Thalgo La Beauté Marine Spiruline Boost Energising Detoxifying Serum

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.

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.

This ingredient gets a bad rep because it is irritating and drying due to its astringent property. Astringents draw out natural oils in tissue to constrict pores and dry out your skin.

However, alcohol denat. is not all that bad.

Due to its low molecular weight, alcohol denat. tends to evaporate quickly. One study on pig skin found half of applied alcohol evaporated in 10 seconds and less than 3% stayed on skin.

This also helps other ingredients become better absorbed upon application.

Studies are conflicted about whether this ingredient causes skin dehydration. One study from 2005 found adding emollients to propanol-based sanitizer decreased skin dryness and irritation. Another study found irritation only occurs if your skin is already damaged.

Small amounts of alcohol are generally tolerated by oily skin or people who live in humid environments.

The rule of thumb is this ingredient will probably not affect your skin much if it is near the end of an ingredients list.

One thing to note:
People with ALDH2 (aldehyde dehydrogenase 2) deficiency may experience skin irritation from continued alcohol use. About 8% of the world's population have this deficiency.

The Cosmetic Ingredient Review Expert Panel has determined denatured alcohols to be safe for use in concentrations between 0.05% and 12% (depending on which denaturant is used).

Also...

This ingredient has antimicrobial and solvent properties.

The antimicrobial property helps preserve products and increase their shelf life. As a solvent, it helps dissolve other ingredients.

Look for formulas that contain glycerin, hyaluronic acid, or panthenol if you want to offset any drying effect.

This ingredient will trip away your skin's natural oils/lipids that help it lock in moisture. This can worsen dryness, trigger eczema flare-ups, and aggravate rosacea.

Be sure to patch test any product with this ingredient if you have dry or sensitive skin, eczema, or rosacea.

Either way, you're getting water + a cocktail of minerals and trace elements (like magnesium, calcium, potassium sodium, etc).

Officially, COSIng recognizes this ingredient as a humectant that holds and retains moisture, and solvent that helps dissolve other ingredients.

The claims about this ingredient come from its minerals. A 2025 systematic review found that seawater-based therapy showed moderate effectiveness at reducing atopic dermatitis severity and improving skin barrier function.

It also showed favorable safety profile and very minimal adverse effects.

The underlying studies pointed to improvements in stratum corneum hydration, lower transepidermal water loss (TEWL), and a healthier microbial balance.

Much of this benefit is actually attributed to magnesium: a 2005 study found that bathing in a magnesium-rich Dead sea salt solution improved skin barrier function, boosted hydration, and reduced inflammation in atopic dry skin.

It's worth nothing most of this evidence comes from bathing/soaking protocols and mineral-rich waters like the Dead Sea (not necessarily a few drops on an ingredient list).

Overall, this is a gentle, well-tolerated, water-phase ingredient that can offer light hydration and a little mineral boost.

The only caveat is that very high salt concentrations can be drying for already-dry skin.

The polysaccharides do most of the work: they bind water at the skin surface for a light, non-greasy hydration boost. And one of the polysaccharides, glycomannan, is linked to fibroblast stimulation + collagen synthesis. This is also why aloe has such a long track record in wound and burn healing.

This ingredient is also calming with anti-inflammatory and mild antimicrobial activity, making it a great pick for sensitive, irritated, or post-sun skin.

Realistic expectations matter though; the solid evidence is mostly limited to hydration, soothing, and wound support. Deeper claims about anti-aging or sun protection are not well backed, and science reviews note it does not prevent radiation-induced skin injury.

Because it plays well with almost everything, it's commonly used as a base alongside other actives like niacinamide or vitamin C.

Typical usage concentrations range from 0.5% (where hydration benefits already show up) all the way to 90%+ (where it replaces water as the main base).

The safety for this ingredient is well-establish as well. Overall, this is a great supporting ingredient for those who want a boost in hydration.

Spirulina Platensis also contains Vitamin A, Vitamin E, and proteins.

Due to its large molecule size, it doesn't penetrate beyond the skin's surface.

This ingredient has a solid regulatory track record; the CIR Expert Panel first concluded it was safe for use in cosmetics at concentrations up to 100% in 1997. A 2012 reassessment reaffirmed that finding. Safety studies have also found no irritation or evidence of toxicity.

A 2019 study did find this ingredient to grow Malassezia, so this ingredient may not be fungal acne safe.

Though it can't kill microbes on its own, it works as a good supporting agent when combined with other preservatives like Phenoxyethanol or 1,2-Hexanediol.

This ingredient naturally occurs as piceol in Norwegian spruce needles (~0.4-1.1% dry weight and in cloudberries). Though the cosmetic-grade material is synthesized for purity and consistency.

You'll usually see it used at low levels and suppliers recommend up to 1% added to a water phase.

Safety testing was done at concentrations like 0.05% in SPF products and 0.5% in a Human Repeated Insult Patch Test. The safety evidence is assuring; this ingredient is safe for cosmetics in current use and also holds safety status as a food flavoring as well.

An honest caveat: the "soothing" and "anti-inflammatory" claims come mostly from supplier marketing rather than published clinical trials. The Cosmetic Ingredient Review's own literature search found no useful efficacy studies on this ingredient.

So the antioxidant and preservative-boosting roles are the well supported ones while the calming benefit is plausible but thinly evidenced.

Overall, this is a well-tolerated, low-irritation multitasker that quietly helps a formula stay fresh and stable.

On the safety side, the Cosmetic Ingredient Review Expert Panel has concluded this ingredient to be safe as used in current cosmetic practices + concentrations.

Typical use levels in a formula run about 1-5%.

In cosmetics, HJE works mainly to soften skin, reinforce the barrier, and lock in moisture by reducing water loss. This ingredient also holds onto the skin even after rinsing which is why you'll see it in cleansers or wipes.

There's a decent clinical backing for the moisturizing claims: a small controlled study found that pairing HJE with glycerin lowered transepidermal water loss significantly than glycerin alone (and this effect lasted up to 24 hours).

Follow-up work showed HJE appear to "trap" glycerin in the film they form on skin to boost its hydrating power.

Typical use levels are low: the glycering-synergy research used around 1.25% (a common pairing is roughly 1.25% HJE and 3.75% glycerin).

This ingredient has been found safe as used in cosmetics with low irritation risk.

As for fungal acne, the fatty acids and alcohols in jojoba fall in roughly the C18-24 range. This overlaps the C11-24 window that Malassezia yeast can feed on in lab studies, so this ingredient may not be fungal acne safe.

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.

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

Because hydrolyzed hyaluronic acid is smaller in size, it can slip past your outermost layer of skin more easily than full-sized HA.

Most formulations will combine all sizes to get the best of both worlds.

Typical usage levels range from 0.01-1%. Any percentage higher than 2% might become goopy and tacky.

It also needs to be neutralized to actually thicken, and because it is a large molecule, it doesn't really penetrate the skin barrier.

Allergy-wise, the risk is very low. Clinical studies show carbomers have low potential for skin irritation/sensitization even at concentrations up to 100%.

A 2024 UK study patch-tested 1,302 patients and found true allergy to the parent group of carbomer to be rare with no confirmed relevant reactions.

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.

Both potassium sorbate and sorbic acid can be found in baked goods, cheeses, dried meats, dried fruit, ice cream, pickles, wine, yogurt, and more.

You'll often find this ingredient used with other preservatives.

The unique structure of silica enhances the spreadability and adds smoothness, making it a great texture enhancer.

It is also used as an active carrier, emulsifier, and mattifier due to its ability to absorb excess oil.

In some products, tiny microneedles called spicules are made from silica or hydrolyzed sponge. When you rub them in, they lightly polish away dead skin layers and enhance the penetration of active ingredients.

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.

Hexyl Cinnamal is not water soluble but is soluble in oils.

Limonene acts as an antioxidant, meaning it helps neutralize free radicals.

When exposed to air, oxidized limonene may sensitize the skin. Because of this, limonene is often avoided by people with sensitive skin.

The term '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.

This ingredient has a scent that is floral, spicy tropical, and citrus-like.

While Benzyl Salicylate has been associated with contact dermatitis and allergies, emerging studies show it may not be caused by this ingredient alone.

However, this ingredient is often used with fragrances and other components that may cause allergies. It is still listed as a known allergen in the EU. We recommend speaking with a professional if you have concerns.

Another study from 2021 shows Benzyl Salicylate may have anti-inflammatory properties.

You should know this ingredient is a known EU fragrance allergen.

Animal studies classifies this ingredient as a weak-to-moderate skin sensitizer and clinical patch testing on eczema patients confirmed it to be both a contact allergen and irritant.

The term 'citral' is a collective term for two geometric isomers: geranial/Citral A and neral/Citral B.

The term '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.