Sunscreens are products applied to the skin to protect against the harmful effects of the sun's ultraviolet (UV) rays. While everyone needs a little sunshine (15 minutes a day helps the body make vitamin D), longer exposure may cause problems from wrinkles to skin cancer. Sunscreens help protect against thesun's damaging effects--but just how much protection they provide is a matter of debate.

The sun gives off two kinds of ultraviolet radiation -- UV-A and UV-B. For many years, experts thought that only UV-B was harmful, but recent research suggests that UV-A may be just as dangerous, although its effects may take longer to show up. In particular, UV-A may have a role in causing a particularly deadly form of skin cancer called malignant melanoma, which has been on the rise in recent decades as tanning has become more popular. Over the same period, the thin layer of ozone that protects life on earth from the sun's ultraviolet (UV) radiation is being depleted. This allows more UV radiation to get through, adding to the risk of overexposure.

Most sunscreen products contain ingredients that provide adequate protectiononly against UV-B rays. Even those labeled as "broad spectrum" sunscreens mayoffer only partial protection against UV-A radiation. Those containing the ingredient avobenzone give the most protection against UV-A rays.

Some medical experts are concerned that sunscreens give people a false senseof security, allowing them to stay in the sun longer than they should. Although sunscreens protect the skin from burning, they may not protect against other kinds of damage. A number of studies suggest that people who use sunscreens may actually increase their risk of melanoma because they spend too much time in the sun. This does not mean that people should stop using sunscreens. It means that they should not rely on sunscreens alone for protection. According to the American Academy of Dermatology, sunscreens should be one part of sun protection, along with wide-brimmed hats and tightly-woven clothing that covers the arms and legs.

Many brands of sunscreens are available that contain a variety of active ingredients that work by absorbing, reflecting, or scattering some or all of thesun's rays. The U.S. Food and Drug Administration requires sunscreen productsto carry a sun protection factor (SPF) rating on their labels. This number tells how well the sunscreen protects against burning. The higher the number,the longer a person can stay in the sun without burning. Sunscreen products are sold as lotions, creams, gels, oils, sprays, sticks, and lip balms, and can be bought without a physician's prescription.

Be sure to read the instructions that come with the sunscreen. Some need to be applied as long as one or two hours before sun exposure; others should be applied 30 minutes before exposure. It should be applied liberally to all exposed parts of the skin, including the hands, feet, nose, ears, neck, scalp (ifthe hair is thin or very short), and eyelids, but avoid the eyes. A lip balmcontaining sunscreen should be used to protect the lips. Sunscreen needs tobe reapplied liberally every one or two hours, or more frequently when perspiring heavily. Sunscreen should also be reapplied after going in the water.

Sunscreen alone will not provide full protection from the sun. When possible,the body should be protected with a hat, long pants, long-sleeved shirt, andsunglasses. It's best to avoid the sun between 10 a.m. and 2 p.m. (11 a.m. to 3 p.m. Daylight Saving Time) when the sun's rays are strongest. The sun candamage the skin even on cloudy days, so sunscreen should be used every day.Be especially careful at high elevations or in areas with surfaces that reflect the sun's rays, such as sand, water, concrete, or snow.

Sunlamps, tanning beds, and tanning booths were once thought to be safer thanthe sun, because they give off primarily UV-A rays. In fact, UV-A rays causeserious skin damage and may increase the risk of melanoma, and health experts advise people not to use these tanning devices.

People with fair skin, blond, red or light brown hair, and light colored eyesare at greatest risk for developing skin cancer. Also at high risk are thosewith many large skin moles. These people should avoid exposure to the sun asmuch as possible. However, even dark skinned people may suffer skin damage from the sun and should be careful about exposure.

Sunscreens should not be used on children under 6 months because of the riskof side effects. Instead, children this young should be kept out of the sun.Children over 6 months should be protected with clothing and sunscreens of atleast SPF 15, preferably lotions. Sunscreens containing alcohol should not be used on children because they may irritate the skin.

Older people who stay out of the sun and use sunscreens may not produce enough vitamin D in their bodies. They may need to increase the vitamin D in theirdiets by including foods such as fortified milk and salmon. A health care professional can help decide if this is necessary.

Anyone who has had unusual reactions to any sunscreen ingredients in the pastshould check with a physician or pharmacist before using a sunscreen. The doctor or pharmacist should also be told about any allergies to foods, dyes, preservatives, or other substances, especially the following:

  • Artificialsweeteners
  • Anesthetics such as benzocaine, procaine, or tetracaine
  • Diabetes medicine taken by mouth
  • Hair dyes
  • Sulfa medicines
  • Water pills
  • Cinnamon flavoring

People with skin conditions or diseases should check with their doctors before using a sunscreen. This is especially true of people with conditions that get worse with exposure to light.

The most common side effects are drying or tightening of the skin. This problem doesn't need medical attention unless it doesn't improve. Other side effects are rare, but possible. If any of the following symptoms occur, check witha doctor as soon as possible:

  • Acne
  • Burning, itching, or stinging
  • Redness or swelling
  • Rash (with or without blisters) that oozes and crusts
  • Pain
  • Pus in hair follicles.

Anyone who uses a prescription or nonprescription drug that is applied to theskin should check with a doctor before using a sunscreen.

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