Ulta Waterproof Eye & Lip Makeup Remover

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.

On a cellular level, it disrupts the cell membranes of microbes by poking holes that make the cell leak. This shuts down the chemical reactions the microbe needs to make energy so it can no longer survive.

Another perk of this ingredient is that it stays functional across a wide pH range (3-10).

You'll often see it paired with boosters like Ethylhexylglycerin; one study showed that a 1:9 ratio of Ethylhexylglycerin to Phenoxyethanol damages bacterial membranes as effectively as doubling the Phenoxyethanol concentration on its own.

Typical use concentrations range from 0.3-1% depending on the formula, and this ingredient is capped at 1% int the EU.

Safety-wise, the fear mongering does not hold up to the evidence. The EU's Scientific Committee on Consumer Safety and FDA consider it safe as a preservative at up to 1%, including for children of all ages.

Adverse systemic effects only showed up in animal studies at exposures roughly 200x higher than what people get from cosmetics. And despite its very widespread use, this ingredient is a rare sensitizer and allergic reactions are uncommon.

You might see people debate whether Sodium Chloride is comedogenic, but there actually haven't been any comedogenic tests done on it. Either way, the overall formulation of a product matters a lot more than any single ingredient.

You might see this ingredient used in scrubs as a primary exfoliating ingredient.

On top of that, this ingredient can counteract the effects of hard water by binding to the minerals in it.

One thing worth knowing is that Disodium EDTA has been shown to be a mild penetration enhancer. It can help other ingredients absorb into skin more effectively which can be a double-edged sword (great for actives, but can also make the active too strong if you have sensitive skin).

Clinical patch testing showed no significant skin irritation at typical use concentrations and minimal dermal absorption.

You'll most likely see this ingredient near the end of an ingredient list. It's typically found in concentrations less than 1%.

It also contains sugars in the form of monosaccharides and polysaccharides, folic acid, choline, many common minerals such as calcium, 12 anthraquinones, fatty acids, amino acids, and Vitamin B12.

Aloe is known to be anti-inflammatory, moisturizing, antiseptic, and healing.

Aloe should not replace your sunscreen, as it does not offer UV protection.

That's why you'll spot it in a variety of products from sunscreens to clear-packaged serums where it protects dyes, fragrances, and other actives from degrading.

As a UV filter, it is fairly weak on its own. This is why it's almost always paired with stronger UV filters to build up SPF.

On the regulatory side, this ingredient is well-studied and broadly considered safe as used.

The EU's Scientific Committee on Consumer Safety reviewed it (and the endocrine-disruption questions that had been raised) and concluded it's safe as a UV filter up to 5%.

The US and Canada allow up to 10% and the CIR Expert Panel has found benzophenones safe at cosmetic-use levels with low skin penetration.

The only thing worth flagging for is contact allergy:

Benzophenone-4 stands out among UV filters as a frequent trigger or allergic and photoallergic contact dermatitis. A 2007 study in Contact Dermatitis even called it an "emerging allergen" so a small subset of people may get redness or irritation from it.

They contain shikimate dehydrigenase, an enzyme shown to help reduce inflammation and soothe the skin.

The amino acids found in cucumbers help nourish our skin's natural acid mantle (it's an important part of our skin barrier). This slightly acidic film acts as a barrier to protect us from bacteria, viruses, and other contaminants.

Unless you have an allergy to cucumbers, this is generally a non-irritating ingredient.

Fun fact: Cucumis Sativus is native to South Asia and can now be found on every continent.

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.

Industry-reported use ranges from 8% in rinse-off products and 2% in leave-on formulations.

This dye is commonly used in foods, approved by both the FDA and EFSA.

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.