INTRODUCTION

Historically, a suntan was associated with good health.¹ In the 1930s and 40s, Dr. Herman Bundesen, president of the Chicago Board of Health, published articles advising mothers to place babies in direct sunlight regularly. He said “no deficiencies children develop are of greater significance than those caused by the lack of sunlight.” He went on to explain that “when [the sun] shines on a child it helps his bones and teeth to form properly [and] promotes the quality and circulation of his blood.”¹ In 1923, Gabrielle “Coco” Chanel was photographed sporting a suntan in 1923 on the French Riviera, launching suntanning as a fashion fad.¹ While not universally desired, it’s clear that tanning has integrated into Western ideas of beauty.

Although sun exposure can positively affect mood and stimulate vitamin D production, ultraviolet (UV) radiation exposure also damages deoxyribonucleic acid (DNA) and cell functions.² That damage can ultimately lead to cancer. In more recent years, as the link between sun exposure and skin cancer has been realized, health care professionals have launched campaigns to reverse the trends in tanning. In 2014, the U.S. Surgeon General issued a call to action to prevent skin cancer and address it as a major public health issue.²

Sunburns—accidental or as a result of purposeful suntanning—are a major health hazard. UV radiation is the most preventable cause of skin cancer, as experts estimate that about 90% of melanomas are caused by UV exposure.² This risk is also cumulative; risk of developing a potentially fatal melanoma doubles with a lifetime history of 5 or more sunburns.³

Skin cancer is the most commonly diagnosed cancer in the United States (U.S.).² Despite global efforts to educate the public about the dangers of the sun, people continue to overexpose themselves and develop sunburn. A National Health Interview Survey between 2005 and 2015 found that each year, more than one-third of adults in the U.S. experience at least 1 sunburn.⁴ Without additional efforts to decrease sunburn rates, skin cancer prevalence will likely continue to rise in years to come.

Getting to Know the Skin

Skin is the body’s largest organ, covering the entire external surface.⁵ It serves as a barrier against chemicals, mechanical injury, pathogens, and UV radiation and regulates temperature and water release into the environment.⁵ The 3 layers of the skin—the epidermis, dermis, and hypodermis—vary in structure and function.

The epidermis is the outermost layer of the skin made up of 5 layers (listed from innermost to outermost)⁵:

• Stratum basale: mitotically-active stem cells that are constantly producing keratinocytes; also contains melanocytes
• Stratum spinosum: 8 to 10 cell layers of irregular, polyhedral cells with “spines” that extend outward and contact neighboring cells using adhesive proteins; also contains dendritic cells
• Stratum granulosum: 3 to 5 cell layers of diamond-shaped cells with keratohyalin granules (aggregate, crosslink, and form bundles) and lamellar granules (function as a glue to keep cells stuck together)
• Stratum lucidum: 2 to 3 cell layers; thin, clear layer consisting of eleidin (a transformation product of keratohyalin); present in thicker skin (e.g., palms and soles)
• Stratum corneum: 20 to 30 cell layers (varies most in thickness, especially callused skin); made up of keratin and horny scales (dead keratinocytes, which play a role in the first immune defense by secreting defensins)

Keratinocytes are the cell type that predominate in the epidermis, but melanocytes, Langerhans’ cells, and Merkel cells are also found in this skin layer.⁵ Keratinocytes form the epidermal water barrier by making and secreting lipids. UVB light also activates cholesterol precursors in keratinocytes to form vitamin D.⁵ Melanocytes’ primary function is to produce melanin, the product responsible for skin pigmentation.

The dermis is the middle layer of the skin connected to the epidermis at the basement membrane level. It houses the blood vessels, hair/hair follicles, muscles, sensory neurons, and sweat glands.⁵ The dermis is made up of 2 layers: papillary and reticular. The papillary layer is the upper layer (adjacent to the epidermis). It is thinner and composed of loose connective tissue. The reticular layer is deeper, thicker, and less cellular. It is comprised of dense connective tissue and bundles of collagen fibers.⁵ The hypodermis, the deepest layer of the skin, lies below the dermis and is otherwise known as the subcutaneous fascia.⁵ It contains adipose lobules and some skin appendages (e.g., blood vessels, hair follicles, sensory neurons).

MYTH 1: IT’S OKAY TO TAN AS LONG AS YOU DON’T BURN, AND THE OCCASIONAL RED OR PEELING SUNBURN IS NOT BAD FOR YOU.

Contrary to popular belief, there is no such thing as a “healthy tan.” While sun exposure does pose modest health benefits, the risk of overexposure to UV radiation usually outweighs those benefits. Health benefits of sun exposure are often associated with vitamin D production.² Vitamin D is an important component of bone health and evidence shows that it plays a role in preventing various chronic diseases (e.g., autoimmune conditions, diabetes, heart disease, hypertension, obesity). About one-quarter of the U.S. population is vitamin D deficient.²

The World Health Organization says that 5 to 15 minutes of casual sun exposure on the face, arms, and hands 2 to 3 days a week in the summer can sustain adequate vitamin D concentrations in most people.²

The amount of sun exposure needed for meaningful vitamin D production, however, is dependent upon many factors²:

• Altitude
• Amount of skin exposed to the sun
• Latitude
• Reflective surfaces (e.g., snow, water, sand)
• Skin type
• Time of day and time of year
• Weather conditions

People with dark skin may require 3 to 6 times the amount of sun exposure as those with light or fair skin.² In the winter, sun exposure does not result in meaningful vitamin D synthesis.² Individuals can maintain adequate vitamin D levels safely through dietary and supplemental sources without the risks of UV radiation. Dietary sources of vitamin D include beef liver, egg yolks, fatty fish (e.g., catfish, mackerel, salmon, sardines, tuna), ricotta cheese, some cuts of pork, and some mushrooms.² Also, some foods (e.g., milk, orange juice, yogurt) are often fortified with vitamin D.

What Happens When We Tan or Sunburn?

Sunlight comprises different types of electromagnetic radiation, including infrared, visible, and UV.² UV radiation is then categorized into 3 types (see Table 1).

UVB light stimulates melanocytes in the epidermis to secrete more melanin, which causes a suntan.^2,6 While cosmetically desirable, a suntan is nothing more than the body trying to protect itself from additional UV damage. Melanin protects the skin from further UV radiation, essentially acting as a built-in sunscreen.^5,6 Genetics determine how much melanin the skin produces, which is why some people burn while others simply tan.³ Both tan and burn, however, are signs of skin damage, and even without a burn, sun exposure increases skin cancer risk.³

Sunburn is an inflammatory reaction to UV radiation damage from sunlight, and reactions can range from mild to blistering.³ High UV radiation doses kill most of the skin cells in the outermost layer, and the remaining cells in the layer are damaged.⁶ UVA and UVB radiation both contribute to sunburn, but UVB rays are responsible for directly damaging DNA through formation of cyclobutane thymine dimers.⁷ In response to formation of these dimers, the body launches a DNA repair response.⁷ This induces cell apoptosis and prompts the release of inflammatory markers including bradykinin, prostaglandins, and reactive oxygen species.

This inflammatory reaction causes vasodilation (dilated blood vessels), edema (fluid collection), and pain, which produces the cardinal symptoms of sunburn: red, painful skin.⁷ The degree of erythema (skin redness) and pain is directly proportional to the severity of sun exposure, and it usually reaches maximum intensity between 8 and 24 hours after exposure.^7,6 Skin may be warm to the touch, swollen, or itchy, and if the burn is severe enough patients may experience nausea, fever, and chills. A deeper, partial thickness burn may also cause blisters or peeling.⁷ Blistering and peeling leave the new, very white skin underneath unprotected and even more vulnerable to UV damage.⁶ Since the inflammatory reaction occurs before erythema appears, skin redness may not be the first sign of a sunburn. It will likely feel itchy, hot, tender, and/or tight and patients may feel thirsty.

Some individuals may think they have windburn, not sunburn, as both can cause erythema.⁸ The truth is, it’s probably both. Wind is a direct irritant that causes the upper layers of the skin to slough off. As these skin cells leave, they also take sunscreen with it.⁹ This shedding leaves skin more vulnerable to UV radiation.⁸ Sun-protective clothing and reapplying sunscreen regularly are important on a windy day.

Consequences of Sunburn

The dangers of sunburn last far beyond short-term discomfort. After the redness and swelling subside, lasting damage remains. The most notable consequence of sunburn is skin cancer. In fact, it is a leading cause in the majority of basal cell and squamous cell carcinomas and melanomas, which is the deadliest form of skin cancer.³ Regardless of severity, any burn is a sign of skin injury that can ultimately lead to premature skin aging and cancer.

The degree that UV exposure increases cancer risk depends on many factors, including age, skin type, amount and type of sun protection used, and whether exposure is chronic or intermittent.² Sunburn damage is cumulative, so repeated sunburns raise the risk of melanoma significantly. Subsequent UV damage can also occur even without obvious burn symptoms.³ Research also shows that skin-damaging UV rays can alter a tumor-suppressor gene. This means injured cells have less of a chance to repair before progressing to a cancerous state. While burns of all severity are harmful, even 1 blistering sunburn in childhood or adolescence doubles the chance of melanoma in adulthood.³

Aside from skin cancer risk, UV radiation can adversely affect the skin, eyes, and immune system. Excessive UV radiation causes premature skin aging, including wrinkles, mottled pigmentation, and loss of elasticity.² The sun’s rays, in general, dry out the skin leaving it coarse and leathery.⁶ UVB rays stimulate cell proliferation on the outer layer of the skin, causing it to produce more and more cells until the epidermis thickens.⁶ UVA rays, however, penetrate deeper into skin layers to disturb connective tissue. This results in elasticity loss manifesting as wrinkles, sags, and bags. Additionally, sometimes the skin over-produces melanin in localized areas, resulting in dark patches or liver spots.⁶

Eyes take up merely 2% of the body’s surface area, but they are the only organ system that allows penetration of visible light deep into the human body.⁶ UV exposure damages eyes, affecting surface tissues and internal structures (e.g., cornea, lens).² It can also cause photokeratitis (sunburn of the eye) that leads to cornea inflammation.^2,6 Although very painful, photokeratitis is reversible and does not appear to result in long-term eye or vision damage.⁶ Wearing properly-fitting sunglasses with 100% UVA and UVB protection is the best way to protect eyes from UV damage.² Refer patients experiencing eye pain a few hours after excessive UV exposure to an eye care provider promptly.

Effects on the immune system are less well-understood, but UVB radiation seems to hinder immune system effectiveness.⁶ Research has shown that environmental UV levels can alter the distribution and activity of some cells responsible for immune responses.⁶ For example, sun exposure can precede the onset of recurrent cold sore eruptions. When affected by UV radiation, the body can no longer keep the Herpes simplex virus under control, which results in re-activation of the virus.⁶ Excessive UV exposure can also reduce effectiveness of folic acid supplements.² This is especially important for pregnant women and women of childbearing age to be aware of.

High UV radiation levels may also decrease vaccine effectiveness.⁶¹⁰ Studies on this topic are limited, but animal models indicate that memory response to an antigen presented in a vaccine is reduced by UV exposure.¹⁰ Human studies have examined vaccine effectiveness based on climate, drawing conclusions that hepatitis B, live influenza, live rubella, and poliovirus vaccines produced greater antibody responses in temperate versus tropical zones. The same effect was seen when vaccines are given in the winter versus the summer.¹⁰ There is no widely-accepted guideline for separation of UV radiation from vaccinations, and further studies are needed.

MYTH 2: YOU CAN ONLY GET A SUNBURN IF YOU’RE SITTING DIRECTLY IN THE BRIGHT SUN ON A HOT SUMMER DAY.

Sitting on a beach on a hot summer day is not the only way to get a sunburn. In fact, people can get sunburned even without going outdoors.

UV Index Scale

The U.S. National Weather Service (NWS) calculates the UV Index utilizing a computer that relates ground-level strength of solar UV radiation to forecasted stratospheric ozone concentration, forecasted cloud amounts, and ground elevation.¹¹ The National Oceanic and Atmospheric Administration operates 2 satellites that measure current total ozone amounts around the globe. Then, the NWS calculates the sun angle based on latitude, day of year, and time of day, and they use this information with ozone amounts to determine the ground level strength of UV radiation for wavelengths between 280 nm and 400 nm (the full spectrum of UVA and UVB radiation.¹¹

NWS adjusts UV Index calculations based on human skin’s sensitivity to UV radiation. Shorter wavelengths cause more skin damage than longer ones of the same intensity.¹¹ They also adjust for effects of elevation and clouds. For every kilometer elevation above sea level, UV intensity increases about 6%.¹¹ Also, clouds absorb some UV radiation, which reduces ground-level intensity.¹¹

Luckily, people do not need to calculate the UV Index themselves on a daily basis to determine sun exposure risk. Most weather apps and websites provide this information on a daily and even hourly basis. The U.S. Environmental Protection Agency (EPA) developed the UV Index scale, which helps people determine when it is safest to spend time outdoors and how much sun protection to use.² The UV Index scale indicates how to use the UV Index to help avoid harmful radiation exposure, with a lower UV Index indicating a lower risk on a scale of 0 to 11 (see Figure 1).² As UV Index increases, so does the recommended level of sun protection.¹²

In the winter, the UV Index averages 2 or below nearly everywhere in the U.S. except Florida and Hawaii, but reflective surfaces (e.g., sand, snow, water) and high altitudes can increase UV overexposure and sunburn risk.² People should utilize the UV Index in their current location along with the EPA’s scale to ensure they use adequate sun protection at any point in the day.

Figure 1. Using the UV Index Scale to Avoid Overexposure¹²

Other Places to Feel the Burn

Individuals may feel safe from sunburn in many places where they are not truly protected. One of those places is in the shade of a big, fluffy cloud. People may not realize they can still develop a sunburn on a cloudy, windy, or cool day.

A cloudy day is not adequate sun protection. Clear skies allow virtually all UV rays to pass through, while scattered clouds transmit 89%, broken clouds transmit 73%, and overcast skies transmit 31%.¹¹ People should take care to use shade materials without holes or gaps, which can allow UV radiation to penetrate them. For example, trees with denser foliage and wider canopies provide better coverage than those with sparse foliage and dappled sunlight.⁹

Many surfaces (e.g., sand, snow, water) can also reflect UV rays, making it easier to be overexposed, even while in the shade. Sand reflects 20% to 30% of UV rays, so people under an umbrella on the beach can still be burned by reflected radiation.² Water reflects 5% to 7% of UV rays too, so beachgoers and pool-dwellers should be aware they can still be burned in the ocean or another body of water.² Additionally, up to 40% of UV radiation still reaches the skin even half a meter below the water surface.⁹ This is especially important given that the cooling effect of water may mask the feeling of a sunburn.

Some manmade surfaces can also increase reflectivity, including concrete, which reflects about 14% to 15% of UV rays.² Grass, only reflects about 1% to 2% of UV radiation, so people in reliable shade cover on grassy surfaces are adequately protected.² Winter sports are also of concern with sun safety, as people may feel safer from UV radiation when it’s cold outside. Snow, however, reflects 80% to 90% of UV rays, making it entirely possible to get a sunburn on exposed skin.²

Sunburn danger is also not limited to the outdoors. Americans spend an estimated 90% of their time indoors and in their cars, and UV exposure through windows and automobile glass is possible.¹³ Home windows can transmit as much as 74.3% of UV rays, depending on the type of glass.¹³ A study evaluated UV radiation exposure in cars with open and closed windows and found that this exposure is high enough that it should be considered part of people’s lifetime UV exposure.¹⁴ Australian studies also found that people are more likely to develop skin cancers on their right side (the outward glass side for an Australian driver) than the left side of sun-exposed areas.^15,16 An additional U.S. study found a correlation between participants with more photodamage on the left side (driver side) and the amount of time spent driving.¹⁷

Factors that Increase Sunburn Risk

Many behaviors, conditions, and medications can affect the skin’s susceptibility to UV radiation and sunburn. Skincare products marketed for anti-aging and acne often increase sun sensitivity.¹⁸ Retinol—also known as vitamin A—is often touted as the “holy grail” of skincare. It promotes skin renewal and enhances collagen production, targeting fine lines, wrinkles, pore size, and uneven skin texture or tone.¹⁸ When retinol stimulates production of new skin cells, that new skin is more delicate and thinner making it more susceptible to UV radiation damage.¹⁸ Advise people using retinol products to limit them to nighttime use and to use adequate sun protection daily.

Alpha hydroxy acids (AHA; e.g., glycolic acid), commonly found in skin-brightening and acne-fighting products, chemically exfoliate the skin.¹⁸ This exfoliation makes skin more susceptible to UV damage, even up to 24 hours later. These products should always be used in conjunction with sunscreen to prevent UV radiation overexposure and skin damage. People should practice this with all forms of exfoliation, including physical exfoliation with special brushes or textured skincare products. People should avoid direct sunlight for 2 to 3 days after exfoliation and use sunscreen if exposure is unavoidable.

Another important ingredient to watch for is hydroquinone, a lightening agent that fades skin discoloration.¹⁸ This chemical disrupts the formation of excess melanin that leads to dark spots, melasma, and hyperpigmentation. Melanin, as discussed, is the skin’s natural way of protecting itself from sun damage, so halting its production makes the skin more susceptible to UV radiation and damage.¹⁸ Hydroquinone users should avoid direct sun light as much as possible.

Drug-Induced Photosensitivity

A number of medications can cause photosensitivity (see Table 2). Drugs can induce 2 types of photosensitivity reactions: phototoxicity and photoallergy.¹⁹ Reactions can be topical or systemic. Photosensitizers absorb photons from solar radiation, leading to their activation and induction of chemical reactions. This happens primarily from UVA radiation, but UVB can sometimes induce photosensitivity.¹⁹

The number of photosensitivity-inducing drugs varies depending on the source, but some associate nearly 400 drugs with these reactions.¹⁹ However, 4 drug classes are consistently implicated in all published lists of photosensitive drugs: nonsteroidal anti-inflammatory drugs (NSAIDs), antimicrobials, antihypertensives, and antineoplastic drugs.¹⁹

Phototoxic reactions are more common than photoallergic.¹⁹ They are dose-dependent with respect to the drug and the UV exposure. Skin reactions vary depending on the offending agent, but erythema is the most common clinical manifestation. It can have immediate, delayed (12 to 24 hours), or late (24 to 120 hours).¹⁹ People sometimes refer to delayed-onset erythema as “exaggerated sunburn.” Immediate reactions include burning or prickling sensations and edema. Patients may experience hyperpigmentation and telangiectasia (“spider veins”) long-term.¹⁹ Phototoxicity is non-immunological, so it can only occur in the skin areas exposed to light. Phototoxic medications generally share common features, including low molecular weight (200 to 500 Daltons).¹⁹

Photoallergic reactions occur as a result of the photosensitizer absorbing photons from UV light and converting it into a biologically-reactive molecule.¹⁹ This molecule binds to a protein in the dermis or epidermis to form a complete antigen (referred to as haptenization). This activates the immune system and incudes a cell-mediated type IV hypersensitivity reaction. Photoallergy presents as eczematous eruptions in areas of skin exposed to UV radiation. However, they lack the sharp delineation of phototoxic skin lesions and they take longer (about 24 to 72 hours) to present given the immune reaction that must take place.¹⁹ People must be exposed to the offending agent more than once before a reaction occurs. Not all drugs that induce phototoxicity also induce photoallergy. Common drugs that induce photoallergy include 5-fluorouracil, celecoxib, ketoprofen, and quinidine.²⁰

As pharmacists, a major responsibility is informing patients of potential adverse effects (including photosensitivity). Pharmacy technicians are often patients’ first point-of-contact and should recognize medications—prescription and over-the-counter (OTC)—that cause photosensitivity and promptly refer patients to the pharmacist. As noted, prevention is key when it comes to sun damage. Proactively advising patients to use adequate sun protection while using medications and products that can increase sensitivity to UV radiation is crucial.

MYTH 3: ALL SUNSCREEN IS CREATED EQUAL, AND ANY SUNSCREEN IS BETTER THAN NO SUNSCREEN.

Navigating the drugstore sunscreen shelf can be a daunting task. Pharmacists and pharmacy technicians should recognize the major differences between products to help patients select adequate and appropriate sun protection.

What’s in a Sunscreen?

Sunscreens can generally be divided into 2 major categories: chemical and physical.²¹ Some products combine both mechanisms, but for the most part, sunscreens are one or the other. Chemical sunscreens protect the skin by absorbing the sun’s rays.²¹ The most common active ingredients in these products are oxybenzone and avobenzone. Other chemical UV filters used in the U.S. include ensulizole, homosalate, octinoxate, octisalate, and octocrylene.²²

Physical sunscreens—sometimes referred to as mineral sunscreens—protect the skin by deflecting the sun’s rays.²¹ The active ingredients most commonly found in these products are titanium dioxide and/or zinc oxide.^21,22 These are inorganic mineral compounds that are largely insoluble in water and biological fluids.²² They sit on top of the skin to deflect UVB and UVA rays by reflecting and scattering UV light, depending on particle size. Zinc oxide is especially good at this, as it’s 1 of 2 sunscreen ingredients (the other being avobenzone) that can protect from UVA wavelengths longer than 360 nm.²²

People have historically used zinc oxide to treat burns and other wounds. Titanium dioxide is the most commonly used white pigment and is found in many products other than sunscreen, including toothpaste, lotion, skim milk, and cottage cheese.²² These active ingredients have been included in sunscreens since the 1980s and are unlikely to irritate the skin. They are classified as biologically inert with no significant toxicities, making them suitable for sensitive skin and children.²²

Some sunscreens tout the claim of being “water resistant.”²¹ The U.S. Food and Drug Administration (FDA) requires companies to test sunscreens before allowing them to use this designation. FDA defines the use of this term based on how long the sunscreen stays on wet skin. Sunscreens that stay effective for 40 minutes in the water can be considered “water resistant,” while products that stay effective for 80 minutes in the water can be considered “very water resistant.”²¹ Importantly, if individuals apply water resistant sunscreen and do not get wet, they still need to reapply every 2 hours. Also, no product is water- or sweat-proof, so people should always reapply them every 2 hours or after swimming or sweating.²¹

Unfortunately, some companies use advertising buzz-words to describe sunscreens that the FDA has not defined, leaving room for interpretation. The word “sports,” for example, has no meaning on sunscreen, although some companies use it to imply the product is water resistant.²¹ People should check the label further before assuming a “sports” sunscreen is water resistant. The word “baby” also has no FDA-defined meaning, but in general “baby” sunscreens contain titanium dioxide and/or zinc oxide as active ingredients.²¹ Another ill-defined designation without FDA definition is “sensitive skin.” “Sensitive skin” products can mean that the sunscreen²¹

• contains titanium dioxide and/or zinc oxide
• does not contain fragrance, oils, para-aminobenzoic acid (PABA), or chemical sunscreen active ingredients, which can irritate skin
• is hypoallergenic

The American Academy of Dermatology (AAD) recommends that consumers not use sunscreens that also contain insect repellent.²¹ While both of these are important, individuals should apply sunscreen liberally and often, while they should use insect repellent sparingly and less often. Additionally, remind patients that if they also use sunscreen, they should apply sunscreen first and insect repellent second.²⁴ It is hypothesized that sunscreen applied over insect repellent may inhibit the repellent’s evaporation, therefore lowering its ability to repel insects. 

Varying Levels of Protection

Differentiating between sun protection products requires an understanding of the difference between sun protection factor (SPF) and ultraviolet protection factor (UPF). SPF tells consumers how much UVB light a sunscreen product can filter. The minimal erythema dose (MED) is the amount of UV radiation needed to provoke erythema of the skin.²⁵ SPF is calculated as .²⁵ FDA states that “SPF is a relative measure of the amount of sunburn protection provided by sunscreens.”²⁶ It allows consumers to assume that products with higher SPF provide more protection than those with lower SPF.

There is a popular misunderstanding that SPF relates to time, rather than UV exposure.²⁶ For example, many consumers believe that if they normally get sunburned in 1 hour, then an SPF 15 sunscreen allows them to spend 15 hours in the sun (i.e., 15 times longer) without burning. Although UV exposure is related to the amount of time spent in the sun, other things (refer to UV Index Scale section above) influence the amount of UV radiation that reaches the skin. Spending 1 hour in the sun at 9:00 AM could produce the same about of UV radiation as 15 minutes at 1:00 PM, for instance.²⁶

No sunscreen blocks 100% of the sun's rays, which is why sunscreen is no longer referred to as sunblock. However, a higher SPF has been shown to protect skin better than a lower one.²¹ The AAD recommends selecting a sunscreen with an SPF rating of 30 or higher.²¹ Broad-spectrum sunscreens are those that protect users from both UVA and UVB radiation.²¹ The AAD recommends using broad-spectrum products whenever possible.

Of note, some people think that already being tan or getting a “base tan” is protective enough against UV radiation and they do not need sunscreen. This is far from the truth. A dark tan on white skin offers a sun protection factor (SPF) of about 2 to 4.⁶ It also offers no defense against long-term damage or cancer.⁶

UPF applies to sun-protective clothing, rather than sunscreen.²⁷ UPF indicates how much UV radiation (including UVA and UVB rays) a fabric allows to reach the skin.²⁷ For example, a UPF 50 fabric allows 1/50^th (2%) of the sun’s rays to penetrate, meaning it blocks 98%. The Skin Cancer Foundation requires fabric to have a UPF of at least 30 to qualify for their “Seal of Recommendation.”²⁷ They consider UPF 30 to 49 as very good protection and UPF 50 or more as excellent. A common misconception is that all clothing protects from UV radiation equally, but this is untrue. Sun safety of clothing depends on many factors²⁷:

• Color: dark or bright colors absorb UV rays rather than allowing to them to penetrate, so they offer better protection than lighter colors
• Construction: densely woven cloth (e.g., canvas, denim, synthetic fibers, wool) is more protective than sheer, thin, or loosely woven cloth; if the fabric is see-through when held to the light, UV radiation can easily penetrate and reach the skin
• Content: unbleached cotton contains natural polymers that absorb UV radiation; shiny polyesters and satin/silk can be highly protective because they reflect radiation; high-tech fabrics treated with chemical UV absorbers or dyes prevent some UV penetration
• Fit: loose-fitting clothing is preferred, as tight clothing can stretch and pull fibers apart, allowing more UV light to penetrate the material
• Coverage: the more skin covered, the better, so long-sleeved shirts and long pants or skirts are preferred
• Activity: regardless of its UPF, if clothing is stretched or wet, it will become more transparent and lose some of its protective ability

Sunscreen Formulations

Sunscreen comes in many formulations, including creams, gels, lotions, sprays, sticks, and wipes.²⁸ A good sunscreen product must coat the skin’s surface uniformly, but this can be challenging given that the skin’s topography is very uneven.²⁸ A layer of applied sunscreen is less than 0.001 inches thick, leaving much room for error and missed spots.²⁸

Skin is a series of peaks and valleys, and often excess sunscreen accumulates in the valleys, while peaks are very poorly coated. For safety reasons, the product should absorb only minimally, if at all, into the skin to prevent systemic absorption.²⁸ To cover the skin surface evenly, a good sunscreen product’s viscosity should decrease significantly during the process of spreading product on the skin.²⁸ Subsequently, the product should regain its higher viscosity quickly after application so the product stays in place and does not pool in the skin’s valleys.

Even the perfect sunscreen product must promote user adherence to be effective. For example, if an SPF 30 sunscreen feels greasy or sticky, people will tend to use less of it or not reapply it often enough to achieve the SPF 30 protection.²⁸ To promote sunscreen adherence, pharmacy teams should encourage patients to try different sunscreen products until they find one that works well for them. Use Figure 2 to help patients navigate the many available sunscreen options.

Figure 2. Relative Thickness of Sunscreen Formulations²⁸

Oil-based sunscreens tend to have a heavy, greasy skin feel and generally low actual SPF on skin because of their poor film-forming ability (i.e., oils tend to not stay in place on skin).²⁸ Ethanol/oil-based products tend to have a better feel, as ethanol evaporates quickly and reduces the amount of residual material left on the skin. They can, however, also be very drying and slightly irritating, especially to patients with existing eczemas or other skin issues.²⁸ Emulsion-based products—especially creams and lotions—are the most common sunscreen products on the market.²⁸ Lotions tend to be thinner emulsions, while creams are thicker emulsions. These products also usually have good skin feel, as they contain water as a main component which reduces the amount of residual product on skin.

Sunscreen sprays allow users to apply product to hard-to-reach areas, but some spray products still need to be rubbed into skin for uniform coverage.²⁸ Some thin oil-in-water emulsion-based sunscreens can also be formulated into mousse products. Sunscreen wipes have sunscreen formulations absorbed onto a nonwoven substrate, and these formulations must be thin to adequately absorb into/onto the wipe.²⁸ For this reason, similar thin sunscreen formulations are used for sprays and wipes. Sunscreen wipes are convenient applicators for easy coating with a uniform product film on the skin. However, they also tend to be less stable than other forms of sunscreen so active ingredients may break down faster.

Sunscreen Application

A sunscreen’s ingredients and SPF mean nothing if users apply it incorrectly. The FDA and International Organization for Standardization advise that the amount of sunscreen applied should be 2 mg/cm² to achieve the labeled SPF on the package.²⁵ The AAD says that most people require about 1 ounce (i.e., about enough to fill a shot glass) of sunscreen lotion or cream to fully cover the body.²⁹ Most people, however, only apply 25% to 50% of the recommended amount of sunscreen needed for adequate UV protection.^22,25

People should apply sunscreen at least 15 to 20 minutes before they go outdoors, not when they are already in the sun.^25,29 Chemical sunscreens take about this long to absorb and provide protection, so entering direct sunlight before 15 minutes have passed exposes unprotected skin to UV radiation.²⁹ Mineral sunscreen, on the other hand, provides immediate UV protection.²² There is no official guidance on specific application procedures for mineral-based sunscreens, but waiting 15 minutes before sun exposure allows the product to form a better protective film first.²² Some people may apply sunscreen before dressing in the morning, which is ideal. However, it is recommended that they wait at least 20 minutes after application to get dressed, as clothing could potentially strip away some of the unabsorbed sunscreen.²⁵

Individuals should apply sunscreen to all skin not covered by clothing and under clothing with low UPF protection. Focus on commonly-missed areas, including the ears, face (including eyelids), neck, and tops and bottoms of feet. People should also apply a lip balm with at least SPF 15 to protect the lips.²⁹

Reapplication is important for longevity of UV protection. People should reapply sunscreen every 2 hours and immediately after swimming or sweating, even if the product claims to be water resistant.²⁹ Parents and caregivers should not apply sunscreen to children younger than 6 months old. Instead, they should utilize clothing with UPF protection and keep them in the shade as much as possible.

Sunscreen Safety

Sunscreen products are intended to be applied to the body daily for a lifetime, making the safety of these products of the utmost importance. Of the 16 marketed sunscreen ingredients, only 2—titanium dioxide and zinc oxide—have FDA’s GRASE (generally recognized as safe and effective) rating.²² FDA considers an additional 2 ingredients—the chemical filters PABA and trolamine salicylate—unsafe for use due to safety concerns. The remaining 12 active chemical ingredients have insufficient safety data to make a positive GRASE determination.²²

Constant exposure to sunscreen chemicals raises concerns, especially given the lack of safety data for most ingredients. FDA published studies showing that avobenzone, homosalate, octinoxate, octisalate, octocrylene, and oxybenzone are all systemically absorbed into the body after only 1 use.³⁰ They also showed that these could be found on the skin and in the blood weeks after discontinued use. Many sunscreen ingredients can also be detected in breastmilk and urine samples.³⁰ Sunscreen sprays run the risk of inhalation and products applied to lips could potentially be ingested. This stresses the importance of determining if sunscreen ingredients could harm lungs or internal organs.

Based on recent research, the most worrisome ingredient in sunscreen is oxybenzone.³⁰ Oxybenzone is readily absorbed through the skin, causes allergic skin reactions, behaves as an endocrine system disruptor (i.e., affects hormone regulation and potentially fertility), and has greater potential to harm children.³⁰ These affects extend to lower adolescent male testosterone levels, negative pregnancy and birth outcomes, and increased risk of endometriosis in women.³⁰

In the past decade, FDA has worked to more tightly regulate sunscreen products as OTC products. The Sunscreen Innovation Act (SIA) in 2014 provided an alternative process for safety and efficacy review of nonprescription sunscreen active ingredients.³¹ In early 2019, FDA subsequently issued a proposed rule to update regulatory requirements for sunscreen products in the U.S.³² This rule, if adopted, would enact final monograph regulations for OTC sunscreen products, improving safety and reducing misbranding to help consumers select adequate sun protection. It proposes the following³²:

• Industry and other stakeholders provide additional safety data to make GRASE determinations or rejections for more active ingredients
• Dosage forms that are GRASE for use as sunscreens include butters, creams, gels, lotions, oils, ointments, pastes, sprays, and sticks; powders require more data; body washes, shampoos, towelettes, and wipes should be categorized as new drugs because FDA has not received enough data for inclusion
• Raise maximum proposed SPF value on sunscreen labels from SPF 50+ to 60+
• Require that sunscreens with SPF 15 or more also provide broad-spectrum protection; for broad-spectrum products, as SPF increases, the magnitude of protection against UVA radiation also increases
• Implement new sunscreen product label requirements to assist consumers in more easily identifying key information
  • List active ingredient(s) on the front of the package to bring sunscreen in line with other OTC drugs
  • Include a notification of the skin cancer/skin aging alert on the front label for sunscreens that have not been shown to help prevent skin cancer
  • Revise formats for SPF, broad spectrum and water resistance statements
• Clarify FDA expectations for testing and record keeping to ensure FDA can assess industry regulation compliance
• Products that combine sunscreens with insect repellents are not GRASE

In May 2021, an independent pharmaceutical testing company petitioned to the FDA to recall 78 different sunscreen and after-sun care products that they found to contain benzene.³³ Benzene is a known carcinogen (cancer-causing substance) and also poses other potentially serious health risks when inhaled, ingested, absorbed through skin, or has contact with skin and/or eyes. About 27% of batches the testing company examined contained detectable benzene, with some reporting as much as 3-times the FDA-accepted concentration limit of 2 ppm.³³ While FDA has not issued an official recall, these findings are public and consumers may be concerned. As of July 16, 2021, Johnson & Johnson has voluntarily recalled 5 sunscreen products in response to this report.³⁴ Direct people to Tables 2 and 3 of the testing company’s findings at https://www.valisure.com/wp-content/uploads/Valisure-Citizen-Petition-on-Benzene-in-Sunscreen-and-After-sun-Care-Products-v9.7.pdf to determine if their sun care brands contained detectable benzene levels.³³

Pharmacy teams should also remind patients that sunscreens expire.³⁴ People should discard sunscreen that is past its printed expiration date. Some products, however, do not include an expiration date. FDA requires that sunscreens maintain their original strengths for at least 3 years, so if individuals purchase sunscreen without a date, recommend that they write the date of purchase on the bottle and discard it 3 years later.³⁴ To keep sunscreen in good condition, people should avoid exposing the container to excessive heat or direct sun, as this can break down the ingredients faster. Also, they should discard the product if it has any obvious changes to color or consistency, indicating it may have gone bad.³⁴

MYTH 4: ALL SUNBURNS WILL SELF-HEAL WITHIN A FEW DAYS.

Sunburn symptoms are not immediately apparent; they usually start about 4 hours after sun exposure, worsen in 24 to 36 hours.³⁵ Mild burns typically resolve in 3 to 5 days, but severe burns can take weeks.³⁵ Pain usually worsens about 6 to 48 hours after sun exposure, and skin peeling usually occurs about 3 to 8 days after exposure.³⁵

The body’s healing rate may be genetically determined, but factors including age and overall health can also play a role.³⁶ Lifestyle factors that slow the body’s ability to heal a sunburn include smoking and chronic stress. Medical conditions that weaken the immune system (e.g., diabetes, malnutrition, obesity) can also slow the healing process. Arterial disease and poor circulation can also decrease blood flow to the burned area, lengthening the time needed to heal.³⁶

As discussed, the damage is already done when sunburn develops and cannot be reversed. Acute symptoms, however, can be uncomfortable and distressing and pharmacy teams should advise patients how to treat them appropriately.

Sunburn Treatment: Adults

Upon developing a sunburn, the first thing to do is remove the stressor by getting out of the sun (preferably indoors) as soon as possible. Next, the AAD recommends the following³⁷:

1. Take frequent cool baths or showers to relieve pain. Immediately upon exiting the bathtub or shower, gently pat dry but leave skin slightly moist.
2. Apply a moisturizer to trap the water in the skin and ease the dryness. (Pro-tip: cool off moisturizer in the fridge for added cooling effect while applying.)
3. If a particular area is especially uncomfortable, use OTC hydrocortisone cream. Pharmacy teams should remind patients to apply hydrocortisone sparingly 2 to 3 times daily and not to use occlusive dressings over it. (Of note, never use pain-relieving “-caine” products [e.g., benzocaine] to treat sunburn, as these may irritate skin or cause allergic reaction that exacerbates sunburn symptoms.)
4. Consider taking aspirin or ibuprofen to reduce swelling, redness, and discomfort only if not contraindicated (e.g., NSAID allergy, peptic ulcers, stomach bleeding).

Sunburned skin draws fluid to the surface and away from the rest of the body, which can cause dehydration.³⁷ Patients with sunburn should drink extra water and take extra care to remain hydrated. If skin blisters, this is indicative of a second-degree burn.³⁷ Advise patients to not intentionally pop these blisters, as they form to help skin heal and protect from infection. Most importantly, people who have a sunburn should take extra precaution to protect their burned skin while it heals. They should avoid the sun as much as possible, and if being outdoors is unavoidable, they should wear clothing made of tightly-woven fabrics to protect skin from further damage.³⁷ Some online resources suggest inappropriate home remedies (see Table 3) that pharmacy teams should advise people to avoid.

Individuals with sunburn should seek medical help if they have severe blistering over a large portion of the body, have a fever and chills, or feel woozy or confused.³ These can be signs of sun poisoning, a more severe form of sunburn. Speak to a medical professional if sunburn is accompanied by headache or muscle cramps. Additionally, if blisters pop and skin becomes infected, it will likely have red streaks or begin oozing pus. This should prompt a sunburned person to seek medical attention.

Sunburn Treatment: Children

Younger skin heals faster than older skin, but it is also more vulnerable to injury from UV radiation.³ If children become sunburned, their parent or caregiver should do the following³:

1. Bathe the child in clear, tepid water to cool the skin.
2. Apply light moisturizing lotion to soothe the skin, but do not rub it in.
3. Dab on plain calamine lotion if more relief is needed, but do not use one with an added antihistamine.

Caregivers should not apply alcohol to the child’s skin, as this can overcool it.³ Additionally, using medicated creams (e.g., benzocaine, hydrocortisone) is not recommended without instruction from the child’s pediatrician. Caregivers should keep sunburned children out of the sun entirely until sunburn heals completely and practice sun protection moving forward to prevent burning again.³

Parents and caregivers should always treat sunburn on a baby younger than 1 year old as an emergency.³ Advise them to call the child’s pediatrician immediately or seek care from an urgent care or emergency department if outside business hours. For a child 1 year or older, caregivers should seek medical attention if they have severe pain, blistering, lethargy, or fever more than 101°F.³ They should also contact a medical professional if their sunburned child is not urinating regularly, as this is a sign of dehydration and can be an emergency.³

CONCLUSION

Sunburn is a major public health issue. Although the last few decades have seen major research linking sunburn to skin cancer, individuals continue to overexpose themselves to harmful UV radiation. Many myths circulate about suntanning and sunburn. Pharmacy teams should remind patients that there is no such thing as a “healthy tan” and they don’t need to sit directly in the sunlight on a hot, sunny day to get a sunburn. They should also help people navigate the sunscreen aisle, as not all sunscreens are created equal. Ensure patients know how to properly apply the sunscreen of their choice, and encourage adherence to reapplication at recommended intervals. When patients approach the pharmacy with an active sunburn, pharmacy technicians should refer them to the pharmacist for counseling about appropriate treatment, when to seek medical attention, and how to adequately protect themselves in the future.

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