The Smart Girl’s Definitive Guide to Sunscreen Ingredients
Slather up, ladies! A cosmetic chemist’s guide to the most underrated and often overlooked sunscreen ingredients. Plus, the sunscreens I’m obsessed with this summer.
Smart girl summer is in full swing. Thank you to Alexis for officially declaring it!
Based on my Substack feed I have learned that, between my penchant for keeping my nails short and bare and my preference for coffee with just a splash of whole milk, I can include myself in the Hot Girl Club.
I recognize that declaring yourself is pas cool, but a girl’s gotta be her own advocate.
I think my strongest punch on my club card is my nerdiest habit/skill/party trick: my ability to read cosmetics labels ingredient by ingredient.
I recently went to the wedding of a good friend of mine. His roommates from years ago were there. I recognized them but couldn’t recall their names. I was ready to reintroduce myself—assuming they had no idea who I was—when one of them enthusiastically approached: “you’re that girl at our party that one time that taught us about skincare and why we should all be using niacinamide.” Yep, that’s me.
I’m 9 years into my career in beauty. I’ve learned a lot, but have a lot more to learn. My particular strength is ingredient list auditing. That’s being nice. It’s more like ingredient list hacking. I go ingredient by ingredient to rip formulas apart, identify their core elements, reveal their marketing fluff, and asses their true value. Read: Should I buy it or not?
The party trick part: I can do it live, no Google, no prep work, just straight from the hip INCI recital.
(The trick: I haven’t actually memorized all INCIs; if I don’t know something from experience I can make a good-enough guess on its function based in the context of the full formula, and the nomenclature rules of chemistry.)
Anyways, cool/hot/smart girls wear sunscreen. And they know their sunscreen ingredients, and how to read ingredient labels.
I took a cold hard look at all the trending sunscreens out there, ripped apart their ingredient lists, and decided which formulas I’m keeping with me all summer long.
Here’s my definitive list of sunscreen ingredients I think you should look for this summer—in a cool sense, not in an avoid sense. You’ll never catch me bad mouthing an ingredient based on its “clean” EWG score. I’m a science girylpop at heart. Plus, the top 7 sunscreens for smart girl summer.
My favorite sunscreen ingredients:
Aluminum Starch Octenylsuccinate
Ammonium Acryloyldimethyltaurate/VP Copolymer
Butyloctyl Salicylate
C12-15 Alkyl Benzoate
Dibutyl Adipate
Jojoba (as Jojoba Oil, Hydrolyzed Jojoba Esters, or Jojoba Esters)
Niacinamide
Polyhydroxystearic Acid
Shea Butter
Zinc Oxide
All of these ingredients are found in my favorite sunscreens this summer:
Best Overall: Trader Joe’s: Zinc Oxide Sunscreen Lotion SPF 40 $9.99
Best Face Sunscreen: Beauty of Joseon: Relief Sun Aqua Fresh: Rice + B5 SPF 50+ PA++++ $19.95
Best Drugstore Face Sunscreen: Neutrogena: Ultra Sheer Dry-Touch Sunscreen SPF 55 $14.49
Best Body Sunscreen: Vacation Inc.: Classic Lotion SPF 50 $15
Best Face Serum: Beauty of Joseon: Ginseng Sun Serum $21
Best Sport Sunscreen: Up & Up: SPF 30 Sport Sunscreen Lotion $5.89
Most Fun Sunscreen: Vacation Inc.: Shake Shake SPF 50 $27
Each of these formulas features at least two of my favorite ingredients. I’ll first run through a quick definition of each of my favorite ingredients and how they’re often used in sunscreen formulas. After that, I’ll give ya a quick rundown of each formula and why they made it to my favorites this summer.
My Favorite Sunscreen Ingredients
Aluminum Starch Octenylsuccinate
An unsung and often overlooked ingredient, Aluminum Starch Octenylsuccinate is often indicator that the formula will not be too greasy at first touch, rub-in, or afterfeel. ASO is a starch, often used as a “softening” or “texturizing” agent. Read: it helps formulas feel smooth and soft as you rub it on your skin. It’s a fine white powder that’s really good at oil absorption, so that formulas feel dry-touch instead of greasy. In sunscreen, it can also help with the physical dispersion of the sunscreen actives, resulting in a more uniform spread and feel of the formula. Generally speaking, a more uniform spread of the formula means more uniform sun protection; more uniform spreading also often means boosted UV protection. As a consequence of oil absorption, it can also act as a mild thickener, helping the formula not only feel good as you rub it in, but stay in place once it’s there as a breathable film over the skin. That’s why you’ll often see this ingredient in sport or sweat-resistant formulas.
Find it in:
Ammonium Acryloyldimethyltaurate/VP Copolymer
Just like ASO starch, Ammonium Acryloyldimethyltaurate/VP Copolymer is an unsung background player. Due to it’s large molecular structure (it’s a high-molecular polymer, to be more exact), it can play multiple roles at once: it can be a film-former, thickener, stabilizer, emulsifier aid, etc. It gets in between stuff and acts like a scaffold or matrix around and within which other skincare ingredients sit. In sunscreens, it’s often used primarily as an SPF booster, given its ability to help disperse sunscreen actives, and keep them uniformly distributed in a breathable, lightweight film on the skin’s surface. It can also help create rub-in with minimal or no streaks, and can improve water resistance by forming a soft but flexible film. That’s why you’ll also often find this ingredient in primers or lightweight moisturizers.
Find it in:
Trader Joe’s: Zinc Oxide Sunscreen Lotion SPF 40
Butyloctyl Salicylate
Butyloctyl Salicylate is a go-to cheerleader of sunscreen actives, if you will. Not only will it help solubilize and disperse the sunscreen actives within the formula, but it can also help boost the UV protective properties of those sunscreen actives. I realize that most of this list of sunscreen ingredients are pigment dispersers in some form, but that’s the secret key to good spread and uniform protection! BS in particular is common because of its multiple functions within sunscreen formulas. Arguably the most important and unique to BS is its ability to help boost the formulas’s SPF protection: its chemical structure, in oversimplified terms, allows it be a supportive ingredient for the primary UV filters. It’s a photostabilizer, interacting with electrons in a way that allows the primary sunscreen actives to interact with sunlight, return to their ground or resting state, absorb more UV radiation, relax, absorb UV radiation, relax, etc., for more cycles than it could handle solo. In this way it can help slow photodegradation of the sunscreen actives, allowing the formula to work as it should for as long as possible. This is a brutal oversimplification, and makes me want to write a whole article about how sunscreens actually work, but suffice it to say that it’s an inactive UV absorber, compatible with both mineral and chemical systems. As a bonus, it’s also a really good solvent and emollient.
Find it in:
C12-15 Alkyl Benzoate
Another multi-functional active, C12-15 Alkyl Benzoate is a colorless to slightly yellow transparent liquid primarily used as a lightweight emollient or texturizer, helping formulas to feel softer. It is, you guessed it, another pigment disperser and carrier, increasing not just the feel but effectiveness of sunscreen formulas. As an ester it helps dissolve oil-soluble UV filters, and provides the finished formula with a silky yet dry feel where other oils might add a heaviness or greasiness.
Find it in:
Dibutyl Adipate
Dibutyl Adipate is often the key to creating formulas with super breathable and spreadable films. It’s a plasticizer, helping to decrease the drag, waxiness, or brittleness of otherwise stiff blends, and a solubilizer for some UV filters. It can often be used in place of silicones, due to its ability to create fast-spreading but super conditioning textures, without feeling too dry or powdery.
Find it in:
Jojoba (as Jojoba Oil, Hydrolyzed Jojoba Esters, or Jojoba Esters)
I wouldn’t normally lump these ingredients together, but I have spotted a trend of using Jojoba-derived ingredients as a way to make sunscreen feel more like skincare, and I’m here for it. These ingredients generally help establish super elegant spread and glide, especially in Zinc Oxide creams.
Find it in:
Zinc Oxide Sunscreen Lotion SPF 40
Niacinamide
If there’s one skincare ingredient I think everyone should know about, it’s Niacinamide. There are no magic wands in skincare, but from what I’ve picked up from derms and etsys, this is the one ingredient good for any skin type. I usually reserve it for use in face or body serums to help calm redness, soothe irritation, brighten skin tone, and/or even skin texture. You may (or should) be already getting your daily dose of Niacinamide from serums or moisturizers but, if not, having it in your sunscreen can be an added bonus. I wouldn’t rely on sunscreen to be your primary source of Niacinamide, but its almost always a nice touch in formulas boasting skin benefits beyond UVA-B protection.
Find it in:
Polyhydroxystearic Acid
I’ve talked a lot about pigment dispersers, but this one is my favorite. PHSA helps disperse Zinc Oxide evenly in formulas, allowing for even spread and better UV protection. It can also be used to fine tune viscosity, and can play a role in the final texture of the formula. At room temp its a white-yellowish soft wax, easily-enough incorporated into oil phases. It can also help reduce whitening and stickiness in formulas. Honestly, where there’s Zinc Oxide, there should be PHSA.
Find it in:
Trader Joe’s: Zinc Oxide Sunscreen Lotion SPF 40
Shea Butter
Like Jojoba, this callout is more for bonus skin benefit than anything else. The additional of shea butter tells me that the formulator cares about skin feel and skin health beyond the primary function of UV protection.
Find it in:
Zinc Oxide
I’m a mineral girl by default. Chemical sunscreens do not (always) deserve the bad rap they’ve been given. The classic four part mixture of Avobenzone + Homosalate + Octisalate + Octocrylene is perfectly great—and can be found in Target’s SPF 30 Sport Sunscreen Lotion, Neutrogena’s UltraSheer SPF 55, and Vacation’s Classic Lotion SPF 50. I just generally prefer Zinc Oxide, especially now that dispersion technologies have gotten to the point of easy rub-in and near-invisible finish.
Speaking as a chemist, I have no scientific basis on which to prefer Zinc Oxide over other SPF actives. If I write about an ingredient or raw material on this Substack I usually have a good reason, but I have to admit that choosing Zinc Oxide over other sunscreen filters is more of a vibe than anything else. The bias could stem from my undergraduate days; I enjoyed inorganic and physical chemistry way more than organic chemistry.
The nerdy nuance with Zinc Oxide comes with the average size of the pigment used. Non-nano is all the rage now, and is generally preferred by chemist and consumer alike. The “non-nano” label generally means that the mean particle size of each piece (for lack of a better word) of ZnO is >100 nm. Some formulas intentionally use a diverse mix of mean particle sizes, as particle size distribution has been shown to help boost broad-spectrum coverage. Some of the best formulas, in my opinion, employ this technique.
Even though Zinc Oxide is my favorite sunscreen protectant, only two of seven featured sunscreens use ZnO. It’s possible that that’s a consequence of my want to keep this list focused on the more generic and cheap formulas out there. Zinc Oxide sunscreens do tend to be a bit more expensive than their chemical filter cousins out there.
Find it in:
Trader Joe’s: Zinc Oxide Sunscreen Lotion SPF 40
My Favorite Sunscreens This Summer
Best Overall: Trader Joe’s: Zinc Oxide Sunscreen Lotion SPF 40
It may not be the best-smelling or most cosmetically-elegant, but it’s a crowd pleaser. You can throw this in your beach bag or pack it with the boat snackale box and anyone can use it. It’s best for body, but can be used on the face as well. A tad greasy, but certainly not the worst. Wins best overall for being a reliable stand-by.
IL: Zinc Oxide (20.5%) + Water (Aqua), Isopropyl Palmitate, Caprylic/Capric Triglyceride, Hydrogenated Methyl Abietate, Glycerin, Sorbitan Laurate, Octyldodecyl Citrate Crosspolymer, Polyhydroxystearic Acid, Simmondisa Chinensis (Jojoba) Seed Oil, Phenoxyethanol, Ammonium Acryloyldimethyltaurate/VP Copolymer, Sodium Stearoyl Glutamate, Methylcellulose, Sodium Lauryl Glucose Carboxylate, Polyglyceryl-4 Laurate, Lauryl Glucoside, Xanthan Gum, Dilauryl Citrate, Ethylhexylglycerin, Sodium Phytate, Leuconostoc/Radish Root Ferment Filtrate, Aloe Barbendensis Leaf Juice, Lonicera Japonica (Honeysuckle) Flower Extract, Lonicera Caprifolium (Honeysuckle) Flower Extract, Populus Tremuloides Bark Extract, Tocopherol, Glycine Soja (Soybean) Oil, Gluconolactone, Ginkgo Biloba Leaf Extract, Camellia Sinensis Leaf Extract, Bambusa Arundinacea Stem Extract
Best Face Sunscreen: Beauty of Joseon: Relief Sun Aqua Fresh: Rice + B5 SPF 50+ PA++++
I use this every morning, and often throw it in my bag for reapplication over the course of the day. I don’t even need a mirror for a freshen up; it blends in so lightly and quickly that it feels more like a refreshing moisturizer than anything else. Equally great for makeup-free or glam days.
IL: Water, Oryza Sativa (Rice) Seed Water, Dibutyl Adipate, Butyloctyl Salicylate, Ethylhexyl Triazone, Drometrizole Trisiloxane, Polyglyceryl-3 Distearate, Terephthalylidene Dicamphor Sulfonic Acid, Diethylamino Hydroxybenzoyl Hexyl Benzoate, Polymethylsilsesquioxane, Tromethamine, 1,2-Hexanediol, Panthenol, Pentylene Glycol, Glyceryl Stearate, Silica, Caprylyl Methicone, Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine, Propanediol, Potassium Cetyl Phosphate, Poly C10-30 Alkyl Acrylate, Methylpropanediol, Carbomer, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Ethylhexylglycerin, Xanthan Gum, Glycerin, Polyether-1, Avena Sativa (Oat) Kernel Extract, Cynara Scolymus (Artichoke) Leaf Extract, Polyquaternium-51, Camellia Sinensis Leaf Water, Hydrogenated Lecithin, Beta-Glucan, Biosaccharide Gum-1, Inositol, Tocopherol, Ferulic Acid, Oryza Sativa (Rice) Bran Oil, Citric Acid, Ceramide NP, Phytosphingosine, Sodium Hyaluronate, Rice Amino Acids, Rice sh-Oligopeptide-1
Best Drugstore Face Sunscreen: Neutrogena: Ultra Sheer Dry-Touch Sunscreen SPF 55
My go-to drugstore purchase (though that may change now that Vacation Inc. is sold at most CVS and Target locations). Great for beach days and camping trips.
IL: Avobenzone (3%), Homosalate (10%), Octisalate (5%), Octocrylene (10%) + Water, Styrene/Acrylates Copolymer, Silica, Dimethicone, Potassium Cetyl Phosphate, Benzyl Alcohol, Beeswax, Caprylyl Methicone, Glyceryl Stearate, PEG-100 Stearate, Cetyl Dimethicone, Caprylyl Glycol, Ethylhexylglycerin, Aluminum Starch Octenylsuccinate, Behenyl Alcohol, Acrylates/Dimethicone Copolymer, Xanthan Gum, Sodium Polyacrylate, Chlorphenesin, Dimethicone/PEG-10/15 Crosspolymer, Hydrolyzed Jojoba Esters, Fragrance, Disodium EDTA, Ethylhexyl Stearate, Tocopheryl Acetate, BHT, Trideceth-6, Jojoba Esters
Best Body Sunscreen: Vacation Inc.: Classic Lotion SPF 50
It’s just really good sunscreen. And it does smell as good as advertised, without being too overpowering.
IL: Avobenzone (2.8%), Homosalate (9.8%), Octisalate (4.9%), Octocrylene (9.5%) + Aloe Barbadensis (Aloe Vera) Leaf Juice, Butyloctyl Salicylate, Butyrospermum Parkii (Shea) Butter, Cetearyl Alcohol, Cocos Nucifera (Coconut) Oil, Dimethicone, Ethylhexyl Palmitate, Ethylhexylglycerin, Fragrance, Glycerin, Musa Paradisiaca (Banana) Fruit Extract, Niacinamide (Vitamin B3), Phenoxyethanol, Silica, Sodium Hyaluronate, Sodium Phytate, Sodium Polyacrylate, Sodium Stearoyl Glutamate, Tocopherol (Vitamin E), Trimethylpentanediol/Adipic Acid/Glycerin Crosspolymer, Water
Best Face Serum: Beauty of Joseon: Ginseng Sun Serum
If you’re turned off by white goops and creams, go with this lightweight serum instead. Great for daily wear under makeup.
IL: Water, Panax Ginseng Root Extract, Dibutyl Adipate, Diethylamino Hydroxybenzoyl Hexyl Benzoate, Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine, Alcohol, Acrylates Copolymer, Butyloctyl Salicylate, C12-15 Alkyl Benzoate, Ethylhexyl Triazone, Niacinamide, Phenethyl Benzoate, Panax Ginseng Berry Extract, Panax Ginseng Extract, Panax Ginseng Leaf/Stem Extract, Silica, Methylpropanediol, Olea Europaea (Olive) Fruit Oil, Amyris Balsamifera Bark Oil, Angelica Archangelica Root Oil, Citrus Aurantium, Amara (Bitter Orange) Leaf/Twig Oil, Ferula Galbaniflua (Galbanum) Resin Oil, Jasminum Officinale (Jasmine) Oil, Panax Ginseng Root, Extract, Isoamyl p-Methoxycinnamate, Polysilicone-15, Polymethylsilsesquioxane, 1,2-Hexanediol, Dibutyl Lauroyl Glutamide, Pentylene Glycol, Dibutyl Ethylhexanoyl Glutamide, Ammonium Acryloyldimethyltaurate/VP Copolymer, Sodium Acrylates Crosspolymer-2, Sodium Polyacryloyldimethyl Taurate, C30-45 Alkyldimethylsilyl Polypropylsilsesquioxane, Hydroxyacetophenone, Adenosine, Glycerin, Butylene Glycol, Ethyl Hexanediol, Tocopherol, Ethylhexylglycerin, Xanthan Gum, Disodium EDTA
Best Sport Sunscreen: Up & Up: SPF 30 Sport Sunscreen Lotion
I love a Target generic, and this no exception. Bang for your buck, and actually stays on. I slathered up with this stuff right before my hard run yesterday and my skin didn’t get all gross and gunky with sunscreen sweat, despite the 90 degree day and quick pace.
IL: Avobenzone (3.0%), Homosalate (8.0%), Octisalate (5.0%), Octocrylene (8.0%) + Aluminum Starch Octenylsuccinate, Aminomethyl Propanol, Benzyl Alcohol, Butyrospermum Parkii (Shea) Butter, Caprylyl Glycol, Carbomer, Dimethicone, Disodium EDTA, Ethylhexylglycerin, Persea Gratissima (Avocado) Oil, Phenoxyethanol, Polyethyloxazoline, Polyglyceryl-3 Distearate, Simmondsia Chinensis (Jojoba) Seed Oil, Sorbitan Isostearate, Sorbitol, Stearic Acid, Tocopherol, Tridecyl Salicylate, Water
Most Fun Sunscreen: Vacation Inc.: Shake Shake SPF 50
This formula may deserve its own full article. I love pretty much everything Vacation Inc. does, but this is a stroke of brillance: instead of fighting the separation and shake-before-use requirement that most brands fight, they leaned into it, turning the formula’s otherwise weakest quality into an engaging, defining characteristic. Brilliant.
IL: Zinc Oxide (20.5%) + Aloe Barbadensis (Aloe Vera) Leaf Juice, Butyloctyl Salicylate, Butyrospermum Parkii (Shea) Oil, C12-15 Alkyl Benzoate, Camellia Sinensis (White Tea) Leaf Extract, Caprylhydroxamic Acid, Caprylic/Capric Triglyceride, Carbomer, Ceramide AP, Ceramide EOP, Ceramide NP, Cholesterol, Cucumis Sativus (Cucumber) Fruit Extract, Dihydro Myrcenol, Diisostearoyl Polyglyceryl-3 Dimer Dilinoleate, Dimethicone, Ethylhexyl Methoxycrylene, Ethylhexyl Olivate, Ethylhexylglycerin, Ferulic Acid, Floralozone, Glycerin, Gossypium Herbaceum (Cotton) Seed Oil, Hexyl Cinnamic Aldehyde, Hyaluronic Acid, Isododecane, Magnesium Sulfate, Methyl Octyne Carbonate, Niacinamide (Vitamin B3), Passiflora Edulis (Passion Fruit) Seed Oil, Phenoxyethanol, Phytosphingosine, Polyglyceryl-3 Oleate, Polyglyceryl-4 Diisostearate/Polyhydroxystearate/Sebacate, Polyglyceryl-4 Isostearate, Polyhydroxystearic Acid, Scentenal, Sodium Benzoate, Sodium Gluconate, Sodium Lauroyl Lactylate, Squalane, sr-Hydrozoan Polypeptide-1, Tocopherol (Vitamin E), Triethoxycaprylylsilane, Undecavertol, Water, Xanthan Gum
As all derms, estys, and chemists say, the best sunscreen is the one you actually wear. I’m normally super picky about skincare, but when it comes to sunscreen I say go with what’s cheapest, funniest, and/or most convenient. Just make sure you use it daily and often. And one final note: you really don’t need Aloe extract or leaf juice in your sunscreen. It’s rarely used well, and even when it is, it is far better suited for leave-on moisturizing serums that have a chance to sink in (vs. sweat-off sunscreen). Better yet look for Niacinamide, Glycerin, Bisabolol, or Allantoin for after sun care. The only time Aloe Vera is really effective is when it’s straight from the plant.
Happy Smart Girl Summer! Go put on sunscreen!
Lizzy