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Concentration use usually lands somewhere between 0.1-3% for face products.

Allergies to this ingredient are uncommon and most reported cases from from medication creams rather than cosmetics.

This ingredient does have a comedogenic rating of 2, 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.

The Malassezia yeast feeds on fatty alcohols with a chain length above 12 carbons, and this ingredient is a C14 primary fatty alcohol. This ingredient may not be fungal acne safe.

If it does somehow make it onto your skin, it is chemically inert and does not penetrate or get absorbed into skin. Safety assessments note that adverse skin reactions to this ingredient are uncommon.

It is volatile, meaning it only remains on skin for less than 10 seconds before evaporating. It doesn't really linger long enough on skin to act as a skincare ingredient in any meaningful way.

Hairspray concentrations are between 6-17%.

The CIR Expert Panel concluded it to be safe as a cosmetic ingredient under present concentration and usage.

This ingredient is considered gentle and non-comedogenic. However, it may still be irritating for some.

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.

A 2012 assessment found this ingredient is used in leave-on products at up to 21%, which is at the very high end for the category; most cosmetic use is far lower and typically in the single digits.

A true allergy to Laureth-4 is rare; similar alcohol ethoxylates tested negative for skin sensitization in undiluted guinea pig studies, and related compounds were non-sensitizing in Magnusson-Kligman maximization tests.

There is one caveat for this whole ingredient family: ethoxylated surfactants slowly oxidize when exposed to air, and it's the oxidation products, not the fresh material, that act as sensitizers. This is mostly a formulation and shelf life issue.

Dr. James Fulton's rabbit ear test from the 1980's scored this ingredient as a 5 on the comedogenic scale. Fulton himself described the rabbit ear as not an ideal model and the tests used undiluted ingredients on rabbit ears, which are more reactive than human facial skin.

Dr. Draelos later used a human assay on finished cosmetic products and found that products built with so-called comedogenic ingredients are not necessarily comedogenic themselves.

This ingredient can be potentially pore clogging if it appears high in the ingredient list of a leave-on product.

The fungal acne picture is actually reassuring: Malassezia uses fatty acids from its surroundings (C11-24). This ingredient has nothing for the Malassezia yeast to use since it is an alcohol and not an acid.

Supporting this, closely related ethoxylated alcohol detergents like Ceteth-20 get used in Malassezia lab work as neutral carriers to disperse a separately added fatty acid (not as the food source itself).

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.

For instance, Habanolide is a proprietary trade name for a specific aroma chemical. When used as a fragrance ingredient in cosmetics, most aroma chemicals fall under the broad labeling category of “FRAGRANCE” or “PARFUM” according to EU and US regulations.

The term 'parfum' or 'fragrance' is not regulated in many countries. In many cases, it is up to the brand to define this term.

For instance, many brands choose to label themselves as "fragrance-free" because they are not using synthetic fragrances. However, their products may still contain ingredients such as essential oils that are considered a fragrance by INCI standards.

One example is Calendula flower extract. Calendula is an essential oil that still imparts a scent or 'fragrance'.

Depending on the blend, the ingredients in the mixture can cause allergies and sensitivities on the skin. Some ingredients that are known EU allergens include linalool and citronellol.

Parfum can also be used to mask or cover an unpleasant scent.

The bottom line is: not all fragrances/parfum/ingredients are created equally. If you are worried about fragrances, we recommend taking a closer look at an ingredient. And of course, we always recommend speaking with a professional.

Due to the large molecule size, this ingredient is unlikely to penetrate skin.

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

Two clinical studies in postmenopausal women found that applying argan oil for 60 days significantly improved skin elasticity and moisturization (reduced transepidermal water loss and increased epidermal water content).

Since it is high in oleic and linoleic acid, this ingredient may not be fungal acne safe. Both of these fall in the C11-C24 range that Malassezia yeast can metabolize.

Rice extract has many skin benefits. Read more about rice extract here.

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.

Rosacea skin has a lower threshold for acids generally, with 62.5% of rosacea subjects in one study reacting to lactic acid in a sting test. This is why we mark citric acid as a potential rosacea trigger.

However, this ingredient shows up as a pH adjuster or chelator at roughly 0.1-1% in many products. These low levels are unlikely to be an issue for rosacea skin and becomes a potential trigger at exfoliating concentrations (20%). Because everybody's skin is unique, we recommend a patch test if you are unsure.