The Ultimate Guide To Sunscreen Ingredients

Skin care experts break down some of the head-scratching terminology.

by Hilary Shepherd
Originally Published: 
Sunscreen ingredients can be confusing and shady marketing tactics don't help. Here's advice on how ...
Suncare Month

Shopping for a new sunscreen seems like an easy enough task — until it isn’t. In addition to the various forms of SPF (like lotions, sticks, sprays, powders, and so on), scientific terms and confusing jargon on ingredients labels can make the sunscreen market feel overwhelming. What actually is “non-nano?” What about “reef-safe?” Do the words “clean” and “natural” mean it’s a better formula? Sigh.

If the ever-growing (and ever-evolving) verbiage surrounding SPF has forced you to simply reach for the first sunscreen you come across, well, understandable. But it’s important to take the time to research what some of these terms actually mean — and more better yet, which words are worth paying attention to and which ones are hollow marketing claims.

You already (hopefully) know how vital wearing sunscreen is — and not just during the summer months, but all year long — but there’s a lot more to know about SPF ingredients. Start with the basics: See that SPF rating displayed on the front label? A super high number, like 70 or 100, won’t make you indestructible (sorry) or dramatically lessen your potential for sunburn. Narrow your search by seeking out products with an SPF of at least 30, says Kristine Keheley, co-founder and chief formulator of Taos AER and Vapour Beauty, because it blocks 97 percent of the sun’s UVB rays and is the baseline level of sun protection recommended by the American Academy of Dermatology (AAD).

Next, decide what type of sunscreen is right for you by learning about the three main categories: mineral (or physical), chemical, or a combination of both. The different ingredients and methods of sun protection in each can feel a bit science-y and technical, but it’s worth figuring out your type, as one might work significantly better for you than another, notes Cocokind founder Priscilla Tsai. After you determine which category is best for your skin, you can start whittling down options by price, brand values, actual trial of formula, and more, she adds.

SPF should be applied thoroughly (as a rule of thumb: the equivalent of a shot glass on your body and two finger lengths on your face) and frequently (every two hours at least), says Dr. Naana Boakye, board-certified dermatologist and dermatology director for KINLÒ, so it’s essential to find a sunscreen that you truly love to apply... and reapply, and reapply. It might involve a bit of trial and error, but frankly, your skin depends on it.

To make the dizzying world of SPF labels slightly less mystifying, Bustle asked a slew of experts, from cosmetic chemists to skin care founders to dermatologists, to translate commonly found SPF terms to better understand — and shop for — sunscreen. Read on for your unofficial sunscreen glossary.

Decoding Your Sunscreen’s Ingredients Label

Broad Spectrum:

Charlotte Chen Pienaar, founder of Everyday Humans, deems this term the most important one to pay attention to when shopping for SPF. “It indicates that the sunscreen provides protection against both UVA and UVB rays,” she tells Bustle. Here’s why you’ll want protection from both: UVB rays cause burning and reddening of the skin, while UVA rays are primarily associated with skin aging and wrinkling. (Both contribute to skin cancer.) According to Dr. Aimee Paik, board-certified dermatologist and senior vice president of dermatology for Hims and Hers, popular ingredients with broad-spectrum protection include zinc oxide and titanium dioxide, so keep an eye out for those while reading the back of a bottle.

Chemical Sunscreen:

This category contains organic compounds that protect skin by absorbing UV rays, says Ron Robinson, cosmetic chemist and founder of Beautystat Cosmetics. Active ingredients like oxybenzone, avobenzone, and octisalate melt into skin and convert UV rays into heat, which is then released from the skin. This makes for a broad-spectrum formula that’s thinner, easier to apply, and less likely to leave a white cast.


You might see the word “clean” thrown around specifically in reference to mineral or physical sunscreens because the filters in them sit on your skin’s surface and deflect harmful rays instead of absorbing them and turning them into heat like chemical sunscreens do, says Pienaar. But a 2016 study found that zinc oxide and titanium dioxide — two active ingredients found in mineral sunscreens — can also provide protection via absorption. Essentially, “the terminology of ‘clean’ versus ‘not clean’ has created a lot of misconceptions,” she says. What’s more, the word “clean” can be particularly misleading because it can mean different things to different people, adds Dr. Jessica Wu, a board-certified dermatologist and OFF! partner. “A lot of times, you have to think about where the information is coming from. Is someone describing a clean sunscreen and also trying to sell you that same clean sunscreen? It’s important to look at non-biased sources for science-based facts, like Mayo Clinic and AAD,” she says.

Clear Zinc or Sheer Zinc:

Zinc oxide — a hero ingredient of mineral sunscreens due to its strong broad-spectrum protection, water-resistant nature, and antibacterial properties — used to have one major drawback: being thick, pasty, and white. Today’s sunscreens have mostly evolved to eradicate those concerns (thanks to micronization), but consider seeking out labels that say “clear zinc” or “sheer zinc” anyway for added assurance, suggests Wu. “A lot of them are really wonderful and more appropriate for those of us with more richly melanated skin.”

Mineral or Physical Sunscreen:

A mineral sunscreen means that it contains naturally occurring minerals — like titanium dioxide and zinc oxide — that physically block and deflect both UVA and UVB rays, says Robinson. If you have sensitive skin, consider going this route as mineral-based sunscreens tend to cause less irritation than chemical sunscreens, adds Banish founder Daisy Jing.


Use caution when you encounter this term, says Jodi Scott, CEO and cofounder of Green Goo. “The word ‘natural’ is not regulated, so a sunscreen label can state that it’s natural while still containing chemicals like oxybenzone,” she tells Bustle. “[Some] sunscreen companies employ this tactic, and it’s a deceptive practice.” Because of the murkiness of the term, it’s a good idea to read labels and research the ingredients from unbiased, objective sources.


If you’re acne-prone, or just want a formula that won’t clog pores, a sunscreen labeled as “non-comedogenic” might seem appealing. But according to cosmetic chemist and founder of KKT Consultants Krupa Koestline, the term is outdated. “Most products aren’t tested for comodegenity as testing is expensive, so brands base the claim on the ingredient list,” she says. “But finished products may not behave the same way as the raw ingredients do before they’ve been manipulated during the manufacturing process.” The bottom line, according to Bolden cofounder Chinelo Chidozie, is that there’s no standard way to confirm that a formulation is in fact non-comedogenic, so the term isn’t objective and can be misleading.

Non-Nano or Nano-Free:

Nanoparticles are the ingredients found in mineral or physical sunscreens (zinc oxide and titanium dioxide) that have been specifically micronized or finely grounded in order to apply more easily — and more sheer — on the skin, explains Robinson. When data a few years ago showed that small amounts of nanoparticles could be absorbed by the body, concerns led to the popularity of terms like “non-nano” and “nano-free.” But further studies of nanoparticles actually crossing the skin barrier, seeping into the bloodstream, and affecting health are largely lacking, says Jing.


If you’ve ever spotted “PA” on a sunscreen label followed by one (or several) plus signs, know that it’s an indicator of UVA protection. This rating system was developed in Japan in the mid-’90s, with more pluses denoting a higher level of protection. PA, which stands for “Protection Grade of UVA,” isn’t just seen on Japanese sunscreens — you might find the symbol next to the SPF rating on American sunscreen labels, too. If so, look for one with four or five plus signs for maximum, broad-spectrum protection, says Koestline.


A reef-safe sunscreen means that it’s devoid of ingredients that can harm coral reefs. Historically, explains Tsai, the term has been associated with mineral-only SPFs because they don’t include certain UV filters, like oxybenzone and octinoxate, that can be toxic to marine life. “But that isn’t completely accurate,” she says. “The reality is that studies show [many] sunscreen filters — even zinc — at very high levels can cause coral reef damage.” Plus, she adds, “existing research doesn’t translate to what’s actually happening when sunscreen is introduced to the ocean from humans at normal levels.” Given the limited nature of studies on this topic, Tsai suggests still wearing water-resistant sunscreen when swimming in the ocean.


This acronym stands for “Sun Protection Factor” and measures how effective a sunscreen is at protecting your skin from ultraviolet (UV) radiation. It’s accompanied by a number, or rating, which tells you how long a sunscreen will protect you from sunburn based on how long it takes your skin to burn, and it’s all thanks to a nifty formula: Multiply the SPF rating by the number of minutes it takes for your skin to burn in the sun sans protection. For example, if it takes your skin 10 minutes to burn when it’s unprotected, applying a sunscreen with SPF 30 means it’ll take 30 times longer for you to get sunburned. That doesn’t mean you can simply slather it on once and bask blissfully in the sun for five hours, though: The AAD suggests reapplying sunscreen at least every two hours for maximum protection, especially if you’re swimming or sweating. Also, remember that SPF is a measurement of UVB radiation only, says Boakye.


This means that a sunscreen remains effective while swimming or sweating. The specific length of time it remains effective — either 40 or 80 minutes — is based on regulated SPF testing and will be clearly shown on the front label. The term has replaced words like “waterproof” or “sweatproof,” which were banned by the U.S. FDA in 2011 because they were misleading — all sunscreens eventually wash off. If a sunscreen doesn’t say “water-resistant,” notes Koestline, the label must direct the user to reapply it every two hours or use a water-resistant sunscreen if swimming or sweating.

Studies referenced:

C Cole, T Shyr, H Ou-Yang. (2016). Metal oxide sunscreens protect skin by absorption, not by reflection or scattering. 32(1):5-10. Photodermatol Photoimmunol Photomed.

R, Pati et al. (2014). Topical application of zinc oxide nanoparticles reduces bacterial skin infection in mice and exhibits antibacterial activity by inducing oxidative stress response and cell membrane disintegration in macrophages. 10(6):1195-208. Nanomedicine.

B, Gulson et al. (2010). Small amounts of zinc from zinc oxide particles in sunscreens applied outdoors are absorbed through human skin. 118(1):140-9. Toxicol Sci.

S, Wong et al. (2020). Sunscreens containing zinc oxide nanoparticles can trigger oxidative stress and toxicity to the marine copepod Tigriopus japonicus. 154:111078. Mar Pollut Bull.

G, Puccetti, H, Fares. (2014). A new approach for evaluating the water resistance of sunscreens on consumers: tap water vs. salt water vs. chlorine water. 36(3):284-90. Int J Cosmet Sci.


Charlotte Chen Pienaar, founder of Everyday Humans

Dr. Aimee Paik, M.D., board-certified dermatologist at Salinas Valley Memorial Healthcare System and senior vice president of dermatology for Hims and Hers

Ron Robinson, cosmetic chemist and founder of Beautystat Cosmetics

Daisy Jing, founder of Banish

Jodi Scott, CEO and co-founder of Green Goo

Dr. Jessica Wu, M.D., board-certified dermatologist at Dr. Jessica Wu and OFF! partner

Chinelo Chidozie, co-founder of Bolden

Priscilla Tsai, founder of Cocokind

Dr. Naana Boakye, M.D., M.P.H., board-certified dermatologist at Bergen Dermatology and dermatology director for KINLÒ

Krupa Koestline, cosmetic chemist and founder of KKT Consultants

Kristine Keheley, co-founder and chief formulator of Taos AER and Vapour Beauty

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