Inika Hyaluronic Hydration Complex

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.

Interestingly, the size of the molecule affects its behavior:

Some clinical evidence links low molecular weight versions to improved wrinkle depth, elasticity, anti-inflammatory effects, and barrier repair.

Many serums use a blend of both weights so you can get surface hydration plus longer-lasting and deeper effects.

You'll typically see concentrations between 0.1-2% for this ingredient.

Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.

The high vitamin C content of Kakadu plum also helps lighten skin. Vitamin C has been shown to block the process of skin darkening that leads to hyperpigmentation.

Kakadu plums have been used by indigenous cultures as medicine to help treat colds and as an antiseptic.

It's pretty compatible with most ingredients, but just sure to space out enzyme products with strong acids/retinoids to avoid over-doing it.

Maximum reported concentration is around 0.1% and most leave-on products use just 0.05%. If you see higher figures like 5-10%, this is usually the pre-diluted material from raw extract suppliers.

This ingredient has an assuring safety record and there's a lack of clinical case reports of dermatitis from using it.

The only caveat is allergy: patch test if you have a papaya or latex-fruit allergy.

Beyond exfoliation, this extract also contains natural sugars with humectant properties and some vitamin C.

Overall, this is a well-tolerated and low-risk ingredient unless you have a pineapple allergy.

It's often paired with Sodium Anisate as the two create a broad-spectrum preservative system that is popular in "natural" formulations.

This ingredient is water-soluble.

The CIR Expert Panel for Cosmetic Ingredient Safety has concluded this ingredient to be non-irritated and there are no restrictions for use in EU cosmetics. The FDA also allows this ingredient to be used as a food-grade flavoring agent.

The way it works is worth understanding; benzoic acid works when the formula is acidic. It is able to sneak into a microbe's cell and mess up how it functions to stop it from growing in an acidic product.

However, the acid switches to an inactive form and stops working if a product isn't acidic enough (above ~5 pH). This is why you'll often see it in low pH products or teamed up with other preservatives to cover the gap.

Safety wise, it's one of the better studied preservatives out there.

The Cosmetic Ingredient Review Expert Panel has concluded this ingredient to be safe for use in cosmetic formulations at concentrations up to 5%.

A large international review found this ingredient had no effects on the human body and had low irritation potential.

Just so you know, real world use is usually much lower than the 5% ceiling (usually 1% of less).

The EU caps it at 2.5% in rinse-off products, 1.7% in oral care, and 0.5% in leave-on products.

One thing worth mentioning (it's nothing to worry about): some people get a little stinging or flushing where they apply it. This isn't a true allergy; it's a temporary and harmless reaction. This is the same kind of mild tingle you might notice from sorbic acid.

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:

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.