Mz skin Microtox Tightening Eye Serum

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.

Unlike most brighteners that target tyrosinase (the enzyme that synthesizes melanin), TXA works further upstream. It basically blocks your cells from receiving the signal to produce pigment.

This makes it one of the rare actives that works on three pathways at once:

This makes it effective for treating melasma, post-inflammatory hyperpigmentation (PIH), and sun-induced dark spots.

The most effective cosmetic concentration sits between 2-5% and going higher doesn't boost results.

Side effects are generally mild; occasional irritation, flaking, or dryness have been reported at the start of use. Overall, this ingredient is pretty well tolerated, even by sensitive skin types.

Another perk of this ingredient is that it does not cause photosensitivity, so it's safe to use in the AM and PM.

"Does it actually penetrate?" is the part that gets argued about online and the honest answer from research + clinical trials at this time is "yes, but not easily."

TXA is a small molecule that loves water and carries both a positive and negative charge at the same time. Skin's outer layer is oily so a water-loving molecule like this has a hard time getting through it. Liu et al. 2021 showed that it doesn't really stick around well in the deeper layer where pigment-making cells actually live.

A 2025 paper puts it simply: penetration is poor and it depends heavily on how the product is formulated (Winn et al., J Cosmet Dermatol).

But "poor" isn't "none" and the research is fairly clear that topical TXA does something. A 2026 review that pooled results from multiple studies found it helped with moderate melasma but it didn't outperform hydroquinone. Some individual studies at 3% and 5% went head to head with hydroquinone and help up well.

So the fair takeaway is that it works, it's just slower and fussier about formulation than other actives (how the serum is built matters a lot).

There's real evidence here and it's not just clinic marketing. Reviews of microneedling plus TXA report less pigmentation, less melanin, and less redness (Zhang et al., Chinese Journal of Plastic and Reconstructive Surgery, 2024).

The most useful study compared 42 patients getting microneedling plus TXA against microneedling on its own; the group that got the acid saw much bigger improvement. This suggests the acid is pulling its weight and the needling isn't doing all the work.

Just two things worth flagging here:

Oral TXA also works well for melasma and gets used in clinics. However, it is a systemic drug with clotting-related risks and needs a prescription. Injections into the skin have also been studied with good results.

Neither is something a cosmetic product can do, but they help explain why so much attention goes into getting the topical version right.

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.

They specifically help with reducing transepidermal water loss (TEWL) and supporting the skin's lipid matrix.

Studies show people deficient in essential fatty acids are prone to dermatitis and increased TEWL.

Besides fatty acids, it also contains tocopherols and phytosterols that provide antioxidant support.

Rapeseed oil is composed mostly of C16-18 fatty acids that the Malassezia species can metabolize, making it a potential trigger for fungal acne.

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.

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.

The reason this ingredient is so effective is because it forms a thin film on the skin that reduces transepidermal water loss (TEWL) while supplying linoleic acid to the stratum corneum to improve barrier strength.

The high linoleic acid content is particularly noteworthy for acne-prone skin.

Research suggests that acne-prone skin tends to be deficient in linoleic acid in sebum. Topical application may help replenish this to support a healthier follicular environment and less comedone-promoting sebum.

One randomized study found sunflower seed oil preserved skin barrier integrity in adult volunteers with and without atopic dermatitis (outperforming olive oil).

This ingredient is well-studied, gentle, and an effective emollient suitable for most skin types.

On fungal acne: This ingredient may not be Fungal acne (Malassezia folliculitis) safe. This is because it contains fatty acids with carbon chain lengths in the C11-C24 range.

Licorice Root also contains a flavonoid. Flavonoids are a natural substance from in plants. Flavonoids also have antioxidant properties.

Another component, glycyrrhizin, has been found to have anti-inflammatory and antimicrobial benefits. This may make licorice root extract effective at treating acne. However, more research is needed to support this.

Liquiritin is one of the flavone compounds found in licorice. It has been found to help lighten skin by preventing tyrosinase from reacting with tyrosine. When the two react, protein is converted to melanin. Melanin is the substance in your body that gives your features pigmentation.

This ingredient may not be fungal acne safe because research has shown that the Malassezia species can grow in the presence of fatty acid esters with chain lengths above C12 (and this one is C18).

While it does have a comedogenic rating of 4, the comedogenic rating scale was developed from rabbit ear models which has limited clinical relevance to human skin. Studies also show that comedogenic ingredients cannot predict how the overall formula will behave on human skin.

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%.

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.

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.

The marshmallow we eat today is based on an ancient Egyptian dessert made from this plant (Marshmallows do not contain this plant anymore).

Oryza Sativa Bran Extract contains numerous antioxidants such as ferulic acid. Antioxidants help fight free-radical molecules. Free-radical molecules are capable of damaging our cells and other genetic material.

These compounds protect your skin two ways:

1) They fight off free radicals, or the unstable molecules from things like sun and pollution that age and damage skin.
2) They help calm inflammation by switching off the chemical signals that tell skin to get red and irritated.

Lab studies also suggest that rosmarinic acid may help protect collagen and slow sugar-related damage to it.

The Cosmetic Ingredient Review has concluded rosemary-derived ingredients to be safe when formulated to be non-sensitizing.

Rosemary can occasionally cause allergic contact dermatitis (due to carnosol), so be sure to patch test if you have reactive or fragrance-sensitive skin.

An in-vivo study from the manufacturer found 95% of volunteers saw eye bag improvement by the end of the study.

Eye puffiness is caused by two major factors: fluid retention and fat.

Those with fluid retention may see improvement from using this ingredient. However, those with eye fat will need surgical intervention in order to get rid of puffiness.