Laura Geller Spackle Skin Perfecting Primer

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.

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.

The CIR Expert Panel has confirmed this ingredient to be nontoxic and clinical studies show no sensitization at cosmetic use concentrations.

True allergic reactions are quite rare: a 15-year retrospective study of 6,751 patients found only 0.31% had a positive reaction (and less than half were considered clinically relevant).

It seemed that when sensitization does occur, it's most commonly linked to topical medication (like corticosteroids) and not cosmetics. Allergic contact dermatitis also appears largely limited to individuals with underlying skin conditions.

Overall, propylene glycol is a well-studied ingredient that most people can tolerate without issue.

Is it bad for your skin?

The answer comes down to concentration. Patch and wash studies have found highly concentrated alcohol-based hand rubs (60-100%) cause less barrier disruption than washing with a basic detergent like SLS. The only measurable effect in these studies was a temporary dip in skin hydration.

Concentrations below 12-15% in leave-on cosmetics is generally well-tolerated. Concentrations above start to see increased transepidermal water loss (TEWL) and reduced hydration.

In concentrations about 58%, it creates temporary channels in your skin's lipid layers to become more permeable and allow other ingredients to slip through easily.

This ingredient can be up to 80% of the formula in alcohol-based perfumes.

Overall, this ingredient is probably harmless if found lower down an ingredients list but worth side-eyeing if it's high up (especially if your barrier is already struggling).

Alcohol can worsen dry skin, eczema, and oily skin, especially at higher concentrations. This is because it can increase transepidermal water loss and decrease hydration to disrupt the skin barrier.

According to the National Rosacea Society based in the US, you should be mindful of products with these alcohols in the top half of ingredients.

True allergic contact dermatitis to ethanol is uncommon, but be sure to patch test if you have dry or sensitive skin.

Basically, Peg-60 Hydrogenated Castor Oil helps hold ingredients together.

Your skin has a natural pH and acid mantle. This acid mantle helps prevent harmful bacteria from breaking through. The acid mantle also helps keep your skin hydrated.

"Alkaline" refers to a high pH level. A low pH level would be considered acidic.

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.

A study from 2021 found this ingredient to inhibit melanin production. An animal study found plum blossom to help increase collagen production.

Papaya is also a rich source of antioxidants. Antioxidants protect your skin against damage from free-radical molecules. This may help protect against signs of aging. One antioxidant present in papayas is lycopene.

Papaya also contains Vitamin A, also known as retinol.

While papaya is used as an ingredient to help lighten skin, research is limited on this.

The seeds of papaya have been found to have anti-fungal activity.

However, this exfoliating effect only happens at high concentrations (20%) which can be hard to find in cosmetic products.

Due to this, citric acid is usually included in small amounts as a pH adjuster. This helps keep products slightly more acidic and compatible with skin's natural pH.

In skincare formulas, citric acid can:

While it can provide some skin benefits, research shows lactic acid and glycolic acid are generally more effective and less irritating exfoliants.

Most citric acid used in skincare today is made by fermenting sugars (usually from molasses). This synthetic version is identical to the natural citrus form but easier to stabilize and use in formulations.

Read more about some other popular AHA's here:

Potassium Sorbate, another commonly-used preservative, is the potassium salt of Sorbic Acid.

Sorbic Acid may worsen eczema. We recommend speaking with a professional if you have any concerns.

Potassium sorbate and sorbic acid can be found in baked goods, cheeses, dried meats, dried fruit, ice cream, pickles, wine, yogurt, and more.

Both potassium sorbate and sorbic acid can be found in baked goods, cheeses, dried meats, dried fruit, ice cream, pickles, wine, yogurt, and more.

You'll often find this ingredient used with other preservatives.

The FDA requires batch-to-batch certification for this ingredient that is held to a pretty rigorous standard. That means the CI 17200 in your cosmetics has been tested and approved before it ever reaches you.

Contact allergy to cosmetic-grade dyes used at low concentrations are uncommon but has been documented before.

This ingredient also goes by the name D&C RED NO. 33.

CI 17200 has a comedogenic rating of 1 and an irritancy rating of 2 on a scale of 0-5. This is based on peer-reviewed research from the man who invented the comedogenic scale.

A 1 on the comedogenic scale is about as low as it gets without being a flat zero, and makes sense for CI 17200.

It's a water-soluble dye used at very small concentrations (typically 0.001-0.1%), so it dissolves into the water phase of a formula rather than sitting on your skin the way an oil or wax would.

The irritancy rating of 2 reflects that, like most synthetic dyes, there's a small possibility of mild irritation ( particularly for people with existing dye sensitivities).

For the vast majority of people, it's a non-issue at typical use levels.

It's also worth keeping in mind that comedogenic and irritancy ratings are tested on individual ingredients, not finished formulas. The final product's formulation, concentration, and other ingredients all play a role in how something actually behaves on your skin.

Just so you know, the FDA ban on Red Dye No. 3 refers to CI 45430, not this ingredient. CI 45430 and CI 17200 are different chemical compounds with distinct safety and regulatory histories.

It's also worth noting that Red No. 3 (CI 45430) was already banned from cosmetics back in 1990, so the 2025 action just extended the ban to food and oral drugs. CI 17200 was never part of any of this.

Some people may experience allergies from this dye, especially asthmatics and those with an aspirin intolerance.