of ultraviolet rays, UVA and UVB. UVA rays penetrate the skin more deeply than UVB rays, and can cause melanoma in susceptible people. UVB rays, on the other hand, cause sunburn and wrinkling.
Skin cancer from sun overexposure is a serious health problem in the United States, affecting almost a million Americans each year. One out of 87 will develop malignant melanoma, the most serious type of skin cancer, and 7,300 of them will die each year.
Fair-skinned people are most susceptible to sunburn, because their skin produces only small amounts of the protective pigment called melanin. People trying to get a tan too quickly in strong sunlight are also more vulnerable to sunburn.
Repeated sun overexposure and burning not only cause cancer; it also can prematurely age the skin, causing a yellow, wrinkled appearance.
The ultraviolet rays in sunlight destroy cells in the outer layer of the skin, damaging tiny blood vessels underneath. Once the skin is burned, blood vessels dilate and leak fluid. Skin cells stop making protein, and the cellular DNA is damaged by the ultraviolet rays; repeated DNA damage is what can lead to cancer. As the sun burns the skin, it triggers the body's immune defenses,which identify the burned skin as "foreign." At the same time, the sun transforms a substance on the skin so that it interferes with this immune response,protecting the skin from attack by the immune system. However, this also means that any malignant cells in the skin will be able to grow freely.
Once the skin is burned, it will turn red and blister. Several days later, the dead skin cells peel off.
Aspirin or anti-inflammatory drugs can ease the pain, swelling and inflammation of sunburn. Tender skin should be protected against the sun until it has healed. In addition, sunburned skin may feel better after applications of:
- Calamine lotion
- Sunburn cream or spray
- Cool tap water compress
- Colloidal oatmeal (Aveeno) baths
- Dusting powder to reduce chafing
People who are severely sunburned should see a doctor, who may prescribe corticosteroid cream to speed healing.
Over-the-counter preparations containing aloe are an effective treatment forsunburn, easing pain and inflammation while also relieving dryness of the skin. A variety of topical herbal remedies applied as lotions, poltices, or compresses may also help relieve the effects of sunburn. Calendula (Calendulaofficinalis) is one of the most often recommended herbal treatments to ease inflammation.
Moderately burned skin should heal within a week. However, while the skin will heal after a sunburn, the risk of skin cancer increases with each exposureand subsequent burns. Even one bad burn in childhood carries an increased risk of skin cancer.
Everyone over 6 months of age on should use a water-resistant sunscreen witha sun protective factor (SPF) of at least 15. To protect the skin, individuals should apply at least one ounce of sunscreen 30 minutes before going outside, reapplying every two hours (more often after swimming). Babies should be kept completely out of the sun for the first 6 months of life, because their skin is thinner than older children and thus more susceptible to sun damage. Moreover, sunscreens have not been approved for use on infants.
In addition, people should:
- Limit sun exposure to 15 minutes the firstday, even if the weather is hazy, slowly increasing exposure daily.
- Reapply sunscreen every two hours (more often if sweating or swimming).
- Reapply waterproof sunscreen after swimming more than 80 minutes, after toweling off, or after perspiring heavily.
- Avoid the sun between 10 a.m. and 3 p.m.
- Use waterproof sunscreen on legs and feet, since the suncan burn even through water.
- Wear an opaque shirt in water, becausereflected rays are intensified.
If using a sunscreen under SPF 15, simply applying more of the same SPF won'tprolong allowed time in the sun. Instead, patients should use a higher SPF in order to lengthen exposure safely. A billed cap protects 70% of the face; awide-brimmed hat is better. People at very high risk for skin cancer can wear clothing that blocks almost all UV rays, but most people can simply wear white cotton summer-weight clothing with a tight weave.