Stila Cosmetics Stay All Day Dual-Ended Waterproof Liquid Eye Liner

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.

Oftentimes, Methylparaben is combined with other parabens to help increase the shelf life.

The safety of Methylparaben is currently being studied. While ongoing studies are looking into the safety of parabens, the results have been very mixed. Some studies have not found Methylparaben to be harmful.

Tromethamine helps balance the pH level of a product. Normal pH level of skin is slightly acidic (~4.75-5.5). The acidity of our skin is maintained by our glands and skin biome. Being slightly acidic allows our skin to create an "acid mantle". This acid mantle is a thin barrier that protects our skin from bacteria and contaminants.

Oral Tromethanmine is an anti-inflammatory drug but plays the role of masking, adding fragrance, and/or balancing pH in skincare.

1,3-Propanediol, 2-amino-2-(hydroxymethyl)-

You can usually find this ingredient in water-based products.

Parabens have come under controversy due to the claim they are hormone disruptors. Studies show conflicting results. We recommend speaking with a professional if you have any concerns.

Propylparaben is commonly found in food, medicine, and cosmetics.

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%.

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.

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.

Sodium benzoate works as a preservative by inhibiting the growth of bacteria inside of cells. It prevents the cell from fermenting a type of sugar using an enzyme called phosphofructokinase.

It is the salt of benzoic acid. Foods containing sodium benzoate include soda, salad dressings, condiments, fruit juices, wines, and snack foods.

Studies for using ascorbic acid and sodium benzoate in cosmetics are lacking, especially in skincare routines with multiple steps.

We always recommend speaking with a professional, such as a dermatologist, if you have any concerns.

In the US, this ingredient can only be used if it meets strict FDA specifications. Certain versions even require batch-by-batch certification after extensive safety evaluation.

In the European Union, this ingredient is permitted as a colorant and classified as a "nanomaterial" based on its particle size (meaning it requires deeper assessment).

The EU Scientific Committee on Consumer Safety (SCCS) has reviewed nano-sized carbon black specifically and concluded that it does not pose a risk to human health when used in cosmetic products applied to healthy, intact skin and formulated to avoid inhalation.

Studies support this regulatory stance. Laboratory studies on nano-carbon black show potential for cytotoxicity and inflammatory effects in immune cells; it is important to highlight these findings are based on in vitro (not done on a living organism) testing or inhalation scenarios rather than normal topical cosmetic use.

Occupational studies involving industrial workers exposed to airborne carbon black have not shown a clear link between cumulative exposure and cancer risk. These findings are not directly applicable to cosmetics; cosmetic formulations bind pigments within creams, gels, and liquids that are not inhaled.

Overall, evidence shows that this ingredient is safe under regulatory guidelines and purity standards, especially when formulated to avoid airborne exposure.

Even with regulatory approval and a long history of use, some consumers might prefer to avoid ingredients that are petroleum-derived or that fall under the “nanomaterial” category.

Choosing whether to use CI 77266 isn’t necessarily about safety alone; it can also be about personal philosophy, comfort level with synthetic versus natural ingredients, and how much weight you place on ongoing research and regulatory oversight.

Makeup is highly individual, and personal preference plays an important role in deciding what feels right for you.

A 2021 paper looked at skincare formulations containing iron oxides and found that they reduced transmission of blue light when measured optically. In simple terms, the pigment particles helped block or scatter part of the visible light spectrum in lab testing and the authors suggest this could translate into better protection against blue-light-related skin effects.

There is also clinical and experimental research showing that tinted products containing iron oxides can reduce visible light-induced pigmentation:

Please note, whether a product reduces visible or blue light depends on things like:

In the EU's CosIng database, iron oxides are only listed as a colorant. CosIng groups ingredients by their main cosmetic role, such as colorant, preservative, or UV filter.

Though studies say iron oxides can "attenuate blue light", they're describing an optical property and not an officially recognized cosmetic function.

So CosIng isn’t contradicting the research. It’s just classifying iron oxides by what they officially are: pigments that add color.

In the EU, both of these colors must be labeled as 'CI 77510'.

This property also makes Pentylene Glycol a great texture enhancer. It can also help thicken or stabilize a product.

Pentylene Glycol also acts as a mild preservative and helps to keep a product microbe-free.

Some people may experience mild eye and skin irritation from Pentylene Glycol. We always recommend speaking with a professional about using this ingredient in your routine.

Pentylene Glycol has a low molecular weight and is part of the 1,2-glycol family.

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

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