Vichy Capital Soliel SPF 50+ Fresh Protective Milk (Face & Body) Versus La Roche-Posay Anthelios Hydrating Lotion SPF 50+

Because it is not a free-fatty acid, this ingredient is fungal acne safe (there's nothing for Malassezia to feed on).

Formulators love it for its stability; its ability to filter UV stays practically unchanged even under intense radiation and it can also help boost the photostability of less stable filters like avobenzone.

It's also a great pick for water resistant products because it's insoluble in water and has a good affinity for keratin.

Because it's a big, heavy molecule, the European Scientific Committee has found to to have very low dermal penetration and negative results for allergenicity.

In vitro testing also showed a low absorption rate and clean results on irritation.

Typical use levels are 1-5% with 5% being the maximum in the EU, Japan, and other markets that allow it. However, this ingredient is not approved yet in the US or Canada.

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.

Typical usage concentrations range from 1-5%.

Human testing shows it's non-irritating and non-sensitizing, and the EU Scientific Committee on Consumer Safety (SCCS) has cleared it at very high levels (79% in leave-on products).

The one thing worth knowing about its comedogenic score of 3-4 is to keep it in perspective: these ratings come from old rabbit-ear tests using 100% of pure ingredient and doesn't reflect how it behaves at low levels in a finished product.

Because it is an ester of palmitic acid (C16), it falls into the range that the Malassezia yeast can feed on and is considered not fungal acne safe.

This peak absorption happens to be the exact type of UVA light that sinks deepest into skin and does the most to cause aging and dark spots.

Ecamsule works by soaking up UV rays and turning them into a tiny bit of harmless heat. The molecule basically flips, releases that energy as heat, then snaps back to its original shape and does it all over again. This is also why it's so stable in sunlight and doesn't break down or wear out the way some filters do.

The clinical backing for this ingredient is solid as well:

A large 2008 review by Fourtanier & colleagues (2008) pulled together human trials showing ecamsule-containing sunscreens prevented UV-induced pigmentation, DNA damage, and signs of aging.

That built on earlier work by Seite et al. (1998) that found it protected skin from repeated low-level UVA exposure. And a controlled study by DeLeo et al. (2009) showed that even an SPF 40 cream with ecamsule helped prevent sun-triggered rash even under the real sun.

On concentrations:

Because this ingredient is an acid, it has to be neutralized so it doesn't tank the product's pH.

Safety-wise, it's pretty well tolerated. There are some rare cases of mild irritation mostly in people with sensitivities towards camphor derivatives.

A 2019 FDA study found that volunteers who slathered on sunscreen heavily for several days had tiny amounts of ecamsule show up in their blood. This was slightly above the level at which the FDA asks for extra safety testing; this just means the FDA wants more safety studies done and not evidence that anything harmful actually happens. No problems were found and dermatologists still recommend using sunscreen.

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.

PH adjusters are common in cosmetic products. The pH of a product can affect the effectiveness of other ingredients. A product with a high pH may also irritate the skin.

If you are looking for the tea leaf ingredient, click here.

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!

Xanthan gum is a pretty common and great ingredient. It is a natural, non-toxic, non-irritating ingredient that is also commonly used in food products.