Almay Liquid Eyeliner

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.

Its job in a formula is boring, but useful:

Typical concentrations range from 0.1-50% and it's usually low single digits in leave-on skincare.

One thing that sets it apart from other fatty alcohols is that it's used deliberately as a penetration enhancer in topical drug delivery. This is because it "loosens" the packing of your skin's surface lipids a bit so other ingredients can get through more easily.

A study on human skin found both Oleic Acid and Oleyl Alcohol at 0.75% increased how much topical anti-inflammatory drug got through with the effect leveling off after about 12 hours.

Allergic reactions are uncommon but documented; there's a published case of a patient with atopic dermatitis who developed severe allergic contact dermatitis from a prescription cream. A patch testing traced it specifically to the Oleyl Alcohol in the formula rather than the active drug.

The Cosmetic Ingredient Review Expert Panel concluded Oleyl Alcohol is safe as used in cosmetics. Acute toxicity testing showed very low toxicity, animal tests showed minimal to mild skin irritation, human patch testing found low irritation and sensitization potential, and no phototoxicity or photosensitization has been reported.

It's reasonable to patch test if you have eczema, a known fatty alcohol allergy, or you've reacted to Stearyl or Cetyl Alcohol before.

Oleyl Alcohol scored a 4 out of 5 for comedogenicity in the 1989 rabbit ear study. Just know the rabbit ear test has real limits:

It's worth watching if you're acne-prone and how you will react to it really comes down to concentration, formula, and your skin.

The culprit behind fungal acne, the Malassezia yeast, feeds on fatty acids with carbon chain lengths between C11-C24. Oleic Acid, at C18, falls right into that sweet spot.

In vitro studies have shown that Oleic Acid is one of the fatty acids that induce rapid Malassezia growth in lab settings. Since this ingredient is created from Oleic Acid, it may not be fungal acne safe.

Like other types of silica, this ingredient can be used to thicken a product. As an absorbent, it may be used to absorb extra water or help prevent clumping.

Although “aluminum” in an ingredient name can raise red flags for some consumers, the form and usage context matter significantly. For typical topical applications, there is no substantial evidence of health risks - such as cancer, neurotoxicity, or systemic “aluminum overload.”

Safety-wise, the CIR Expert Panel has concluded it to be safe in cosmetics when formulated to be non-irritating and non-sensitizing.

Free stearic acid is a C18 fatty acid that the Malassezia yeast can substrate, so this ingredient may not be fungal acne safe.

This ingredient does have a comedogenic rating of 2-3, but this doesn't mean a formula with this ingredient will clog pores.

Human testing has proved that any finished product with this ingredient won't automatically make you break out; it really comes down to concentration, formula, and your skin.

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.

This ingredient is typically used in concentrations between 1-10%. Studies have found it to be non-sensitizing, non-phototoxic, and non-photoallergenic.

A close cousin of this ingredient is Glyceryl Stearate SE ("self-emulsifying"). This just has a small amount of sodium or potassium stearate added so it can emulsify without a co-emulsifier.

Since this ingredient is an ester of a C18 fatty acid, it may not be fungal acne safe. The Malassezia yeast can potentially metabolize within the C11-C24 range.

Fun fact: The human body also creates Glyceryl Stearate naturally.

Fun fact: Cellulose is the most abundant form of organic polymer on Earth.

It can also form a thin protective film on skin. One study found that a formula using this polymer helped slow down how quickly other ingredients (like DEET) were absorbed through skin.

A 2024 study of over 1,300 patients confirmed that sensitization to this ingredient is rare. It is also non-mutagenic and has a clean track record.