Sunscreen is a topical (applied to skin surface) product used to protect the skin from exposure to the sun’s ultraviolet (UV) radiation. It is available in a number of forms including lotions, gels, ointments, creams, wax sticks and sprays.

There are three forms of ultraviolet rays – ultraviolet A (UVA), ultraviolet B (UVB) and ultraviolet C (UVC). UVB rays are short wavelengths of UV light that reach the epidermis (the outer layer of skin). UVA rays are longer wavelengths of UV light that penetrate the dermis (the second layer of skin).

Exposure to the sun’s UVA and UVB rays can lead to sunburn, skin cancer (melanoma and nonmelanoma), premature aging of the skin and a number of other complications.

People do not need to protect themselves from UVC rays because they are completely absorbed by the ozone layer (the protective layer in the earth’s atmosphere) and never reach the surface of the earth.

Chemical sunscreen and physical sunscreen are the two main types of sunscreen. Chemical sunscreens absorb UV rays whereas physical sunscreens absorb, block, reflect or scatter the sun’s UV rays away from the skin.

Although some people burn more easily than others, everyone should use sunscreen any time they are going to be exposed to the sun for 10 minutes or longer. It should be applied to dry skin about 20 to 30 minutes before heading outdoors.

Enough sunscreen should be used to completely cover all areas of exposed skin, including the eyelids, nose, ears, neck, hands and feet. It is also important for people to frequently reapply their sunscreen because it can be washed off, rubbed off or sweat off. In general, sunscreen should be reapplied at least every two hours. Sunscreens labeled as waterproof or water-resistant also require frequent reapplication. All forms of sunscreen, including those labeled as waterproof, should be reapplied immediately after getting out of water.  

The American Academy of Dermatology (AAD) recommends that all people, regardless of their skin color or type, use a broad-spectrum sunscreen (protects against UVA and UVB rays) with a sun protection factor (SPF) of at least 15. SPF is a number assigned to sunscreen to indicate the product’s ability to protect from UV rays. The higher a sunscreen’s SPF, the greater protection it provides. The AAD also suggests the product be used year-round, regardless of season or weather.

Sunscreen does not provide complete protection from the sun’s harmful UV rays. When used properly, however, it does greatly reduce the effects.

Sunscreen is a product used to protect the skin against the harmful effects of ultraviolet (UV) radiation. Exposure to the sun can lead to a number of complications including sunburn, skin cancer (melanoma and nonmelanoma), eye problems, a weakened immune system and premature aging of the skin.

There are two main types of sunscreen – chemical and physical. Chemical sunscreens absorb UV rays whereas physical sunscreens absorb, block, reflect or scatter the sun’s UV rays away from the skin. Chemical sunscreens are regulated by the U.S. Food and Drug Administration (FDA) as over-the-counter (OTC) drugs.

Because current sunscreens have the ability to absorb UV rays, as well as deflect them, the term “sunblock” is no longer used. There are also a number of sunscreen-containing cosmetics and lip balms available. Cosmetics that contain the same chemicals as sunscreens and claim to offer sun-protection are regulated by the FDA as both OTC drugs and cosmetics.  

Although some people sunburn more easily than others, everyone should use sunscreen, regardless of skin type or color. Sunscreen should be applied any day a person is going to be exposed to the sun for 10 minutes or longer, especially between the hours of 10:00 a.m. and 4:00 p.m. when the rays of the sun are the strongest.

Sunscreen should be applied year-round, not just during the summer. UV rays can damage the skin during any season or temperature. Even on cloudy or hazy days the sun can cause damage. According to the American Academy of Dermatology (AAD), 80 percent of the sun’s UV rays pass through the clouds. The rays can also reflect off of surfaces such as water, sand, snow and concrete. The AAD estimates that the sun’s reflective powers are approximately 17 percent greater on sand and 80 percent on snow.

Sunscreen alone does not provide complete protection against UV rays. It is only one component of a total program to reduce the harmful effects of sun exposure on the skin. For instance, sunscreen cannot protect the eyes from ultraviolet radiation, which can burn the cornea of the eye and increase the risk of developing a cataract. Therefore, it is important to also wear protective eyewear when outdoors.

Exposing the skin to the sun helps the body produce vitamin D. However, experts urge people to wear sunscreen and seek vitamin D through multivitamins and diet (e.g., vitamin D-fortified milk) instead. 

Sunscreen is available in a number of forms including lotions, gels, ointments, creams, wax sticks and sprays. In addition, there are also a number of specialized sunscreens made for certain purposes, such as for use on sensitive skin or babies. The exact type of sunscreen a person uses is a matter of personal preference.

Sunscreens should provide broad-spectrum protection. This means protection against the full spectrum of ultraviolet (UV) radiation. Sunlight contains ultraviolet A (UVA) and ultraviolet B (UVB), which can damage the body's tissues in excessive amounts. UVB rays are the primary cause of sunburn and skin cancer. 

The American Academy of Dermatology (AAD) recommends the use of sunscreen that blocks both UVA and UVB rays. In order to determine which types of sunscreen offer this type of protection, people are encouraged to read product labels. Ingredients that extend coverage beyond the UVB range and into the UVA range include: benzophenones (oxybenzone), cinnamates (octylmethyl cinnamate and cinoxate), sulisobenzone, salicylates, titanium dioxide, zinc oxide, helioplex, mexoryl and avobenzone (Parsol 1789). Some dermatologists recommend products containing the physical blocking agents titanium dioxide, zinc oxide, helioplex or mexoryl, which offer the most broad spectrum coverage to block both UVA and UVB rays. 

Sun protection factor (SPF) should also be considered. Sunscreens are classified by the strength of their SPF, which indicate the product’s ability to protect from UV rays. SPF can range from as low as two to greater than 60. The higher a sunscreen’s SPF, the more UVB rays are deflected. According to the AAD, examples of a sunscreen’s ability to deflect UVB rays include:

Currently, the SPF number on sunscreen only indicates the product’s ability to screen UVB rays because the U.S. Food and Drug Administration (FDA) has not yet approved a rating system for UVA protection.  However, in general a higher SPF sunscreen provides better UVA protection. 

SPF rating is calculated by comparing the length of time it takes for unprotected skin to turn red versus protected skin. For instance, a light-skinned person may burn after 10 minutes of unprotected sun exposure. Protected by sunscreen with an SPF of two, the same person would burn in 20 minutes.

The higher the SPF number, the longer a sunscreen will offer protection. A sunscreen rated SPF 15 would provide the same fair-skinned person with protection for 15 times longer, or 150 minutes. By comparison, a typical white t-shirt has an SPF of three. Heavier clothing typically offers an SPF of six. 

The AAD recommends that people use sunscreen with an SPF of 15 or higher. People who are very sensitive to the sun may benefit from using products with higher SPF ratings.

In addition, the AAD recommends sunscreens that are water-resistant or waterproof because they are not as easily removed by sweating or swimming.

Age is another factor to consider when choosing a sunscreen. Because the safety of sunscreen use on infants younger than 6 months has not been established, parents should discuss sunscreen with their pediatrician before using the product.  Children over the age of 6 months can safely use sunscreen. However, they should only use sunscreen that is especially made for children.

The characteristics of a person’s skin may also influence the type of sunscreen they choose. People who are prone to acne may benefit from a non-comedogenic formula. Usually found in the form of a gel, this type of sunscreen does not clog the pores. A water-based formula may also benefit individuals with acne, as well as those with oily skin. Those with sensitive skin may require a non-irritating sunscreen. A cream-based sunscreen is usually less irritating than sunscreen in a gel or lotion form. Creams are also a good choice for people with dry skin. People who have allergic reactions may benefit from using a chemical-free physical sunscreen that contains zinc oxide or titanium dioxide.

Sunscreen does not provide complete protection from the sun’s harmful ultraviolet (UV) radiation. When used properly, however, sunscreen can greatly reduce the effects of UV rays.

Sunscreen should be applied to dry skin about 20 to 30 minutes before heading outdoors. This gives the skin time to absorb the sunscreen and ensures that the sunscreen is working before skin is exposed to the sun. Depending on which form of sunscreen is being used (e.g., lotion, gel), a person may benefit from shaking the sunscreen container well before using its contents. This helps mix particles that may be clumped together in the container.  

Enough sunscreen should be used to completely cover all areas of exposed skin, including the nose, ears, neck, hands and feet. Sunscreen should also be applied to any areas of the scalp that are exposed. When using sunscreen in the form of a lotion, gel, ointment or cream, one ounce (or enough to fill a shot glass) is the recommended amount for an average-sized adult. A sunscreen–containing lip balm with a sun protection factor (SPF) of 15 or higher should also be used to cover the lips.

It is safe to apply makeup over sunscreen. Sunscreen-containing cosmetics are also available. People should avoid getting sunscreen into their eyes. Sunscreen that comes in contact with the eye often causes a temporary stinging sensation.

Sunscreen can be washed off, rubbed off or sweat off. As a result, it requires frequent reapplication. People should follow the manufacturer’s directions regarding reapplication. In general, sunscreen should be reapplied at least every two hours, regardless of the SPF. Even waterproof and water-resistant sunscreens require reapplication every two hours. It should also be reapplied immediately after getting out of water.  

Sunscreen-containing lip balm should also be reapplied at least once an hour, as well as before and after swimming, after eating and drinking and during any other activity that would remove it from the lips.

Over time, the ingredients contained in sunscreen begin to degrade. In order to ensure that sunscreen will be effective, people should keep track of when they purchase a particular product. Unless otherwise indicated by an expiration date, the U.S. Food and Drug Administration (FDA) requires that sunscreens remain at their original strength for at least three years.

Some sunscreens also contain insect repellants (e.g., DEET). The combination of these ingredients can decrease the effectiveness of the sunscreen and increase the absorption of DEET. Therefore, patients are encouraged to use separate sunscreen and insect repellant products. People who choose to use these combination products may benefit from using a product with a higher SPF and reapplying the sunscreen more often.

In rare cases, people may experience skin rash or irritation after applying sunscreen. This can result from having sensitive skin or an allergy to a fragrance, preservative or other component in the sunscreen. People should contact their physician when severe forms of these symptoms develop or fail to fade away. Patients may be able to prevent future reactions by using a different brand of sunscreen.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians. Patients may wish to ask their doctor the following sunscreen-related questions:

1. I have dark skin and I rarely burn. Do I still have to use sunscreen?
   
   
2. What type of sunscreen is best for me?
   
   
3. What is the difference between SPF 15 and SPF 30? Is SPF 30 better?
   
   
4. How often should I wear sunscreen?
   
   
5. How often should I reapply sunscreen?
   
   
6. My sunscreen is water-resistant. Do I have to reapply it after swimming?
   
   
7. Can I use sunscreen that I have left over from last summer?
   
   
8. Are my children old enough to use sunscreen?
   
   
9. I often develop a rash when I use sunscreen. What are my options?
   
   
10. Do I need to use a sunscreen-containing lip balm as well?