How to Choose the Best Sunscreen for Your Skin: Which Ingredients to Look For and Which Ones to Avoid

We all know that daily sun protection is key to prevent sunburns, skin cancer and premature aging. But not all sunscreens are made equal—so yours may not be as safe or as effective as you think.

In 2022, a study of 51 common US sunscreens found that the majority of them had lower SPF numbers than claimed, according to laboratory testing. In fact, the average SPF was only 42% of what was on labels, which means a so-called SPF 30 might only be an SPF 12-13.¹

But that’s not all. In the same study, researchers also measured how well the sunscreens protected against UVA (the most prevalent and dangerous form of UV). Although the products were labelled as “broad-spectrum”—defending against both UVA and UVB—they actually provided significantly lower UVA protection than implied.¹

So how can you be sure that your sunscreen is doing its job? Read on to find out exactly what to look for and why.

Is Mineral or Chemical Sunscreen Better?

The first choice to make is whether you’re going to use a mineral vs chemical sunscreen. Mineral sunscreens protect your skin with naturally-occurring minerals, while chemical sunscreens use synthetically-derived ingredients.

Scroll to Continue

Golden Globes 2025: The Best (And Worst) Celebrity Hair and Makeup Looks on the Red Carpet

Palm Springs Film Festival 2025: The Best (And Worst) Celebrity Hair and Makeup Looks on the Red Carpet

66 of the Best After-Christmas Beauty Sales to Shop Now: Dermstore, Sephora, The Detox Market and More

So which type is safer and more effective? The answer is that it depends. Rather than the terms “mineral” and “chemical,” a more accurate way to think about sunscreen ingredients is “soluble” vs “insoluble.”

Soluble vs Insoluble UV Filters

• Soluble UV filters penetrate your skin, due to their small particle sizes, and absorb into your body. Two FDA studies have shown that soluble UV filters permeate into human blood, while other studies found detectable levels in human urine, serum and breast milk.^2,3 In 2016, a review of 85 scientific papers linked them to hormonal disruption, concluding that they “are generally involved in the disruption of the hypothalamic-pituitary-gonadal system.”⁴ Most—but not all—chemical sunscreen filters are soluble.
• Insoluble UV filters do not penetrate your skin, due to their large particle sizes, and therefore cannot absorb into your body and disrupt your hormones. These include the mineral sunscreen ingredients zinc oxide and titanium dioxide. Even at nanoparticle sizes as small as 30 nanometers, they have been shown not to penetrate beyond the outermost layer of skin.⁵ Certain chemical filters are also insoluble, however, most are not available in North America or only allowed in low concentrations.

Use this chart to check whether your sunscreen’s active ingredients are insoluble (safe) or soluble (to be avoided)^6,7:

^{* Banned in Canada and not “GRASE” (Generally Recognized As Safe and Effective) in the US.
† Unavailable in the US.
‡ Unavailable in the US and Canada.
§ Not GRASE in the US.}

As you can see, zinc oxide and titanium dioxide are the only two insoluble filters that are widely available in North America. In other jurisdictions, you have more choices—however, keep in mind that the safe insoluble chemical filters are almost always combined with the soluble ones that you want to avoid. “Good filters like bemotrizinol [Tinosorb S], bisoctrizole [Tinosorb M], ecamsule [Mexoryl SX], drometrizole [Mexoryl XL], and bisdisulizole [Neo Heliopan AP] are of limited availability in Canada and the USA, and even abroad are usually combined with the ‘undesirables’ and best avoided,” says Dr. Denis Dudley, co-founder of The Sunscreen Company.⁸

UVA vs UVB Protection

Besides safety, the other consideration when choosing a mineral or chemical sunscreen is how well it guards against UVA and UVB rays. 

Most chemical sunscreens are “UVB-biased.” In other words, they do a good job of filtering out the UVB rays that cause sunburn, but are inadequate against the more damaging UVA rays that trigger skin cancers and premature aging.⁹ This is particularly troubling because UVA accounts for up to 95% of the UV light that reaches our skin.¹⁰

The good news is that zinc oxide is not only safe, it’s also the single most effective UV filter in North America, providing extensive protection against both UVA and UVB.⁹

What SPF Should I Use?

Both the American Academy of Dermatology and the Canadian Dermatology Association recommend the use of sunscreens with an SPF of 30 or higher.¹¹

The problem is, SPF numbers on labels may not be accurate. Recent testing found that most sunscreens don’t meet their own protection claims, especially against UVA.¹ SPF readings can also be manipulated by adding certain “booster” ingredients and anti-redness agents.^12,13

Fortunately, if you know your sunscreen’s concentration of active ingredients, you can estimate its SPF number on your own using data from the industry’s sunscreen simulation tools.^14,15 

Use this chart to calculate the SPF number of your sunscreen:

So for every 1% of each active ingredient, you get a certain amount of SPF units. As you can see, 1% zinc oxide gives you a maximum of 1.6 SPF units, while 1% titanium dioxide gives you 2.6 SPF units. 

Let’s say you have a formula with 20% zinc oxide. That works out to SPF 32—an ideal SPF number. A formula with 15% zinc oxide and 5% titanium dioxide would be SPF 37.

How Much Zinc Oxide Should Be in a Sunscreen?

We’ve established that zinc oxide is the best UV filter available to us here in North America. Is there a certain minimum percentage to look for?

Yes. “For the North American consumer, it comes down to zinc oxide at a concentration of at least 15% as the best filter to protect against UVA,” says Dr. Sharyn Laughlin.

That means you’ve got two options:

• 20-25% zinc oxide: Since zinc oxide gives you extensive protection against UVA and UVB, it can be the sole active ingredient in your sunscreen. For SPF 30 protection, look for at least 20%, up to the maximum allowable concentration of 25%.
• 15-20% zinc oxide + >5% titanium dioxide: Alternatively, you can use formulas that contain both zinc oxide and titanium dioxide. To get SPF 30 and adequate UVA protection, you’ll need at least 15% zinc oxide with at least 5% titanium dioxide.

Avoid sunscreens that have less than 15% zinc oxide, or sunscreens that only contain titanium dioxide (which is primarily a UVB filter). They won’t give you enough protection against UVA.

What Are SPF Booster Ingredients?

Butyloctyl salicylate and tridecyl salicylate are two ingredients that you may want to avoid, known as “SPF boosters.” Some brands include them in their sunscreen formulas because they boost the SPF rating to get a higher number.¹²

Not only do they create an artificially higher SPF, they’re also being used in high concentrations, which may be unsafe. Both are modified forms of octisalate, which is a soluble chemical UV filter.¹⁶ They’re structurally similar, with a low molecular weight, and they can absorb into the bloodstream in the same way. 

“In addition to falsely raising the SPF as the others do, any salicylate will reach blood, cross the placenta, and like aspirin should be avoided in pregnancy,” says Dr. Dudley. “They are just as harmful to humans and the environment as homosalate and octisalate.”¹⁷

What Are PUFAs in Sunscreen?

Polyunsaturated fatty acids (PUFAs) are volatile, unstable fatty acids that are highly susceptible to oxidation in the presence of heat and light. When PUFAs oxidize, they generate free radicals, which are a major cause of skin aging and cellular damage.^18,19

You can limit exposure to PUFAs by choosing a sunscreen that is either oil-free or low in oils that have a polyunsaturated fatty acid profile. I avoid products with PUFA-based oils in the first five ingredients, which typically represent about 80% of the formula. 

If you’re not sure whether an oil has a polyunsaturated fatty acid profile, just google “[oil name] fatty acid profile” and it should come up.

Is Fragrance in Sunscreen Bad?

Fragrance compounds, whether synthetic or natural, are the most common trigger for irritations from personal care products.²⁰ If possible, go for either fragrance-free formulas or products that list fragrance at the end of their ingredients lists.

Is Silicone in Sunscreen Bad?

Although silicones are considered safe, you should know that they don’t actually moisturize.²¹ Instead, they create “slip” and a smooth finish by forming a film on top of your skin. Unfortunately, this film can trap pore-clogging ingredients, leading to breakouts if you are acne-prone. Silicone-based products are also more likely to cause pilling when layered. Personally, I look for sunscreens without silicones in the first five ingredients.

Does Sunscreen Contain Comedogenic Ingredients?

If you have acne-prone skin, it’s important to avoid comedogenic ingredients in all your beauty products, and sunscreen is no exception. Unfortunately, sunscreen is one of the products that is most likely to contain pore-clogging substances—even if it’s labelled as “non-comedogenic.”

Since there are dozens of potentially comedogenic ingredients, your best bet is to paste your sunscreen’s ingredients list into a “pore clogger checker.” (I like the ones by Biba de Sousa and Sofie Pavitt, who are both estheticians.) According to Dr. Olga Bunimovich, it’s the first seven ingredients that are key. “If it’s not within the first seven ingredients, then it’s most likely not going to be a problem.”²²

Conclusion + Further Reading

Clearly, there’s more to finding a good sunscreen than just figuring out whether it’s mineral vs chemical.

You also need to ensure that it contains the right ingredients, in the right concentrations, to shield you from UVA and UVB—especially UVA, since it’s the most damaging. 

With this guide to choosing a sunscreen, you’ll be able to do just that. Now you know what to look for on labels to find a truly broad-spectrum formula that will deliver the safest, most effective protection for your skin.