What's inside
What's inside
Key Ingredients
Benefits
Concerns
Ingredients Side-by-side
Water
Skin ConditioningZinc Oxide
Cosmetic ColorantCyclohexasiloxane
EmollientButyloctyl Salicylate
Skin ConditioningPropylheptyl Caprylate
EmollientPropanediol
SolventDicaprylyl Carbonate
EmollientIsododecane
EmollientPolyglyceryl-3 Polydimethylsiloxyethyl Dimethicone
Skin ConditioningCaprylyl Methicone
Skin ConditioningSodium Hyaluronate
HumectantHyaluronic Acid
HumectantHydrolyzed Sodium Hyaluronate
Skin ConditioningHydrolyzed Hyaluronic Acid
HumectantSodium Acetylated Hyaluronate
HumectantSodium Hyaluronate Crosspolymer
HumectantPotassium Hyaluronate
Skin ConditioningDimethylsilanol Hyaluronate
HumectantHydroxypropyltrimonium Hyaluronate
Sodium Hyaluronate Dimethylsilanol
HumectantPanthenol
Skin ConditioningAllantoin
Skin ConditioningTrehalose
HumectantCeramide NP
Skin ConditioningHamamelis Virginiana Extract
AntiseborrhoeicPortulaca Oleracea Extract
Skin ConditioningAnthemis Nobilis Flower Extract
MaskingSimmondsia Chinensis Seed Oil
Emollient2,3-Butanediol
HumectantDisteardimonium Hectorite
StabilisingMagnesium Sulfate
Triethoxycaprylylsilane
Methyl Methacrylate Crosspolymer
Polyglyceryl-2 Dipolyhydroxystearate
Skin ConditioningLauryl Polyglyceryl-3 Polydimethylsiloxyethyl Dimethicone
Skin ConditioningGlyceryl Caprylate
EmollientCaprylyl Glycol
EmollientButylene Glycol
HumectantTocopherol
AntioxidantEthylhexylglycerin
Skin Conditioning1,2-Hexanediol
Skin ConditioningMelia Azadirachta Leaf Extract
Skin ConditioningMelia Azadirachta Flower Extract
Skin ConditioningCoccinia Indica Fruit Extract
Skin ConditioningSolanum Melongena Fruit Extract
Skin ConditioningAloe Barbadensis Flower Extract
EmollientCurcuma Longa Root Extract
MaskingCorallina Officinalis Extract
Skin ConditioningOcimum Sanctum Leaf Extract
Skin ConditioningCamellia Sinensis Leaf Extract
AntimicrobialMalachite Extract
AntioxidantWater, Zinc Oxide, Cyclohexasiloxane, Butyloctyl Salicylate, Propylheptyl Caprylate, Propanediol, Dicaprylyl Carbonate, Isododecane, Polyglyceryl-3 Polydimethylsiloxyethyl Dimethicone, Caprylyl Methicone, Sodium Hyaluronate, Hyaluronic Acid, Hydrolyzed Sodium Hyaluronate, Hydrolyzed Hyaluronic Acid, Sodium Acetylated Hyaluronate, Sodium Hyaluronate Crosspolymer, Potassium Hyaluronate, Dimethylsilanol Hyaluronate, Hydroxypropyltrimonium Hyaluronate, Sodium Hyaluronate Dimethylsilanol, Panthenol, Allantoin, Trehalose, Ceramide NP, Hamamelis Virginiana Extract, Portulaca Oleracea Extract, Anthemis Nobilis Flower Extract, Simmondsia Chinensis Seed Oil, 2,3-Butanediol, Disteardimonium Hectorite, Magnesium Sulfate, Triethoxycaprylylsilane, Methyl Methacrylate Crosspolymer, Polyglyceryl-2 Dipolyhydroxystearate, Lauryl Polyglyceryl-3 Polydimethylsiloxyethyl Dimethicone, Glyceryl Caprylate, Caprylyl Glycol, Butylene Glycol, Tocopherol, Ethylhexylglycerin, 1,2-Hexanediol, Melia Azadirachta Leaf Extract, Melia Azadirachta Flower Extract, Coccinia Indica Fruit Extract, Solanum Melongena Fruit Extract, Aloe Barbadensis Flower Extract, Curcuma Longa Root Extract, Corallina Officinalis Extract, Ocimum Sanctum Leaf Extract, Camellia Sinensis Leaf Extract, Malachite Extract
Water
Skin ConditioningZinc Oxide
Cosmetic ColorantButyloctyl Salicylate
Skin ConditioningPropylheptyl Caprylate
EmollientPropanediol
SolventC15-19 Alkane
SolventDisiloxane
Skin ConditioningIsododecane
EmollientCetyl Diglyceryl Tris(Trimethylsiloxy)Silylethyl Dimethicone
Emulsion StabilisingCaprylyl Methicone
Skin ConditioningIsopropyl Myristate
EmollientSodium Chloride
MaskingTriethylhexanoin
MaskingGlycerin
HumectantDisteardimonium Hectorite
StabilisingMethyl Methacrylate Crosspolymer
Polymethylsilsesquioxane
1,2-Hexanediol
Skin ConditioningTriethoxycaprylylsilane
Dipentaerythrityl Tri-Polyhydroxystearate
EmollientHouttuynia Cordata Extract
Skin ConditioningLauryl Dimethicone/Polyglycerin-3 Crosspolymer
CleansingPolyglyceryl-2 Dipolyhydroxystearate
Skin ConditioningPanthenol
Skin ConditioningCaprylyl Glycol
EmollientGlyceryl Caprylate
EmollientMelia Azadirachta Leaf Extract
Skin ConditioningMelia Azadirachta Flower Extract
Skin ConditioningButylene Glycol
HumectantCoccinia Indica Fruit Extract
Skin ConditioningAmber Powder
Dipropylene Glycol
HumectantSolanum Melongena Fruit Extract
Skin ConditioningCurcuma Longa Root Extract
MaskingOcimum Sanctum Leaf Extract
Skin ConditioningTocopherol
AntioxidantCorallina Officinalis Extract
Skin ConditioningMoringa Oleifera Seed Oil
EmollientSodium Citrate
BufferingLecithin
EmollientSodium Hyaluronate
HumectantAllantoin
Skin ConditioningDipotassium Glycyrrhizate
HumectantSodium PCA
HumectantArginine
MaskingCeramide NP
Skin ConditioningErythritol
HumectantAsiaticoside
AntioxidantMadecassic Acid
Skin ConditioningAsiatic Acid
Skin ConditioningCentella Asiatica Extract
CleansingPentylene Glycol
Skin ConditioningOctanediol
Water, Zinc Oxide, Butyloctyl Salicylate, Propylheptyl Caprylate, Propanediol, C15-19 Alkane, Disiloxane, Isododecane, Cetyl Diglyceryl Tris(Trimethylsiloxy)Silylethyl Dimethicone, Caprylyl Methicone, Isopropyl Myristate, Sodium Chloride, Triethylhexanoin, Glycerin, Disteardimonium Hectorite, Methyl Methacrylate Crosspolymer, Polymethylsilsesquioxane, 1,2-Hexanediol, Triethoxycaprylylsilane, Dipentaerythrityl Tri-Polyhydroxystearate, Houttuynia Cordata Extract, Lauryl Dimethicone/Polyglycerin-3 Crosspolymer, Polyglyceryl-2 Dipolyhydroxystearate, Panthenol, Caprylyl Glycol, Glyceryl Caprylate, Melia Azadirachta Leaf Extract, Melia Azadirachta Flower Extract, Butylene Glycol, Coccinia Indica Fruit Extract, Amber Powder, Dipropylene Glycol, Solanum Melongena Fruit Extract, Curcuma Longa Root Extract, Ocimum Sanctum Leaf Extract, Tocopherol, Corallina Officinalis Extract, Moringa Oleifera Seed Oil, Sodium Citrate, Lecithin, Sodium Hyaluronate, Allantoin, Dipotassium Glycyrrhizate, Sodium PCA, Arginine, Ceramide NP, Erythritol, Asiaticoside, Madecassic Acid, Asiatic Acid, Centella Asiatica Extract, Pentylene Glycol, Octanediol
Reviews
Ingredients Explained
These ingredients are found in both products.
Ingredients higher up in an ingredient list are typically present in a larger amount.
1,2-Hexanediol is a synthetic liquid and another multi-functional powerhouse.
It is a:
- Humectant, drawing moisture into the skin
- Emollient, helping to soften skin
- Solvent, dispersing and stabilizing formulas
- Preservative booster, enhancing the antimicrobial activity of other preservatives
Allantoin is a soothing ingredient known for its protective and moisturizing properties; it's basically a quiet workhorse ingredient you can find in a huge range of cosmetics.
Though it can be derived from the comfrey plant, allantoin is produced synthetically for cosmetic products to ensure purity.
Research shows it can encourage your skin cells to turn over and renew by stimulating keratinocyte and fibroblast proliferation.
It also has mild keratolytic properties to help loosen and shed dead skin cells without being harsh.
Studies also suggest allantoin can help calm inflammation by dialing down some of the chemical signals your skin sends out when it is irritated.
This ingredient is typically used in the 0.1-0.5% range, and the FDA recognizes it as a skin protectant in OTC products up to 2%.
Overall, allantoin is a wonderful addition to most routines; it is stable across a wide pH range (~4-8), works well with other ingredients, and is considered non-sensitizing/non-irritating.
Fun fact: Allantoin is naturally occurring in comfrey root, beets, chamomile, and wheat sprouts. Our bodies even produce it as a byproduct of uric acid metabolism.
Learn more about AllantoinButylene Glycol (or BG) is used within cosmetic products for a few different reasons:
Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.
Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.
Learn more about Butylene GlycolButyloctyl Salicylate is a chemical UV filter structurally similar to octisalate. It is a photostabilizer, SPF booster, emollient and solvent. This ingredient helps evenly spread out ingredients.
According to a manufacturer, it is suitable for pairing with micro Titanium Dioxide, Zinc Oxide, and pigments.
Photostabilizers help stabilize UV-filters and prevents them from degrading quickly.
Learn more about Butyloctyl SalicylateCaprylyl Glycol is a humectant, skin conditioner, emollient, and preservative booster derived from either caprylic acid or synthetically created.
Typical use levels vary from 0.3-1% as a preservative booster and go up to 2% to condition skin.
Because it is not a free-fatty acid, this ingredient is fungal acne safe (there's nothing for Malassezia to feed on).
Learn more about Caprylyl GlycolCaprylyl Methicone is a synthetic and lightweight silicone fluid. It gives products a silky, dry-touch finish without the heaviness of pure oils.
Though the EU CosIng Database lists this ingredient as a skin conditioner, it is also used for sensory reasons. It spreads easily, cuts greasiness, and reduces tackiness.
This ingredient is volatile which means it will mostly evaporate (but it evaporates slower than older cyclomethicones, like Cyclotetrasiloxane).
Typical concentration ranges from 1-30% depending on if it's being used to tweak the feel of a product or acting as the main emollient.
Learn more about Caprylyl MethiconeCeramide NP (formerly known as Ceramide 3) is one of the skin's naturally occurring lipids.
Since ceramides are the major lipid components of the skin, they are crucial for maintaining skin barrier and hydration. Ceramide NP most closely mirrors the dominant kind in human skin amongst ceramide subtypes.
This ceramide works by slotting into gaps within the stratum corneum's lipid matrix to limit trans-epidermal water loss (TEWL) and shield the skin against external irritants.
A study with 312 patients found that using a ceramide-containing routine for 4 weeks reduced the severity of atopic dermatitis by over 61%.
Another clinical study in subjects aged 60 and older found that a ceramide body wash and moisturizer improved skin dryness and itchy skin in 15 days.
Overall, ceramides are considered non-irritating and safety tests have found little to no observable adverse effects from using this ingredient.
Ceramide NP is usually sourced from plants (like soybean or rice bran), or produced synthetically.
Learn more about Ceramide NPCoccinia Indica Fruit Extract is also known as Ivy Gourd Fruit Extract. It has skin conditioning properties.
The fruit is rich in flavonoids, phenolic acids, terpenoids, and sterols that show antioxidant and anti-inflammatory effect in vitro. This is because the fruit contains a thick mucilage that forms a protective and soothing layer on the skin's surface.
The extract itself has demonstrated antioxidant, soothing, and potential anti-allergy properties.
Most of this research is done in vitro and dedicated clinical studies on topical application are still limited.
Learn more about Coccinia Indica Fruit ExtractCorallina Officinalis Extract is from the red seaweed, Corallina Officinalis. This seaweed is found all over the world but is most common in the rocky shores of Great Britain and Ireland.
Corallina Officinalis Extract contains antioxidant and emollient properties.
Extracted polysaccharides, galactose and xylose, in red algae showed antioxidant activity. Antioxidants help with anti-aging by neutralizing free-radical molecules. Free-radical molecules may damage your skin cells and DNA. Galactose is also a PHA.
Corallina Officinalis is structurally similar to coral due to its high calcium content.
Learn more about Corallina Officinalis ExtractCurcuma Longa Root Extract is from the spice, turmeric. Besides being a healthy and delicious spice, turmeric also has plenty of skincare benefits. It has anti-inflammatory, antioxidant, and anti-microbial properties.
Turmeric contains curcumin, an antioxidant. Antioxidants help neutralize unstable free-radical molecules. Free-radical molecules may damage your skin's cells and DNA. Curcumin may help with anti-aging.
Curcumin also has anti-inflammatory properties and can help soothe skin and reduce irritation. On top of that, curcumin has been shown to help prevent hyperpigmentation from sun damage.
The anti-microbial property of turmeric can make it effective in treating acne. This property has also been shown to help regulate the production of sebum.
Learn more about Curcuma Longa Root ExtractDisteardimonium Hectorite comes from the clay mineral named hectorite. It is used to add thickness to a product.
It can also help stabilize a product by helping to disperse other ingredients.
Hectorite is a rare, white clay mineral.
Learn more about Disteardimonium HectoriteGlyceryl Caprylate comes from glycerin and caprylic acid. It is an emollient, co-emulsifier, and preservative booster.
Its short C8 fatty acid chain makes it behave differently from its longer-chain emollient cousins like Glyceryl Stearate. It feels more lightweight, fast-absorbing, and silky instead of rich and waxy.
As a co-emulsifier, its "head" and "tail" sit at the oil-water interface. But overall, the short C8 tail and not being water soluble means it doesn't really have the muscle to emulsify a formula on its own. That's why you'll often see it paired with a primary emulsifier like Cetearyl Glucoside.
Interestingly, Glyceryl Caprylate acts as a preservative booster. This is because its fatty-acid backbone disrupts microbial lipid membranes. It shows excellent activity against bacteria and yeast but is weaker against mold.
Typical concentrations range from 0.5-1% and this ingredient is generally non-irritating.
Because this ingredient has a C8 fatty acid chain, it is outside the range that the Malassezia yeast metabolizes (making it fungal acne safe).
Learn more about Glyceryl CaprylateIsododecane is a fragrance, emollient, and solvent.
As an emollient, it helps your skin stay soft and hydrated. Emollients help trap moisture into your skin.
Isododecane's role as a solvent makes it a great texture enhancer. It spreads smoothly on skin and does not leave a sticky feeling behind. Isododecane also helps prevent color transfer in makeup products.
Isododecane is not absorbed into skin.
The chemical name for this ingredient is 2,2,4,6,6-PENTAMETHYLHEPTANE.
Learn more about IsododecaneMelia Azadirachta Flower Extract is from the Neem tree. Neem trees originate from India.
Melia Azadirachta Flower Extract contains antioxidants. Antioxidants help fight free-radicals. Free-radicals are molecules that may damage your skin cells, such as pollution.
The flowers of this tree are lilac colored.
Learn more about Melia Azadirachta Flower ExtractThis ingredient is also known as neem leaf extract. It contains natural compounds like nimbidin, quercetin, and other polyphenols that give it antibacterial, antifungal, and anti-inflammatory activity.
Lab studies have shown neem leaf extract can inhibit acne-related bacteria and help calm skin. Animal studies on wound gels using 1-3% neem leaf extract found it sped up healing without causing irritation.
A wound-healing study testing gels with the extract at 1%, 2%, and 3% concentrations and found none of them irritated the skin.
Most commercial products also use it in a similar low range (typically under 5%).
Allergy-wise, there are some case reports on neem oil causing allergic contact dermatitis so people with plant/botanical sensitivities may want to patch test first.
Learn more about Melia Azadirachta Leaf ExtractThis ingredient comes as a powder made up of small, porous, microbeads. It is used to add a silky feel to products and also helps absorb oil.
Ocimum Sanctum Leaf Extract comes from the Holy Basil plant. Holy Basil is native to India.
Holy Basil is rich in antioxidants due to its high romarinic acid, ferulic acid, and rutin content. This gives it skin brightening and soothing properties.
While Holy Basil has many claims to help fight acne, more research is needed.
One thing to note is the presence of tannins; tannins are naturally found in nature. However, this compound may be skin-sensitizing.
Learn more about Ocimum Sanctum Leaf ExtractPanthenol is a common ingredient that helps hydrate and soothe the skin. It is found naturally in our skin and hair.
There are two forms of panthenol: D and L.
D-panthenol is also known as dexpanthenol. Most cosmetics use dexpanthenol or a mixture of D and L-panthenol.
Panthenol is famous due to its ability to go deeper into the skin's layers. Using this ingredient has numerous pros (and no cons):
Like hyaluronic acid, panthenol is a humectant. Humectants are able to bind and hold large amounts of water to keep skin hydrated.
This ingredient works well for wound healing. It works by increasing tissue in the wound and helps close open wounds.
Once oxidized, panthenol converts to pantothenic acid. Panthothenic acid is found in all living cells.
This ingredient is also referred to as pro-vitamin B5.
Learn more about PanthenolPolyglyceryl-2 Dipolyhydroxystearate isn't fungal acne safe.
Propanediol is an all-star ingredient. It softens, hydrates, and smooths the skin.
It’s often used to:
Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.
Learn more about PropanediolWe don't have a description for Propylheptyl Caprylate yet.
Sodium Hyaluronate is the salt form of hyaluronic acid. It is a long sugar chain that is naturally found in your skin, joints, and connective tissue that maintains hydration and elasticity.
In skincare, it works as a humectant. It pulls water from the environment and deeper layers of skin and binds it to the surface.
Interestingly, the size of the molecule affects its behavior:
Some clinical evidence links low molecular weight versions to improved wrinkle depth, elasticity, anti-inflammatory effects, and barrier repair.
Many serums use a blend of both weights so you can get surface hydration plus longer-lasting and deeper effects.
You'll typically see concentrations between 0.1-2% for this ingredient.
Learn more about Sodium HyaluronateThis ingredient comes from eggplant (or aubergine). It has skin conditioning properties due to its abundance of antioxidants like Chlorogenic Acid, Caffeic Acid, and Nasunin.
Nasunin is the pigment concentrated in the purple peel and has demonstrated the abilityu to neutralize free radicals and bind excess iron in lab studies.
Lab studies have shown that eggplant extracts can lower oxidative stress and protect skin cell membranes from damage. A 2025 study found that specific compounds in eggplant (particularly a phenolamide called N-Trans-Feruloylputrescine) may support skin health by neutralizing 2-nonenal, a byproduct linked to aging skin.
Overall, this is a gentle, well-tolerated ingredient that adds a little extra antioxidant support to your routine.
Those with nighshade vegetable allergies (tomatoes, peppers, potatoes) should patch test as eggplant is part of the same family.
Learn more about Solanum Melongena Fruit ExtractTocopherol is a fat-soluble antioxidant known as Vitamin E.
You'll find this ingredient in the vast majority of skincare (for good reason). It works to neutralize free radicals, or unstable molecules generated by UV exposure, pollution, and other environmental stressors, before they can cause oxidative damage to your skin cells.
Topically applied tocopherol has been shown to protect against UV damage by ramping up the skin's own natural defense enzymes.
It also acts as a skin conditioning agent; some studies show that regular topical use can improve the skin's water-binding capacity over 2-4 weeks.
This ingredient is especially loved for being a team player. When combined with Vitamin C, the photoprotective effect of both ingredients roughly doubles and the combo also helps reduce UV-induced DNA damage.
This ingredient has some brightening potential but it's more of a prevention ingredient than spot-fader. Cell studies show it can slow down melanin production but it's worth noting that it's not the most powerful brightener out there.
In formulations, it also serves as a stabilizer that helps protect other oxidation-prone ingredients from degrading.
Concentrations usually range from 0.1-1% in most leave-on products.
Learn more about TocopherolTriethoxycaprylylsilane is a silicon-based surface modifier that makes sunscreens feel silky and makeup stay put.
Its main job is to coat mineral particles like titanium dioxide, zinc oxide, and color pigments in a thin, oily layer so they spread smoothly, don't clump, and stick to skin better.
This ingredient is typically used at low levels (up to 2.5% in eyeshadow and 1% in lipstick).
Learn more about TriethoxycaprylylsilaneWater. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.
So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.
You'll also recognize water as that liquid we all need to stay alive. If you see this, drink a glass of water. Remember to stay hydrated!
Learn more about WaterZinc Oxide (ZO) is a mineral broad-spectrum UV filter and the broadest-spectrum filter recognized by the FDA. It covers everything from UVB through to long-wave UVA.
On top of sun protection, it has skin protectant and skin-soothing properties too.
Here's a myth worth busting: mineral filters are usually described as working by "reflecting" or "bouncing" UV off your skin.
That's mostly not true: when researchers actually measured it, ZO and Titanium Dioxide reflect only about 4-5% of UV (less than SPF 2 worth of protection).
The vast majority of the work (~95%) is done by absorption, similar to chemical UV filters. ZO is a semiconductor that absorbs UV photos through its energy band gap.
So the old "physical blocker vs. chemical absorber" framing is really an oversimplification.
Zinc Oxide is one of the most effective broad-spectrum UV filters out there. It protects across UVB, UVA2, and UVA1 with a flat, even absorption curve across the whole UVA-UVB range.
That uniform UVA coverage is its standout feature; titanium dioxide skews more toward UVB as its particle size drops so ZO gives more consistent and extended UVA protection.
It's also very photostable. As an inorganic oxide, ZO doesn't break down in sunlight the way some organic filters can, so it holds up over a day of wear.
This ingredient is gentle and soothing, making it go-to for sunscreens aimed at sensitive skin, rosacea, or ecezma-prone skin, babies, and children.
It's also unlikely to cause the "eye sting" that some sunscreen ingredients are known for, and regulatory agencies broadly consider it non-toxic and safe for topical use.
Beyond sun protection, ZO is also a recognized OTC skin protectant. It forms a breathable barrier that shields skin from moisture and irritation while supporting healing. This is why you'll see it as a classic active in diaper rash creams.
The only downside to ZO is that it can leave a visible white cast, especially on deeper skin tones. This is the main reason mineral sunscreens have historically felt less cosmetically elegant than chemical or hybrid formulas.
Zinc Oxide comes in both non-nano and nano forms. The dividing line is 100nm and anything under is classified as a nanomaterial by the EU.
The nano version scatters less visible light which cuts down white case and gives a lighter, more wearable texture.
Another thing worth understanding about formulation:
Uncoated ZO has some inherent photocatalytic activity. This just means it can generate reactive oxygen species under UV. It's exactly why cosmetic-grade ZO is almost always surface-coated; this coating suppresses that reactivity and improves how the powder disperses and feels.
A well-formulated coated ZO largely sidesteps this issue.
Zinc Oxide is commonly used anywhere from 10% up to the regulatory maximum in sunscreens (25%).
Mineral-only broad-spectrum products often land in the 15-25% range to hit higher SPF and UVA values. Keep in mind SPF performance depends heavily on particle size, dispersion, and the rest of the formula, and not just the percentage.
As an OTC skin protectant like diaper creams, ZO typically runs higher at roughly 10-40%.
This ingredient is generally easy to work with and doesn't photodegrade.
The only thing to know is that uncoated ZO can be a bit reactive in a formula.
Under UV, it can break down sensitive ingredients like other actives or UV filters. This is another reason coated versions are standard. ZO can also react with very acidic ingredients or throw off stability of some creams. A good formula will get around this with the right coatings and dispersion.
The EU's Scientific Committee on Consumer Safety has concluded that ZO nanoparticles "can be considered to not pose any risk of adverse effects in humans after application on healthy, intact or sunburnt skin".
You might hear that ZO is "toxic"; this is because an in-vitro (test tube) study suggested micronized ZO had potential phototoxicity. In vivo (human) investigations have disputed this and the results have come back reassuring.
So does ZO penetrate skin? The short answer is no, not in any way that matters.
The most relevant evidence comes from real-world human studies: in one, volunteers applied ZO nanoparticle sunscreen hourly for six hours and daily for five days. The advanced imaging showed the particles stayed on the surface and never reached the living epidermis, and no cellular toxicity was found.
Other in-vivo and ex-vivo work agree; ZO nanoparticles don't cross the stratum corneum, even on flexed, massaged, or barrier-impaired skin.
A small amount of solubilized zinc ions can dissolve off the particles and enter the upper skin. But the quantities are tiny compared to the zinc already naturally present in your body, and studies haven't found this to cause local toxicity.
The sunscreen bans you've heard of (like Hawaii's) are aimed at two chemical filters, Oxybenzone and Octinoxate. ZO itself it not banned and is often recommended instead.
So far, there's no solid evidence that any form of ZO harms reefs. It is an ongoing and active area of study, and worth keeping an eye on.
If you're traveling somewhere with these rules, a non-nano mineral sunscreen is the safe bet.
Learn more about Zinc Oxide