Are sunscreens safe? Evidence and risks

Questions about absorption, hormones, or vitamin D deserve precise answers. We review what has been proven, what is still being studied, and how to choose and use sunscreen without alarmism or promises of zero risk.

Summary in 60 seconds

• Yes, they are generally safe: the available evidence supports continuing to use sunscreens as part of sun protection. This does not mean that all formulas are the same, that none can cause discomfort, or that all questions about their ingredients have been answered.
• Some filters can be absorbed and detected in the blood. Detecting a substance shows exposure, but does not by itself prove that it causes harm. Absorption studies warrant further research; they do not indicate that we should stop using sunscreen.
• For everyday use, look for broad-spectrum protection with SPF 30 or higher, choose a formula you tolerate, and follow the application instructions. Reapply while outdoors and combine the product with clothing, a hat, and shade. No sunscreen blocks all radiation or makes unlimited sun exposure safe.

What is sunscreen and why does it matter?

Sunscreen is a product that reduces the amount of ultraviolet radiation that reaches the skin. Its function is not only to prevent redness: it is part of preventing cumulative sun damage.

The risk of ultraviolet radiation has been proven

Ultraviolet radiation can cause sunburn, accelerate skin aging, and contribute to the development of cancer. Furthermore, its intensity is not solely dependent on heat: significant exposure can occur on cool or cloudy days. The World Health Organization recommends taking protective measures when the UV index reaches 3 or higher. WHO 2022 .

The benefits of the protector are well-documented, but there are also limitations.

In an Australian trial, daily application for approximately four and a half years reduced the number of squamous cell carcinomas, a type of skin cancer, by 39% . This figure refers to the number of tumors, not an identical reduction in the individual risk of any cancer. Green 1999 .

Subsequent follow-up recorded 11 melanomas in the daily-use group and 22 in the group using sunscreen at their discretion. The result suggests a benefit, but there were few cases and the overall estimate had statistical uncertainty. Therefore, claiming that sunscreen guarantees to «halve the risk of melanoma» oversimplifies the evidence. Green 2011 .

It also helps prevent photoaging.

Another analysis of the trial found less progression of sun-induced skin aging among those who used sunscreen regularly. It is a preventative measure, not a promise to eliminate wrinkles or reverse all previous damage. Hughes 2013 .

How does sunscreen work?

Sunscreens contain filters that interact with ultraviolet radiation and reduce the amount that reaches the skin. These are usually mineral filters, such as zinc oxide and titanium dioxide, and organic filters, commercially known as «chemical» filters.

The explanation that minerals only act as mirrors and others only absorb radiation is incomplete. Zinc oxide and titanium dioxide also provide much of their protection by absorbing ultraviolet radiation . Cole 2016 .

Furthermore, minerals are also chemical substances. Therefore, the words mineral , chemical , or natural are not enough to judge safety: the ingredient, its concentration, the formulation, and the route of exposure must all be evaluated.

And what about nanoparticles?

In a study with volunteers, repeated application of zinc oxide nanoparticles for five days showed no penetration of the particles into the viable epidermis —the part of the epidermis that contains living cells— nor local cellular toxicity.

What do we know about their safety?

Absorption into the blood: exposure does not equate to damage

• A trial with 48 adults found that six sunscreens could be absorbed and detected in the blood. The concentrations exceeded a regulatory threshold used to determine whether further safety studies are needed; it was not a threshold of proven toxicity .
• The study evaluated absorption under conditions that included intensive application over a large body surface. It did not investigate the development of cancer, infertility, or other diseases after years of use. Its authors noted that the results did not indicate that people should stop using sunscreen. Matta 2020 .

Possible hormonal effects: legitimate questions, not automatic conclusions

• Some filters have shown experimental signs that warrant investigating possible hormonal effects. When evaluating oxybenzone—also called benzophenone-3—the European Union’s Scientific Committee on Consumer Safety considered the evidence regarding its potential hormone-disrupting properties inconclusive.
• That assessment also did not provide blanket approval: it established different safety conditions depending on the concentration and type of product. For example, it did not consider a 6% concentration safe for certain body formulations. The assessment is done ingredient by ingredient and according to exposure , not through a general classification of “all safe” or “all hazardous.” SCCS 2021 .

Regulatory decisions are also specific

• In June 2026, the FDA added bemotrizinol , a broad-spectrum organic filter with low systemic absorption, to the list of ingredients recognized as safe and effective under the conditions authorized in the United States. FDA 2026a .
• Furthermore, on September 10, 2026, the FDA issued an order to exclude PABA and trolamine salicylate due to safety concerns. It clarified that it was unaware of any sunscreens currently sold in the United States that contained these ingredients. These are decisions regarding specific ingredients within a specific regulatory framework, not a demonstration that all organic sunscreens are dangerous. FDA 2026b .

Irritation and allergies: real problems that need to be addressed

• A formula can cause dermatitis. The culprit could be a filter or one of the other components, such as a fragrance. Allergy testing studies confirm that both active ingredients and other components can be involved.
• If a product causes a persistent reaction, discontinue use and seek further evaluation. Just because one sunscreen irritates you doesn’t mean they all will; identifying the culprit allows you to choose alternatives. In the meantime, maintain sun protection through clothing and shade. Warshaw 2013 .

Benzene contamination: a quality problem, not a problem with all sunscreens

• Certain products have been recalled due to contamination with benzene, a carcinogenic substance. This is a problem that requires manufacturing controls and the recall of affected products; it should not be underestimated.
• However, this does not prove that all sunscreens contain benzene or that sunscreen use, as a category, causes cancer. The recommendation is to avoid using the recalled products and continue sun protection with appropriate alternatives . FDA sf

How to choose and how to use it?

Choose the protection, not just the filter name

• Look for SPF 30 or higher and broad-spectrum protection , meaning protection against both UVA and UVB rays. If you’re going to swim or sweat, choose a water-resistant product. Remember that sunscreen complements clothing, shade, and reducing intense sun exposure; it doesn’t replace them. WHO 2024 .

Apply a sufficient amount and don’t forget to reapply.

• Follow the package instructions; it usually recommends applying it about 15 minutes before going outside. As a guide, an average-sized adult needs about 30 mL to cover a large portion of their body when uncovered . Adjust the amount according to the exposed area.
• Reapply approximately every two hours while outdoors and after swimming, sweating heavily, or toweling off, as directed on the label. Check the expiration date and avoid storing the container in direct sunlight or excessive heat. FDA 2026c .

When using aerosols, be careful with your clothing and avoid inhaling them.

• Do not spray directly onto the face or near the mouth. For the face, apply the product to your hands first. Avoid using it in windy conditions and spread it evenly over the skin for uniform coverage.
• Do not apply near flames, cigarettes, or heat sources: some formulations are flammable. A cream or lotion is a practical alternative when spray control is difficult. AAD 2025b .

Common mistakes

Apply very little. An insufficient layer will not provide the protection rated for the product. Don’t forget exposed areas such as the ears, neck, or tops of the feet.

Thinking that a high SPF lasts all day is a misconception. A higher number doesn’t eliminate the need to reapply.

Confusing water resistance with waterproofing. Swimming, sweating, and towel drying necessitate following reapplication instructions. AAD 2025a .

Using sunscreen as permission to prolong sun exposure is not intended to reduce damage during exposure, nor to compensate for additional hours in the sun. WHO 2024 .

The recommendation is not to ignore doubts, but to interpret them correctly. Use appropriate sunscreen, heed warnings about specific products, and combine its application with clothing and shade. Further research into sun safety and continued prevention of sun damage are compatible goals. FDA 2026b .

Frequently Asked Questions

Is it safe to use sunscreen every day?

• For most people, regular use is part of the recommended sun protection when outdoors. The important thing is to use a well-tolerated formula and combine it with other measures, without interpreting «daily use» as a guarantee of zero risk. AAD 2025a .

Are mineral sunscreens always safer?

• There is no universal rule. Zinc oxide and titanium dioxide are useful options, but safety depends on the formulation and the context. Nor do all organic filters have the same profile: bemotrizinol, for example, was recognized by the FDA as safe and effective under authorized conditions. FDA 2026a .

Can sunscreen decrease vitamin D?

• Yes, it can have an influence. The Sun-D trial, published in 2025, found lower vitamin D levels with regular use of SPF 50+ for about a year compared to discretionary use. At the end of the trial, 45.7% of the regular-use group and 36.9% of the comparator group were below the deficiency threshold used; this result was exploratory. (Tran 2025 )
• This does not mean that sunscreen use should be discontinued. Diet, personal risk factors, and, where appropriate, clinical assessment and supplementation can be used to address this issue. Not everyone who uses sunscreen automatically needs testing or supplements. AAD 2025a .

Which protector is best during pregnancy?

• Sun protection remains important. The American Academy of Dermatology recommends formulas containing zinc oxide, titanium dioxide, or both to reduce irritation, along with clothing and shade.
• This recommendation does not prove that prior use of another contraceptive has caused harm to the pregnancy. Any questions about a specific formula can be discussed with your prenatal care team. AAD 2025c .

Can you apply sunscreen to a baby?

• For infants under six months, the priority is to avoid direct sunlight and use shade, appropriate clothing, and a hat. The FDA recommends consulting with a pediatrician before applying sunscreen.
• This sunscreen should not be used as permission to keep a baby in the sun. Physical protection and preventing overheating are essential measures. FDA sf

What should I do if I have sensitive skin or eczema?

• Choose based on your tolerance and skin type, not just on claims like «for sensitive skin.» If a formula triggers itching, redness, or a persistent rash, stop using it and consult a doctor.
• It may be necessary to identify a filter, fragrance, or other responsible component. Assessing for a possible allergy helps avoid specific ingredients without abandoning all sun protection. Warshaw 2013

Is environmental safety the same as safety for people?

• No. These are frequently related but different questions. An effect on aquatic organisms does not automatically demonstrate toxicity to a person applying the product to their skin (or vice versa).
• A report by the U.S. National Academies identified gaps in knowledge regarding exposure and environmental effects and recommended a formal ecological risk assessment. The response must protect human health and ecosystems, not replace uncertainty with unprotected sun exposure. NASEM 2022 .

Bibliography and sources

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• American Academy of Dermatology. Sunscreen FAQs [Internet] . Rosemont (IL): AAD; 2025 [actualizado 11 feb 2025; citado 14 sep 2026] .
• World Health Organization. Ultraviolet radiation [Internet] . Geneva: WHO; 2022 [citado 14 sep 2026] .
• Green A, Williams G, Neale R, Hart V, Leslie D, Parsons P, et al. Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomized controlled trial . Lancet. 1999;354(9180):723-9. doi:10.1016/S0140-6736(98)12168-2.
• Green AC, Williams GM, Logan V, Strutton GM. Reduced melanoma after regular sunscreen use: randomized trial follow-up . J Clin Oncol. 2011;29(3):257-63. doi:10.1200/JCO.2010.28.7078.
• Hughes MCB, Williams GM, Baker P, Green AC. Sunscreen and prevention of skin aging: a randomized trial . Ann Intern Med. 2013;158(11):781-90. doi:10.7326/0003-4819-158-11-201306040-00002.
• Cole C, Shyr T, Ou-Yang H. Metal oxide sunscreens protect skin by absorption, not by reflection or scattering . Photodermatol Photoimmunol Photomed. 2016;32(1):5-10. doi:10.1111/phpp.12214.
• Mohammed YH, Holmes A, Haridass IN, Sanchez WY, Studier H, Grice JE, et al. Support for the safe use of zinc oxide nanoparticle sunscreens: lack of skin penetration or cellular toxicity after repeated application in volunteers . J Invest Dermatol. 2019;139(2):308-15. doi:10.1016/j.jid.2018.08.024.
• Scientific Committee on Consumer Safety. Opinion on benzophenone-3: SCCS/1625/20 [Internet] . Brussels: European Commission; 2021 [citado 14 sep 2026] .
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• Warshaw EM, Wang MZ, Maibach HI, Belsito DV, Zug KA, Taylor JS, et al. Patch test reactions associated with sunscreen products and the importance of testing to an expanded series: retrospective analysis of North American Contact Dermatitis Group data, 2001 to 2010 . Dermatitis. 2013;24(4):176-82. doi:10.1097/DER.0b013e3182983845.
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