Shiseido Ultimate Sun Protector Lotion SPF 50+ Versus Estée Lauder Perfectionist Pro Multi-Defense Aqua UV Gel SPF 50

Studies show green tea extract and its catechins (like epigallocatechin gallate (EGCG)) help your skin cells product energy more efficiently and reducing the number of free-radicals that can damage your skin from the inside.

In lab-grown skin models, this translated to younger, healthier, and stronger skin.

There's also good sun protection data; researchers saw less DNA damage and redness on human skin when green tea was applied before UVB exposure. And the more they applied, the better the protection.

Needless to say, this ingredient shouldn't replace your sunscreen. But it is a great supportive ingredient that you can already find in many sunscreens and antioxidant serums.

A 2009 study found a 2% green tea lotion was effective for mild-to-moderate acne thanks to its anti-inflammatory and mild antimicrobial activity.

The quality of the extract matters a lot here:

Good extracts contain 50-90% catechins while lower quality ones are mostly there for marketing. We recommend reaching out to the brand if you have questions about the quality or source of their ingredients.

Human Repeated Insult Patch Testing showed no irritation or sensitization at use concentrations (0.86% in leave-on products and up to 30% as leaf water).

Typical use concentrations range from 0.5-5%, but can go up to 10% depending on how firm the gel is.

Because it's an ester built on a fatty acid, it may not be fungal acne safe.

You'll often see it paired with other UV filters to boost overall SPF because octisalate is a fairly week filter on its own.

The reason you'll see it so often is because it can help solubilize and stabilize the trickier filters like oxybenzone and avobenzone.

Unlike these filters, octisalate has pretty good photostability and doesn't create skin-damaging free radicals when exposed to sunlight.

The fatty-alcohol part of the molecule also gives it a light, emollient feel so it doubles as a nice texture enhancer.

Usage levels vary around the world:

Safety-wise, this ingredient has a pretty reassuring track record. The EU's Scientific Committee on Consumer Products (SCCP) found very low skin penetration in human skin tests and negative results for irritation, phototoxicity, and photoallergy.

The real-world allergy risk is pretty low too; a 2012 European study of 1,031 people recorded only 2 reactions to it (a rate of 0.19%).

You might have seen scary headlines about sunscreen getting into your blood.

In 2019, the FDA found that several chemical filters can absorb through the skin and show up in the bloodstream at small but measurable levels.

Here's the important part: these tiny levels are just a cutoff the FDA uses to decide which ingredients need more testing and doesn't mean anything harmful was found.

The researchers were clear that the results are no reason to stop wearing sunscreen.

Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.

Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.

This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.

Just know very high concentrations (>40%) can feel tacky in low humidity.

Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.

It's actually so reliable that formulators often pair it with shakier ingredients like oxybenzone and avobenzone. Formulators also use it to help dissolve the other UV filters into the oil phase.

One thing to keep in mind: "stable" isn't the same as "strong". On its own, homosalate is actually a pretty weak UV filter so it's better off as a helpful team player that helps boost overall SPF protection.

The safety picture is a bit nuanced but not scary.

This ingredient has a long track record of being gentle and regulators agree it isn't an irritant; EU's Scientific Committee on Consumer Safety found that homosalate is not considered a skin irritant and doesn't raise eye-irritation flags either.

There's talk about homosalate because your skin absorbs a little bit of it into your bloodstream. A 2020 FDA-backed study found homosalate showed up in people's blood levels at the level where the FDA decides to double check.

The EU's Scientific Committee on Consumer Safety (SCCS) also found small amounts in blood and breast milk. They estimated that about 5% of what you apply gets absorbed through the skin.

Due to the debate about whether it might mess with hormones, the SCCS recommended a maximum limit of 0.5% in most products of 7.3% in face creams/pump sprays.

One important thing to keep in mind: in the US, Homosalate is currently labeled "non-GRASE" by the FDA. This sounds alarming but really just means the FDA wants more data to confirm it's safe. It's not confidently saying this ingredient is harmful.

As of now, homosalate is still completely legal and widely used while that research gets done.

The current maximum limits are:

This ingredient is commonly used to enhance both UVB and UVA protection due to its unique property in stabilizing avobenzone. It also pulls double duty by boosting water resistance and giving formulas a smooth, spreadable feel.

The EU's Scientific Committee on Consumer Safety (SCCS) has deemed octocrylene to be safe as a UV-filter at concentrations up to 10% (capped at 9% in propellant sprays). The US also permits it up to 10%.

Two things worth knowing:

You'll usually see this ingredient used in concentrations between 2-10% (higher amounts when used as a stabilizer for avobenzone).

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!