Everything You Need To Know About Sunscreen

Back in the day, sunscreen was simply a summertime accessory — something you bought in preparation for your big Caribbean vacation or tossed into your bag before a full day at the lake. But today, the message from dermatologists is clear: sunscreen should be part of our daily skincare routine, even if we're just running a few quick errands on a cloudy day. Sunscreen blocks the ultraviolet radiation from the sun that causes sunburns, skin aging, and skin cancer. In fact, according to the Skin Cancer Foundation, daily use of sunscreen reduces the risk of developing certain types of skin cancer by 50% and reduces the signs of skin aging by 24%.

Despite the proven aesthetic and health benefits of wearing sunscreen, many Americans don't use it regularly. Only about 16% of women and 6% of men wear sunscreen on a daily basis, while 67% of women and 62% of men use it if they plan to be out in the sun for an extended period of time. (Interestingly, men are slightly better when it comes to remembering to reapply their sunscreen.) A whopping 46% of Americans never wear sunscreen. The most commonly cited reasons include not believing they're exposed to enough UV rays to warrant it, not burning easily, not liking how it feels on their skin, and simply forgetting (via Realself). Whether you use it daily or haven't touched a bottle of the stuff in years, here's everything you need to know about this important but oft-misunderstood product.

Why you need sunscreen

While basking in the sunshine may leave you feeling (quite literally) all warm and fuzzy, exposure to the sun's rays also carries significant risks. The one that probably springs to mind first is sunburns. A sunburn is an inflammatory reaction to damage in the skin's outermost layers caused by UV light (via the Skin Cancer Foundation). While most people think of the pain and peeling skin a sunburn causes as a minor albeit uncomfortable short-term annoyance, sunburns can have significant long-term consequences, especially when they happen repeatedly or during childhood. Five or more sunburns during your lifetime more than doubles your risk of melanoma, the most dangerous form of skin cancer. Even a single blistering sunburn in childhood or adolescence also more than doubles your melanoma risk.

Skin cancer will affect one in five Americans, and is the most commonly diagnosed group of cancers (per the Environmental Protection Agency). Unprotected exposure to UV radiation from the sun is the biggest (and most preventable) risk factor for skin cancer. The two most common forms of skin cancer are basal cell carcinoma and squamous cell carcinoma. Although generally not deadly, these cancers can cause disfigurement and serious health problems. Melanoma accounts for only about 3% of skin cancer cases, but causes 75% of skin cancer deaths. One American dies from skin cancer every hour. Unprotected sun exposure also damages the skin on a cellular level, causing signs of premature aging such as actinic keratoses (sunspots), wrinkles, and thickening.

UVA vs UVB radiation

The damage the sun does to our skin is the result of the ultraviolet (UV) radiation it produces (via the Skin Cancer Foundation). There are two types of UV radiation: UVA and UVB. UVA rays have a longer wavelength than UVB rays, and account for 95% of the UV radiation that reaches the Earth. UVA can penetrate clouds and window glass, and UVA levels remain constant during daylight hours throughout the year. As a result of these factors, we get exposed to a lot of UVA. 

UVA rays are less intense than UVB rays, but penetrate the skin more deeply. They trigger tanning and are closely associated with skin aging. UVB rays also contribute to tanning and sunburns, but are more closely linked to skin cancer risk. UVB intensity fluctuates and is highest from late morning to mid-afternoon from spring to fall. Fortunately, UVB rays can be filtered and don't penetrate glass.

For many years, UVA rays were considered harmless and sunscreen focused only on blocking UVB radiation. However, as an increasing body of research revealed the long-term dangers that UVA rays posed, manufacturers began making sunscreens that combatted both UVA and UVB. These sunscreens are labeled "broad spectrum" (via the Skin Cancer Foundation). But it wasn't until 2011 that the Food and Drug Administration (FDA) issued standards for UVA protection in broad-spectrum sunscreen. When shopping for sunscreen, always look for those labeled "broad spectrum" to give your skin the most thorough protection.

Sunscreen isn't the best or only form of sun protection

While sunscreen can be incredibly helpful, it shouldn't be your first or only line of defense against UV radiation from the sun. The simplest yet most effective way to limit UV exposure is to stay in the shade when outdoors, especially between 10 a.m. and 4 p.m. when UV radiation is most intense (via the American Cancer Society). Keep the delicate skin on your scalp, ears, face, and neck out of direct sunlight by wearing a hat with a brim of at least two or three inches. 

Of course, you can't put sunscreen on your eyes, but they too need protection from the sun. While larger-framed sunglasses will protect a wider area, don't assume that the darker the glass, the greater the UV protection. UV protection comes from a chemical in or applied to the glass, not from the glass itself. Look for sunglasses that block 99% to 100% of both UVA and UVB rays. Such glasses will say "UV absorption up to 400 nm" or "meets ANSI UV requirements" on the tag.

Clothing also offers excellent protection against the sun, and the more area you can cover, the better. Clothes can't completely block all UV light, but darker, more tightly woven fabrics are better. You can also find clothing that's been treated with a protective UV coating. These items have a label listing their UV protection factor (UPF), which uses a scale of 15 to 50+.

Sunscreen comes in many forms

If you'd rather not relive your childhood memories of being slathered head to toe in thick, goopy sunscreen, you'll be happy to know that there are many delivery methods for getting sunscreen onto your skin. 

As the American Academy of Dermatology (AAD) noted, "the kind of sunscreen you use is a matter of personal choice, and may vary depending on the area of the body to be protected." For the face and dry skin, creams are ideal. Gels are best suited for areas with a lot of hair, such as the scalp or a guy's furry chest. Sticks offer precise application, so they're great around sensitive areas like the eyes. Spray sunscreens are definitely convenient, especially for parents trying to cover young children or for getting your own back, but it can be trickier to ensure you've used enough. The AAD recommends rubbing spray sunscreen in with your hands after applying to ensure even coverage. It's also important to note that current Food and Drug Administration (FDA) regulations on testing and standardization don't yet apply to sunscreen sprays.

When it comes to protecting your lips from the sun, rather than use regular sunscreen, opt for one specifically formulated for the lips or a lip balm that offers at least SPF 15 protection (via Good Housekeeping). The lower lip in particular is a prime spot for skin cancer, so don't forget to protect your pucker.

What SPF actually means

Everyone knows sunscreen comes with an SPF (sun protection factor) rating, but there's a lot of confusion about what that number means. Many people mistakenly believe that a sunscreen's SPF denotes how much longer they can stay in the sun before burning. (For instance, if you normally burn after an hour, SPF 15 would protect you for 15 hours.) But considering there are many factors that influence UV exposure besides time in the sun (including intensity of the rays, skin type, and amount of sunscreen applied), there's no way an SPF rating could guarantee a certain amount of extra sun time for everyone (via the FDA).

In actuality, SPF refers to the percentage of UVB radiation blocked. SPF 15 blocks 93%, SPF 30 blocks 97%, SPF 50 blocks 98%, and SPF 100 blocks 99% (per UT News). So SPF 100 doesn't provide substantially more protection than SPF 30. However, if you don't apply it properly, a higher SPF may end up having the effectiveness of a lower SPF. If you're not the most thorough when it comes to application, you may want to opt for a higher SPF so that your skin is adequately protected. Dermatologists recommend using a sunscreen with an SPF of 30 or more (via the American Academy of Dermatology). It's important to remember that higher SPF sunscreen lasts the same amount of time as lower SPF sunscreen — you don't get additional time in the sun without having to reapply.

Chemical sunscreen

There are two broad categories of sunscreen: chemical and physical barrier or mineral (via Everyday Health). After you apply them, chemical sunscreens are absorbed into the skin. When UV light penetrates the skin, it reacts with the active ingredients in the sunscreen, which convert the UV radiation to heat. The heat is then dissipated from the skin in the same way as body heat. Commonly used substances in chemical sunscreen include avobenzone, homosalate, octisalate, octocrylene, oxybenzone, and octinoxate. Chemical sunscreens are easier to apply and tend to last longer than physical barrier sunscreen. They also feel lighter and don't change how the skin looks.

However, chemical sunscreens can trigger allergic reactions in some people. They can also worsen common skin conditions such as rosacea (red patches and small bumps generally seen on the cheeks, nose, and forehead) and melasma (brown patches on the face, neck, and arms). Many consumers and some studies have also raised concerns about the safety of the ingredients in chemical sunscreen, and the FDA has called for additional research. In addition, chemical sunscreen ingredients such as oxybenzone can cause environmental damage, including coral reef bleaching, when slathered-up individuals go swimming in the ocean. In fact, some tourist destinations such as Hawaii have banned the use of oxybenzone.

Physical barrier sunscreen

The second general category of sunscreen is physical barrier or mineral sunscreens. These products use tiny particles of zinc oxide and/or titanium dioxide, which sit on top of the skin and physically prevent UV rays from penetrating (via Everyday Health). Mineral sunscreens are ideal for children and those with sensitive skin. 

Both zinc oxide and titanium dioxide are classified by the FDA as generally recognized as safe (GRAS), while the jury's still out on some ingredients in chemical sunscreen. This makes physical barrier sunscreen a great choice for anyone with concerns about the safety of chemical sunscreens. Unlike chemical sunscreen, physical barrier sunscreen begins working immediately (although it's still good practice to apply it before actually going out in the sun to minimize exposure). On the flipside, mineral sunscreen is thicker and harder to apply, can leave a white film on the skin, may contribute to acne breakouts in susceptible individuals, and needs to be reapplied more frequently.

When it comes to effectiveness, zinc oxide has a slight edge over titanium dioxide because in addition to blocking short-wave UVA waves and UVB rays (which titanium dioxide can also block), zinc oxide can also block long-wave UVA waves (via Livestrong). This means zinc oxide provides an even wider spectrum of UV protection. Zinc oxide is also noncomedogenic, meaning it won't clog pores and cause breakouts. Moreover, zinc oxide sunscreen may provide some degree of protection against disease-causing microbes on the skin as well.

Applying (and reapplying) sunscreen

The best sunscreen in the world won't do you much good if you apply it incorrectly. According to the AAD, chemical sunscreen should be applied approximately 15 minutes before going out in the sun to give your skin enough time to absorb it. Adults need about an ounce (enough to fill a shot glass) to adequately cover their entire body. 

Sunscreen should be thoroughly massed into the skin. Be sure to get any area not covered by clothing, including commonly missed areas like the ears and the tops of the feet. For those with thinning hair (or no hair), apply sunscreen to the scalp, or better yet, wear a hat. For adequate back coverage, use a spray sunscreen or have a friend or family member (or perhaps your crush?) do the honors. Sunscreen should be applied every two hours or immediately after swimming or heavy sweating.

Speaking of swimming and sweating, it's important to know that truly waterproof or sweatproof sunscreen doesn't exist (via Allure). In the past, sunscreen manufacturers could use these terms on their labels, but beginning in 2012, the FDA began requiring the use of the terms "water-resistant" and "sweat-resistant." These sunscreens won't buy you any extra time before you need to reapply.

What about sunscreen mixed with other products?

Because awareness has grown about the importance of daily sunscreen use, manufacturers have begun adding sunscreen to other skincare products, including moisturizers and makeup. But in an interview with Good Housekeeping, dermatologist Dr. Dendy Engelman cautioned that sunscreen-laden moisturizers are sufficient only if you'll just be spending a few minutes here and there in the sun throughout the day. If you'll be outdoors for any longer than that, you need the real deal. 

The same goes for foundation or primer that has an SPF: it's sufficient for days spent almost entirely out of the sun, but isn't a substitute for actual facial sunscreen. It's also important to note that SPF isn't cumulative, so if your primer and your foundation each have an SPF of 15, that's not the same as SPF 30. Because chemical sunscreen needs to absorb into the skin, it should go under your makeup. Physical barrier sunscreen, on the other hand, can be applied on top of makeup (via Everyday Health), although the white film it leaves won't be doing your look any favors.

Some sunscreens may also include insect repellent such as DEET. The AAD recommends "purchasing and using these products separately — sunscreen needs to be applied generously and often, whereas insect repellant should be used sparingly and much less frequently."

People of color need sunscreen, too

There's a pervasive belief that people with darker skin don't need sunscreen because they rarely, if ever, burn. This harmful myth stems from the medical profession itself, which has historically provided subpar care to people of color (POC). Even today, many health care providers believe that darker skin is "immune" to skin cancer, and so are less likely to recognize sun exposure-related skin conditions on darker skin or recommend sunscreen use to POC. 

While it's true that overall skin cancer rates are lower in the Black community, the fact that it's not a concern on many patients' or providers' radars, combined with generally poor treatment of POC in the healthcare system, means that when skin cancer does occur, it's much more likely to be diagnosed at an advanced stage. Black individuals are four times more likely to be diagnosed with advanced-stage melanoma than light-skinned individuals and are 1.5 times more likely to die of the disease. While darker skin may provide the equivalent of SPF 13 protection, experts give POC the same recommendation to wear SPF 30 sunscreen daily that they give everyone else.

Deepening the myth that POC don't need sunscreen is the fact that the marketing and packaging of sunscreen has traditionally excluded darker-skinned individuals. Recently, however, brands have begun designing and advertising sunscreens with POC in mind. In addition to more inclusive packaging, some sunscreens targeted at POC use formulas that prevent ashy tones when applied to darker skin (via Healthline).

Babies and sunscreen

Getting too much sun exposure is risky for anyone, especially for babies. As the Skin Cancer Foundation explained, "in their first few months, babies are much more sensitive to sun exposure than adults and older children. Their skin contains little melanin, the pigment that ... provides some sun protection." 

However, experts recommend avoiding sunscreen on a baby's sensitive skin until they're at least six months old. Until then, it's best to rely on other methods of sun protection, including shade and clothing. Once a baby is old enough for sunscreen, opt for the physical barrier type that contain either zinc oxide or titanium dioxide, since these are better suited to sensitive skin. Even so, it's best to test out a new sunscreen on a small area (such as the inside of the baby's wrist) before using it all over. Just as for adults, babies should wear SPF 30 or higher.

If a baby or young child does get a sunburn, it can usually be treated at home using the same methods you'd use to treat your own sunburn. But in some cases, infant sunburn can become a medical emergency, because it's much easier for tiny bodies to become dehydrated from damaged skin (which normally keeps moisture from leaving the body). A sunburn that blisters or the presence of fever, chills, vomiting, confusion, or lethargy after a sunburn are all red flags to keep an eye out for (via Healthline).

Sunscreen storage and expiration

According to the Mayo Clinic, all sunscreens are required by the Food and Drug Administration (FDA) to maintain their original strength for three years. Some manufacturers add an expiration date indicating when this three-year period is up. If you've bought a bottle that doesn't include an expiration date, write the purchase date on the bottle so you'll know when to toss it. And if you're using sunscreen as frequently and thoroughly as experts recommend, there's no reason you shouldn't be able to get through even a Costco-size bottle of sunscreen in three years.

If you do need to throw out unused chemical sunscreen, don't pour it down the drain, as it will eventually end up in our waterways and could cause environmental damage such as coral reef bleaching. It's better to throw the unused sunscreen into the trash, although depending on the type of landfill it ends up in, this isn't a perfect solution either (via Real Simple). Be sure to recycle the container the sunscreen came in if possible. 

Ironically, when it comes to storing sunscreen, you want to keep it out of direct sun and heat. For instance, don't store sunscreen in your car during the summer. It's also best to avoid storing it in humid areas like your bathroom. Storing in non-ideal conditions can reduce the product's effectiveness.

Sunscreen safety concerns

As the AAD explained, sunscreen is technically classified as an over-the-counter (OTC) drug in the United States. This means that the FDA is in charge of regulating and monitoring sunscreen. If sunscreen includes ingredients that are classified as generally recognized as safe and effective (GRASE), then those sunscreens can be made without having to go through the FDA approval process. 

The two ingredients found in physical barrier sunscreen, titanium dioxide and zinc oxide, have GRASE status. The 12 possible ingredients used in chemical sunscreen, however, do not. These 12 ingredients are ensulizole, octisalate, homosalate, octocrylene, octinoxate, oxybenzone, avobenzone, Cinoxate, dioxybenzone, meradimate, padimate O, and sulisobenzone. That said, the latter five are not commonly used in sunscreens manufactured in the United States.

Just because these 12 ingredients don't have GRASE status doesn't necessarily mean they're unsafe. It simply means that the FDA hasn't received and reviewed enough research data to decide whether they can be classified as GRASE and can be manufactured outside of the FDA's approval process. The FDA must determine how much of the active ingredient is absorbed into the skin and, once absorbed, whether that ingredient can have any negative impacts on the skin or body. It's important to note that environmental concerns (such as oxybenzone's effects on coral reefs) don't factor into the FDA's consideration of GRASE status. If you have concerns about the safety of sunscreen ingredients, it's best to stick with physical barrier options.

Sunscreen and vitamin D

There is, however, a dark side (pun intended) to using sunscreen every day: it may negatively impact your body's ability to make vitamin D

Although vitamin D can be found in a few foods and as a dietary supplement, sunlight is the primary way humans have met their vitamin D needs throughout history. When UVB penetrate the skin, they trigger a chemical reaction with cholesterol that produces vitamin D (via the National Institutes of Health). Vitamin D is best known for its essential role in bone health, but it also has powerful anti-inflammatory properties, and is important for the functioning of the immune system and cell growth. Healthy levels of vitamin D are associated with reduced risk for cancer and depression. On the other hand, deficiency can lead to the bone disease rickets, as well as increased risk for heart disease, diabetes, autoimmune conditions, and dementia. According to a study published in the journal Cureus in 2018, almost 40% of American adults are vitamin D deficient.

Even without sunscreen, dark-skinned individuals produce little or no vitamin D from sun exposure, and even light-skinned people living in temperate climates don't get enough between November and March. Religiously wearing sunscreen as dermatologists advise blocks the UVB rays you need and adds another hurdle to getting enough vitamin D (via Harvard Magazine). To protect both your skin and your general health, be sure to wear sunscreen and get enough vitamin D from food or supplements.