Yves Rocher Balance Scalp Serum

The CIR Expert Panel has confirmed this ingredient to be nontoxic and clinical studies show no sensitization at cosmetic use concentrations.

True allergic reactions are quite rare: a 15-year retrospective study of 6,751 patients found only 0.31% had a positive reaction (and less than half were considered clinically relevant).

It seemed that when sensitization does occur, it's most commonly linked to topical medication (like corticosteroids) and not cosmetics. Allergic contact dermatitis also appears largely limited to individuals with underlying skin conditions.

Overall, propylene glycol is a well-studied ingredient that most people can tolerate without issue.

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.

This property also makes Pentylene Glycol a great texture enhancer. It can also help thicken or stabilize a product.

Pentylene Glycol also acts as a mild preservative and helps to keep a product microbe-free.

Some people may experience mild eye and skin irritation from Pentylene Glycol. We always recommend speaking with a professional about using this ingredient in your routine.

Pentylene Glycol has a low molecular weight and is part of the 1,2-glycol family.

You might have heard of "niacin flush", or the reddening of skin that causes itchiness. Niacinamide has not been found to cause this.

In very rare cases, some individuals may not be able to tolerate niacinamide at all or experience an allergic reaction to it.

If you are experiencing flaking, irritation, and dryness with this ingredient, be sure to double check all your products as this ingredient can be found in all categories of skincare.

When incorporating niacinamide into your routine, look out for concentration amounts. Typically, 5% niacinamide provides benefits such as fading dark spots. However, if you have sensitive skin, it is better to begin with a smaller concentration.

When you apply niacinamide to your skin, your body converts it into nicotinamide adenine dinucleotide (NAD). NAD is an essential coenzyme that is already found in your cells as "fuel" and powers countless biological processes.

In your skin, NAD helps repair cell damage, produce new healthy cells, support collagen production, strengthen the skin barrier, and fight environmental stressors (like UV and pollution).

Our natural NAD levels start to decline with age, leading to slower skin repair, visible aging, and a weaker skin barrier. By providing your skin niacinamide, you're recharging your skin's NAD levels. This leads to stronger, healthier, and younger looking skin.

Another name for vitamin B3 is nicotinamide. This vitamin is water-soluble and our bodies don't store it. We obtain Vitamin B3 from either food or skincare. Meat, fish, wheat, yeast, and leafy greens contain vitamin B3.

The type of niacinamide used in skincare is synthetically created.

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 has a low sensitization risk and testing shows it does not classify as a skin irritant or sensitizer.

FOS are usually produced from sugar beets and can also be found in foods like bananas, garlic, and onions.

Studies show inulin may help with controlling your skin's natural microbiota when applied topically.

The antioxidant potential of inulin varies depending on the source.

D-panthenol is also known as dexpanthenol. Most cosmetics use dexpanthenol or a mixture of D and L-panthenol.

Panthenol is famous due to its ability to go deeper into the skin's layers. Using this ingredient has numerous pros (and no cons):

Like hyaluronic acid, panthenol is a humectant. Humectants are able to bind and hold large amounts of water to keep skin hydrated.

This ingredient works well for wound healing. It works by increasing tissue in the wound and helps close open wounds.

Once oxidized, panthenol converts to pantothenic acid. Panthothenic acid is found in all living cells.

This ingredient is also referred to as pro-vitamin B5.

This palmitoleic content is also part of why macademia seed oil absorbs quickly and doesn't leave much of a greasy residue.

It also contains oleic acid, linoleic acid, and phytosterols that can help reduce redness.

In vitro research has shown the oil to have meaningful antioxidant activity, protect fats in the skin from oxidative damage, and slow down the enzyme that breaks down hyaluronic acid.

A 2024 clinical study found it effective at improving skin hydratino and reducing wrinkle appearance when formulated into nanoemulsions.

Because it carries oleic acid (C18) and palmitic acid (C16), this ingredient may not be fungal acne safe. This is because the Malassezia yeast metabolizes in the C11-24 chain length range.

You'll also see this ingredient listed as: Macadamia Ternifolia Seed Oil.

This is the same ingredient; M. ternifolia is an older INCI naming convention for the edible macadamia nut, while M. integrifolia is the species actually cultivated for oil production. Both names refer to the same oil.

This ingredient soothes skin inflammation by inhibiting inhibiting a part of the inflammation process.

Marigolds have been used in traditional medicine throughout Asia and Europe.

Folk medicine in European cultures used cornflowers to help treat eye inflammation.

Fun fact: Cornflowers were used to determine if love was returned. Young men would wear cornflowers and if the color faded quickly, it meant the love was not reciprocated.

Evidence for mint as a "treatment" ingredient is limited and depends heavily on the specific extract type and concentration.

In large percentages, peppermint extract may sensitize the skin.

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

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.

Lavender extract may have a scent. It contains linalool, a known allergen. However, lavender extract contains less linalool than lavender essential oil.

This ingredient improves spreadability and helps thicken a product.

According to manufacturers, it usually comes from vegetable-based saturated fatty acids. Common bases for this ingredient are coconut oil, palm kernel oil, or both.

Due to the melting point being close to skin temperature, it is usually used in lip products.

Triglycerides are a main component of fat in the human body.

Tocopheryl Acetate is commonly found in both skincare and dietary supplements.

Linalyl acetate is mildly toxic to humans and toxic to fish.

At higher doses or for those with sensitive skin, methol-type cooling can quickly turn into burning/irritation. It can also trigger irritant dermatitis or even allergic contact dermatitis. In a large patch-test dataset, peppermint oil had a low but positive rate for this.

In cosmetics, Cosmetic Safety Reviews (CIR) concludes that peppermint oil is safe to use when formulated to be non-sensitizing with some restrictions; for instance, pulegone, a naturally occurring component of peppermint oil, should not exceed 1%.

Since peppermint oil contains fragrance allergens such as limonene, linalool, and menthol, it can be sensitizing for those with rosacea, eczema, a broken skin barrier, or just sensitive skin in general.

In Japan, this ingredient is known as Hakka Yu.

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

Menthol also has antimicrobial properties.

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:

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.

Topically applied tocopherol has been shown to protect against UV damage by ramping up the skin's own natural defense enzymes.

It also acts as a skin conditioning agent; some studies show that regular topical use can improve the skin's water-binding capacity over 2-4 weeks.

This ingredient is especially loved for being a team player. When combined with Vitamin C, the photoprotective effect of both ingredients roughly doubles and the combo also helps reduce UV-induced DNA damage.

This ingredient has some brightening potential but it's more of a prevention ingredient than spot-fader. Cell studies show it can slow down melanin production but it's worth noting that it's not the most powerful brightener out there.

In formulations, it also serves as a stabilizer that helps protect other oxidation-prone ingredients from degrading.

Concentrations usually range from 0.1-1% in most leave-on products.

According to the EU, this ingredient is a known allergen and some people may develop skin sensitivity from repeated exposure.

Camphor also possesses antibacterial and antifungal properties.

One study found camphor to be a potential anti-wrinkle ingredient. This might be due to its ability to increase elastin and collagen production. Collagen and elastin are responsible for plump and youthful looking skin.

It is best to use cosmetics with a small amount of camphor under 11%. Using topical camphor may induce irritation and redness.

In the past, camphor was traditionally made by distilling the wood of the camphor tree.

Lab studies show carvone to have antioxidant and antimicrobial activity, but it is a recognized fragrance allergen. Carvone is a mild skin sensitizer while limonene is a well-known one.

In a 21-year retrospective from a Swedish patch test clinic, 3.5% of patients tested positive for sensitive towards carvone.

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.

Like all essential oils, this ingredient is a known sensitizer at higher concentrations. This is because this oil also contains known skin-irritating fragrances, limonene and camphor. Limonene and camphor are both known EU allergens.

While patchouli oil holds FDA GRAS ("generally recognized as safe") status, it is typically used at low levels and subject to usage guidelines.

Those with sensitive skin should patch test before using.

Besides cosmetics, eugenol is also added as a flavor in teas and cakes.

Geraniol can be found in many essential oils including Rose Oil and Citronella Oil. The scent of Geraniol is often described as "rose-like". Many foods also contain Geraniol for fruit flavoring.

Geraniol can irritate the skin when exposed to air. However, irritation depends on the ability of geraniol to penetrate into the skin. In general, geraniol is not able to penetrate skin easily.

Geraniol is colorless and has low water-solubility. However, it is soluble in common organic solvents.

Like citronellol, it is a natural insect repellent.

2,6-Octadien-1-ol, 3,7-dimethyl-, (2E)-