Is Sunscreen Safe?

In this article:
How are sunscreens tested?
What is the UK’s UV star rating?
Ultraviolet (UV) filters in sunscreens
Which UV filters are most likely to cause an allergic reaction?
Are UV filters absorbed by the body?
Do sunscreens trigger free radical damage in skin?
Is it safe to use sunscreen during pregnancy?
What about UV filters disrupting hormones?
Is avobenzone unstable?
What about sunscreens and coral reefs?
What we know about coral reefs and sunscreen
What we don’t know
Should you wear sunscreen when swimming?

Yes, sunscreens are safe for everyone. In fact, when applied as instructed (which is described on every sunscreen’s label) they save lives and prevent a wide range of skin problems. Decades of people using sunscreen and extensive, world-wide research has proven this to be true (1).

While sunscreen safety studies are ongoing and some knowledge gaps exist, from the dozens of studies we’ve reviewed there’s no evidence anyone should give up sunscreen and risk the consequences for their skin.

Research has proven beyond any doubt that the ultraviolet (UVA and UVB) radiation the sun emits is the most prevalent carcinogen on our planet. It not only affects everyone’s skin but also their eyes and internal organs (2). Avoiding sunscreen and not following sun smart behavior isn’t just detrimental to your skin, it’s bad for almost every aspect of your health (3). Because of these established-beyond-a-doubt dangers, we should be far more worried about the sun than sunscreens. Board-certified dermatologist Dr. Debra Jaliman recommends, “using a broad-spectrum sunscreen daily, reapplying regularly and avoiding the midday sun”.

Below we address common questions from our consumers about sunscreens and UV filters. We hope that you find this research-supported information reaffirming and reassuring.

How are sunscreens tested?

Sunscreens produced in the United States and sold throughout the European Union and United Kingdom must go through rigorous testing to determine their SPF rating. They’re also subject to a critical wavelength test which evaluates the broad-spectrum protection. The critical wavelength test is considered extremely reliable because it uses the full spectrum of UV radiation (UVA and UVB) skin is exposed to in real-world settings (4).

Currently, the SPF rating on any sunscreen is still about UVB protection. If a sunscreen passes the critical wavelength test, it can legally state “broad spectrum” on its label. To pass, the sunscreen’s UVA protection must be at least one-third of its UVB protection. This result is also referred to as UVA-PF (protection factor).

Every Paula’s Choice sunscreen undergoes US Food & Drug Administration (FDA) and Colipa (Europe’s cosmetic regulatory body) testing. Each one reliably falls in the range of offering high protection (SPF 30–49.9) or very high protection (SPF 50 and greater).

Note: The PA+ (Protection of UVA) rating system, a method used to determine the amount of UVA protection a sunscreen provides, is used outside of the United States America, most notably in Asia and parts of Europe.

What is the UK’s UV star rating—and why don’t Paula’s Choice sunscreens have it?

The UV star rating system was developed by a drugstore chain based in the United Kingdom. It is meant to give consumers more information on how much UVA protection a sunscreen provides, via a star ratings system. The star ratings go from three to five, with the five-star rating pertaining to the sunscreens whose UVA protection is at least 90% of its UVB protection.

Although well-meaning, this system can be misleading since it measures how evenly the sunscreen protects in the UVA range, not how strong (thus, how effective) that UVA protection is over a period of time. In other words, the UVA protection could earn five stars even though its strength is lower than a sunscreen without this rating (5).

This rating system is not required for brands to sell sunscreens in the UK. That’s an important distinction because if sunscreen regulators in other parts of the world felt this rating system was superior to others it would be mandatory, not optional.

Ultraviolet (UV) filters in sunscreens

UV filters in sunscreen come in two “flavours”, organic and inorganic. Although the term organic is strongly associated with natural, in this case organic UV filters refers to synthetic options such as octinoxate, octisalate, and avobenzone. Inorganic UV filters refer to the mineral-derived ingredients titanium dioxide and zinc oxide (36).

Depending on the filters chosen, they work individually or together to help defend skin from the visible damage that ultraviolet A (UVA) and ultraviolet B (UVB) radiation have on skin. If you want to know more, learn more about the difference between UVA and UVB rays.

Which UV filters are most likely to cause an allergic reaction?

UV filters are generally well tolerated, although some can be more sensitising than others. Among common UV filters, oxybenzone and octocrylene are the most likely to cause an allergic reaction. (4, 6, 7).

It’s important to point out that it is not clear from the research if the reactions some people experience are from these UV filters or something else in the sunscreen formula, such as fragrance, a combination of ingredients, or a cross-reaction with other skin care products. Even the mineral actives (titanium dioxide and zinc oxide), have slight potential to trigger an allergic response on skin, although this is considered much less likely than synthetic sunscreens (8).

Both forms of Tinosorb, a UV filter approved in Europe for over two decades, have random reports of causing allergic reactions, but those are rare. These effective sunscreen actives are still considered a good choice for those with sensitive skin. It’s recommended those with very sensitive skin patch test products containing these ingredients to see if it works for them (25).

Are UV filters absorbed by the body?

Studies on nano-sized titanium dioxide and zinc oxide have shown they do not absorb past the uppermost layers of skin (9). Other types of UV filters, such as oxybenzone, octinoxate, octocrylene, and octisalate can be absorbed by the body, but the amount is so minimal it’s barely measurable. The amounts are typically measured in nanograms, or one-billionth of a gram (picture adding one drop of water to a swimming pool).

Historically, studies trying to scare people about sunscreens absorbing into the body base their results on amounts no person would ever apply, and these tests are almost always done on animals. For example, a person would need to apply sunscreen for decades to hundreds of years to come close to matching the amounts used in animal tests (4, 10).

More recent research looking at absorption of select UV filters into the body has shown this can occur; however, what’s important to know is that the presence of small amounts of UV filters in the body has never been shown to cause harm to people. Research pointing in this direction uses suggestive wording such as “might be,” “could potentially,” or “is associated with.” In short, correlation doesn’t prove causation (10).

And, like numerous other substances that enter the body via skin or simply from breathing, the body metabolises and eventually eliminates them. Animal studies showing evidence of UV filters accumulating in the body were either done with UV filters no longer in use or had results indicating no negative effects (11, 12, 13).

Do sunscreens trigger free radical damage in skin?

Studies have shown that some UV filters used in sunscreens can trigger free radical damage on skin’s surface in the presence of daylight; however, this damage is considered short-lived and easily remedied by choosing a sun cream that contains antioxidants. For certain, exposing skin to UV radiation without sunscreen triggers an enormous amount of free radical damage impacting every layer of skin (14,15).

Is it safe to use sunscreen during pregnancy?

Doctors caring for those who are pregnant typically encourage sunscreen usage. Daily application to facial and neck skin can help prevent a pregnancy-related discolouration concern known as melasma from worsening (16). The mineral UV filters titanium dioxide and zinc oxide tend to be recommended above others due to their excellent safety profile and low risk of triggering a sensitised response (8).

Oxybenzone is the UV filter that pregnant people are most concerned about using. Studies in people and animals have shown oxybenzone has an estrogenic effect; however, this activity is considered weak, and some studies have shown no such effect (24). Moreover, the small amount of this ingredient capable of getting into the body via topical application is metabolised and excreted, just like similar water-soluble ingredients (17).

Research on pregnant women using sunscreens with 6% oxybenzone has shown that enough of it can penetrate the skin, enter the body, and can cross the placental barrier. But just because fetal exposure to oxybenzone in sunscreen is possible does not mean any harm is being done; oxybenzone has never been shown to cause any type of birth defect.

Interestingly, some studies have shown that oxybenzone itself isn’t to blame, but instead a metabolite (4-hydroxy-benzophenone) of this ingredient is the issue. This metabolite comes from benzophenone, a chemical used in pharmaceuticals, recycled paper, inks, furniture, paints, lacquers, even as a flavouring in candy. This means it’s impossible to avoid any exposure to these ingredients, but you can certainly opt to avoid sunscreens that contain oxybenzone (18).

We certainly understand wanting to take extra precautions during this time, and research has shown the mineral sunscreen actives of titanium dioxide and zinc oxide are excellent alternatives—even when nano-sized (19).

What about UV filters disrupting hormones?

Along with oxybenzone, other UV filters such as homosalate, octinoxate, and octocrylene are accused of being hormone disruptors. This effect has primarily been demonstrated via oral intake of substantial amounts of these ingredients or on isolated cells. In cases where a hormonal change was measured via topical application, the difference was one million-fold less than what was measured from normal hormonal activity in the body. Studies involving people have shown that common UV filters do not have a biologically significant effect on hormones. (20, 26).

Is avobenzone unstable?

Avobenzone is often touted as being unstable in the presence of sunlight. Although this is true when avobenzone is examined on its own, chemists who formulate with sunscreen ingredients know avobenzone’s pros and cons. As such, they can formulate with this UV filter in ways that improve its stability in sunscreens, such as using antioxidants and UV filters like octocrylene. A newer formulary strategy is encapsulation technology that also works to keep the UV filter where it’s needed most—the skin (21, 22).

What about sunscreens and coral reefs?

The consequences of UV filters in the ocean are still not well understood. Some scientists disagree about how much risk UV filters pose to coral reefs in real-world settings where a vast body of water—the ocean—is in constant motion and exposed to numerous natural and human-triggered elements that are not included in lab studies (1).

But this does not mean zero risk to corals from sunscreen use; instead, it’s a risk/benefit analysis that considers coral reef and human health. The need to protect our skin from UV light is dire since hundreds of studies have conclusively shown such exposure is harmful not just to your skin but to your overall health and well-being (34).

What we know about coral reefs and sunscreen

There is limited evidence from both lab and ocean studies that some UV filters are associated with damage to coral reefs (27, 28). However, there is also evidence that corals in remote parts of the world—meaning limited human contact—have often suffered extensive damage due to rising carbon dioxide levels that trigger ocean acidification and from the threat of invasive species (30, 31).

We also know that trying to reproduce a coral’s natural environment in a lab setting is difficult. It’s hardly an apples-to-apples comparison with an ocean environment. As the authors of an extensive review of this topic commented, “Corals require specific lighting conditions, temperatures, feeding and nutrition, water quality and flow for optimal health, which are often species‐ and life stage–specific; and acceptable variations are often very tightly bound ranges.” This means a slight or unaccounted for deviation in a lab setup could significantly impact corals, making UV filters innocent bystanders or unjustly implicated (29).

Interestingly, we also know that several lab and ocean-sampled studies of water from reef-populated areas had methodology omissions and reporting issues that call into question the results obtained (29). And several studies using seawater samples did not take additional samples at different periods of time—an essential step to understand if levels of the UV filters vary and if so, by how much? In short, more detailed, better-designed studies are needed before we can blame any UV filter for coral demise.

Specific UV filters (oxybenzone, octinoxate, and zinc oxide) have been shown in lab settings to cause damage to corals. These same filters have been measured in some reefs at levels which lab tests have shown cause bleaching, a sign of poor health (29). The presence of these UV filters in seawater is likely from sunscreen breakdown from people swimming in the ocean, but other contributors include wastewater effluent discharged into the ocean (meaning the sunscreen people wash off when they shower) as well as industrial and agricultural waste since UV filters like oxybenzone and zinc oxide are used in a wide range of products. La Niña and El Niño weather patterns that lead to oceans heating up are major culprits, and it’s been observed in many areas corals can recover from these temperature swings and be better able to withstand future damage (23, 35).

What we don’t know

Banning UV filters such as oxybenzone from use in sunscreens may seem like a good solution, but there’s a lack of evidence that so-labeled ‘reef safe’ UV filters are less harmful to corals. More important, scientists who’ve analysed this concern in depth are dealing with data gaps that preclude them from stating with certainty that sunscreen use by people swimming in the ocean is a significant threat to coral reefs. Scientists also caution that the use of alternative UV filters could have similar or more complex outcomes (29).

We also don’t know precisely how much damage people’s use of sunscreen while in the water is impacting corals. There are far too many variables, all believed to contribute in small and large ways to coral damage. Avoiding certain UV filters prior to going in the ocean isn’t likely to move the needle in a significant way.

Should you wear sunscreen when swimming?

Continue using water-resistant sunscreen when swimming. Do not forgo this step! Filters measured in greater numbers in or near coral reefs include oxybenzone, octinoxate, octocrylene, and homosalate. Even though strong risk hasn’t been firmly established, you may wish to avoid those filters in water-resistant sunscreens when you know you’ll be going in the ocean. Instead, look for those that contain titanium dioxide, non-nano zinc oxide, avobenzone, ecamsule, octyl triazome, octisalate, or drometrizole, all considered to be “reef-safe,” although this status may change as further studies are done.

Keep this issue in perspective: One retrospective research paper commented “…it is important to note the magnitude of UVF [ultraviolet filters] effects is far below other factors endangering coral reefs (ocean acidification and loss of CO2 metabolism from plankton)” (13). Yet another stated: “While climate change alone is a major threat to coral reefs, it cannot be considered in isolation when local human activities are severely damaging coral reefs. These include direct damage and sedimentation from coastal development, pollution from land‐use change, increased nutrients from agriculture, invasive species, overfishing and destructive fishing practices.” (32)

No single sunscreen formula or UV filter is perfect. Each has pros and cons, but what we know without a doubt is that UV radiation generated by the sun is a serious global carcinogen (33). Sun-smart behavior is critical for the health and long-term appearance of your skin, and this includes applying sunscreen to areas not covered by sun-protective clothing and actively engaging in sun-smart behavior year-round, which includes not tanning (even when on vacation) wearing a hat and sunglasses, and reapplying sunscreen to areas of exposed skin when outdoors.

Learn more about sunscreen and skin care ingredients.

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30. Scientific Reports, December 2015, pages 1–8
31. Advances in Marine Biology, Volume 87, Issue 1, 2020, pages 259–290
32. Ecology and Evolution, June 2018, pages 6,354–6,368
33. Molecules, Volume 24, April 2019, pages 1–27
34. Advances in Experimental Medicine and Biology, Volume 996, November 2017, pages 207–219
35. Limnology and Oceanography, March 2022 pages 1–15
36. Skin Pharmacology and Physiology, November-December 2005, pages 253–262