Follow us on our new Insta page »
Rationale #5 The Milk Concentrate

#5 The Milk Concentrate

Clarifies and hydrates
Uploaded by: mon on

Ingredients overview

Water/​Aqua, Propanediol, Methylpropanediol, Caprylyl Glycol, Phenylpropanol, Octyldodecanol, Polyglyceryl-6 Distearate, Jojoba Esters, Polyglyceryl-3 Beeswax, Cetyl Alcohol, C10-18 Triglycerides, Piroctone Olamine, Sodium Stearoyl Glutamate, Xanthan Gum, Zinc Pca, Yeast Extract, Soy Amino Acids, Calcium Gluconate, Hibiscus Sabdariffa, Rose Flower Extract, Citrus Aurantium Bergamia (Bergamot) Fruit Oil, Tasmannia Lanceolata (Mountain Pepper Berry) Fruit Extract, PEG-40 Hydrogenated Castor Oil, Trideceth-9, Ceramide EOS, Barklya Syringifolia (Crown Of Gold) Flower Extract, Ceramide NS, Eugenia Caryophyllus (Clove) Leaf Oil, Brachychiton Acerifolius (Flame Tree) Flower Extract, Telopea Speciosissima (Waratah) Flower Extract, Citrus Aurantium Amara (Neroli) Oil, Banksia Serrata (Banksia) Flower Extract, Glutamic Acid, Citrus Aurantium Bergamia (Bergamot) Leaf Oil, Davidsonia Pruriens (Davidson Plum) Fruit Extract, Terminalia Ferdinandiana (Kakadu Plum) Fruit Extract, Zinc Gluconate, Citrus Aurantium Dulcis (Orange) Oil, Citrus Australasica (Finger Lime Caviar) Fruit Extract, Melaleuca Alternifolia (Snowflower) Leaf Extract, Santalum Acuminatum (Quandong) Fruit Extract, Lysine, Cholesterol, Ceramide EOP, Histidine, Arginine, Ceramide AP, Caprooyl Phytosphingosine, Aspartic Acid, Threonine, Serine, Proline, Glycine, Alanine, Valine, Methionine, Propylene Glycol, Citrus Aurantium Dulcis (Orange) Flower Water, Isoleucine, Pelargonium Graveolens (Geranium) Oil, Leucine, Citrus Medica Limonum (Lemon) Peel Oil, Tyrosine, Cysteine, Magnesium Aspartate, Copper Gluconate, Ceteareth-25, Glycerin, Behenic Acid, Ceramide NP, Caprooyl Sphingosine, Litsea Cubeba (May Chang) Fruit Oil, Citrus Grandis (Grapefruit) Peel Oil, Juniperus Mexicana (Juniper) Extract, Phenylalanine, Lavandula Hybrida (Lavandin) Oil, Citrus Aurantium Dulcis (Orange) Peel Extract, Citral, Limonene, Linalool, Geraniol, Citronellol, Eugenol

Highlights

#alcohol-free
Alcohol Free

Skim through

Ingredient name what-it-does irr., com. ID-Rating
Water/Aqua solvent
Propanediol solvent, moisturizer/​humectant
Methylpropanediol solvent
Caprylyl Glycol moisturizer/​humectant, emollient
Phenylpropanol perfuming, solvent
Octyldodecanol emollient, perfuming
Polyglyceryl-6 Distearate emulsifying
Jojoba Esters soothing, emollient, moisturizer/​humectant
Polyglyceryl-3 Beeswax emulsifying
Cetyl Alcohol emollient, viscosity controlling 2, 2
C10-18 Triglycerides emollient, solvent
Piroctone Olamine preservative
Sodium Stearoyl Glutamate emulsifying, surfactant/​cleansing
Xanthan Gum viscosity controlling
Zinc Pca anti-acne, moisturizer/​humectant goodie
Yeast Extract moisturizer/​humectant goodie
Soy Amino Acids moisturizer/​humectant goodie
Calcium Gluconate moisturizer/​humectant
Hibiscus Sabdariffa
Rose Flower Extract
Citrus Aurantium Bergamia (Bergamot) Fruit Oil perfuming icky
Tasmannia Lanceolata (Mountain Pepper Berry) Fruit Extract
PEG-40 Hydrogenated Castor Oil emulsifying, surfactant/​cleansing
Trideceth-9 emulsifying, surfactant/​cleansing
Ceramide EOS
Barklya Syringifolia (Crown Of Gold) Flower Extract antioxidant, moisturizer/​humectant
Ceramide NS
Eugenia Caryophyllus (Clove) Leaf Oil perfuming
Brachychiton Acerifolius (Flame Tree) Flower Extract antioxidant
Telopea Speciosissima (Waratah) Flower Extract antioxidant, skin brightening, moisturizer/​humectant
Citrus Aurantium Amara (Neroli) Oil icky
Banksia Serrata (Banksia) Flower Extract
Glutamic Acid moisturizer/​humectant
Citrus Aurantium Bergamia (Bergamot) Leaf Oil
Davidsonia Pruriens (Davidson Plum) Fruit Extract antioxidant, moisturizer/​humectant
Terminalia Ferdinandiana (Kakadu Plum) Fruit Extract antioxidant, skin brightening
Zinc Gluconate anti-acne, soothing goodie
Citrus Aurantium Dulcis (Orange) Oil perfuming icky
Citrus Australasica (Finger Lime Caviar) Fruit Extract antioxidant, moisturizer/​humectant
Melaleuca Alternifolia (Snowflower) Leaf Extract antimicrobial/​antibacterial, perfuming
Santalum Acuminatum (Quandong) Fruit Extract antioxidant, moisturizer/​humectant
Lysine
Cholesterol skin-identical ingredient, emollient 0, 0 goodie
Ceramide EOP skin-identical ingredient goodie
Histidine skin-identical ingredient, moisturizer/​humectant goodie
Arginine skin-identical ingredient goodie
Ceramide AP skin-identical ingredient goodie
Caprooyl Phytosphingosine
Aspartic Acid skin-identical ingredient goodie
Threonine skin-identical ingredient goodie
Serine skin-identical ingredient goodie
Proline skin-identical ingredient goodie
Glycine skin-identical ingredient goodie
Alanine skin-identical ingredient goodie
Valine skin-identical ingredient goodie
Methionine
Propylene Glycol moisturizer/​humectant, solvent 0, 0
Citrus Aurantium Dulcis (Orange) Flower Water
Isoleucine skin-identical ingredient goodie
Pelargonium Graveolens (Geranium) Oil perfuming icky
Leucine
Citrus Medica Limonum (Lemon) Peel Oil
Tyrosine
Cysteine antioxidant
Magnesium Aspartate
Copper Gluconate soothing goodie
Ceteareth-25 surfactant/​cleansing, emulsifying
Glycerin skin-identical ingredient, moisturizer/​humectant 0, 0 superstar
Behenic Acid surfactant/​cleansing, emulsifying 0, 0
Ceramide NP skin-identical ingredient goodie
Caprooyl Sphingosine
Litsea Cubeba (May Chang) Fruit Oil perfuming
Citrus Grandis (Grapefruit) Peel Oil perfuming icky
Juniperus Mexicana (Juniper) Extract
Phenylalanine skin-identical ingredient goodie
Lavandula Hybrida (Lavandin) Oil emollient
Citrus Aurantium Dulcis (Orange) Peel Extract perfuming, viscosity controlling
Citral perfuming icky
Limonene perfuming, solvent icky
Linalool perfuming icky
Geraniol perfuming icky
Citronellol perfuming icky
Eugenol perfuming icky

Rationale #5 The Milk Concentrate
Ingredients explained

Also-called: Aqua;Water | What-it-does: solvent

Good old water, aka H2O. The most common skincare ingredient of all. You can usually find it right in the very first spot of the ingredient list, meaning it’s the biggest thing out of all the stuff that makes up the product. 

It’s mainly a solvent for ingredients that do not like to dissolve in oils but rather in water. 

Also-called: Zemea | What-it-does: solvent, moisturizer/humectant

Propanediol is a natural alternative for the often used and often bad-mouthed propylene glycol. It's produced sustainably from corn sugar and it's Ecocert approved. 

It's quite a multi-tasker: can be used to improve skin moisturization, as a solvent, to boost preservative efficacy or to influence the sensory properties of the end formula. 

What-it-does: solvent

It's a type of glycol that - according to the manufacturer - is an extremely good replacement for other glycols like propylene or butylene glycol. Its main job is to be a solvent, but it has also very good antimicrobial properties and acts as a true preservative booster. Also helps with skin hydration without stickiness or tacky feel.

It’s a handy multi-tasking ingredient that gives the skin a nice, soft feel. At the same time, it also boosts the effectiveness of other preservatives, such as the nowadays super commonly used phenoxyethanol

The blend of these two (caprylyl glycol + phenoxyethanol) is called Optiphen, which not only helps to keep your cosmetics free from nasty things for a long time but also gives a good feel to the finished product. It's a popular duo.

What-it-does: perfuming, solvent

A naturally occurring floral component with a delicate scent that can mask the odor of other raw materials but is not noticeable in the final product. It also has remarkable antimicrobial and preservative boosting abilities and can help to create "preservative-free" formulas.

What-it-does: emollient, perfuming

A clear, slightly yellow, odorless oil  that's a very common, medium-spreading emollient. It makes the skin feel nice and smooth and works in a wide range of formulas.

What-it-does: emulsifying

We don't have description for this ingredient yet.

Jojoba-derived emollient wax esters (fatty acid + fatty alcohol) that make your skin feel nice and smooth. Chemically speaking, pure jojoba oil is also a wax ester (read our shiny explanation here), however, the ingredients called jojoba esters on the ingredient lists are made from jojoba oil and/or hydrogenated jojoba oil via interesterification. 

They have multiple versions with variable fatty acid chain length and the ingredient can have a liquid, a creamy, a soft or firm paste, or even a hard wax consistency. The common thing between all versions is, that unlike most normal triglyceride oils, jojoba esters have superior stability, provide non-greasy emolliency and are readily absorbed into the skin

What-it-does: emulsifying

We don't have description for this ingredient yet.

What-it-does: emollient, viscosity controlling, emulsion stabilising | Irritancy: 2 | Comedogenicity: 2

A so-called fatty (the good, non-drying kind of) alcohol that does all kinds of things in a skincare product: it makes your skin feel smooth and nice (emollient), helps to thicken up products and also helps water and oil to blend (emulsifier). Can be derived from coconut or palm kernel oil.

What-it-does: emollient, solvent

We don't have description for this ingredient yet.

What-it-does: preservative

We don't have description for this ingredient yet.

An amino acid-based emulsifier that helps water and oil to mix and stay that way. It is considered as natural, environmentally friendly, and hypoallergenic. 

It's one of the most commonly used thickeners and emulsion stabilizers. If the product is too runny, a little xanthan gum will make it more gel-like. Used alone, it can make the formula sticky and it is a good team player so it is usually combined with other thickeners and so-called rheology modifiers (helper ingredients that adjust the flow and thus the feel of the formula). The typical use level of Xantha Gum is below 1%, it is usually in the 0.1-0.5% range. 

Btw, Xanthan gum is all natural, a chain of sugar molecules (polysaccharide) produced from individual sugar molecules (glucose and sucrose) via fermentation. It’s approved by Ecocert and also used in the food industry (E415). 

Zinc Pca - goodie

If you have oily, acne-prone skin, Zinc PCA is one of the actives to put on your "TO TRY" list.

It's a synergistic association of two great things: Zinc and L-PCA. The Zinc part is there to help normalize sebum production and limit the proliferation of evil acne-causing bacteria. L-PCA stands for pyrrolidone carboxylic acid and it's a key molecule in the skin that helps with processes of hydration and energy (it's actually an NMF, a natural moisturizing factor).

Yeast Extract - goodie
What-it-does: moisturizer/humectant

You probably know yeast from the kitchen where you put it into milk with a little sugar and then after a couple of minutes brownish bubbles form. That is the fungi fermenting the sugar

As for skin care, yeast contains beta-glucan that is a great soothing ingredient and also a mild antioxidant.  The yeast extract itself is a silky clear liquid that has some great moisturizing, skin protecting and film-forming properties on the skin. 

What-it-does: moisturizer/humectant

Soy Amino Acids are the little components that come from totally chopping up a soy protein. It is a low-molecular-weight water-binding ingredient, that can help to moisturize deeper layers of skin or hair. 

What-it-does: moisturizer/humectant

We don't have description for this ingredient yet.

Also-called: Hibiscus Extract;Hibiscus Sabdariffa Flower Extract

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

Also-called: Bergamot Fruit Oil | What-it-does: perfuming

The essential oil coming from the fruit (probably the rind) of the bergamot orange.  It's a common top note in perfumes and contains (among others) fragrant compounds limonene (37%), linalyl acetate (30%) and linalool (8.8%). 

A well-known issue with bergamot oil (apart from the fragrance allergens) is that it contains phototoxic compounds called furanocoumarins, but more and more commonly furanocoumarin-free versions are used in cosmetic products. Still, if you have sensitive skin and prefer fragrance-free products, bergamot oil is not for you.

We don't have description for this ingredient yet.

A mildly viscous, amber-colored liquid with fatty odor, made from Castor Oil and polyethylene glycol (PEG).

If it were a person, we’d say, it’s agile, diligent & multifunctional. It’s mostly used as an emulsifier and surfactant but most often it is used to solubilize fragrances into water-based formulas.

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

What-it-does: perfuming

We don't have description for this ingredient yet.

What-it-does: antioxidant

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

Also-called: Bitter Orange Flower Oil, Neroli Oil;Citrus Aurantium Amara Flower Oil

The essential oil coming from the flowers of bitter orange (which is the sister of the sweet orange we all know and eat). It contains several fragrance components including linalool (around 30%) and limonene (around 10%) and has a lovely sweet smell

As it's an essential oil with lots of fragrant components, be careful with it if your skin is sensitive.  

We don't have description for this ingredient yet.

What-it-does: moisturizer/humectant

Glutamic acid is a little molecule and non-essential (our body can synthesize it) amino acid with the important job of being a neurotransmitter in the human body meaning that it helps your nervous system work correctly. 

As for what it's doing in cosmetics, Glutamic acids' main thing (similar to other amino acids) is being a humectant moisturizer and skin-conditioning agent (sidenote: if you attach lots of glutamic acid molecules, you get polyglutamic acid that is claimed to be a better than hyaluronic acid humectant). It also seems to affect skin barrier repair, however, it is not clear-cut in which direction.

What-it-does: astringent

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

What-it-does: antioxidant, skin brightening

We don't have description for this ingredient yet.

What-it-does: anti-acne, soothing, deodorant

If you are fighting acne and have looked into oral supplements, chances are that zinc gluconate sounds familiar to you. It is a zinc salt that has research proving it to be effective against inflammatory acne, though not quite as effective as the antibiotic minocycline (31.2% vs. 63.4% success rate). However, zinc supplements are easily available, have little-to-no side effects, so supplementing them with a 30mg per day dose can still be a good idea.

As for smearing zinc gluconate all over your face, it is also not a bad idea. Zinc has multiple magic abilities: it is antibacterial (including evil, acne-causing P. acnes) and sebum-regulating (5α-reductase inhibitor), great for acne-prone skin types. It also stimulates antioxidant enzyme systems (mainly superoxide dismutase) and has nice wound healing abilities acting mainly in the first, proliferation phase. So great for skin types in need of healing and soothing.

Also-called: Orange Oil | What-it-does: perfuming

The essential oil coming from the sweet orange. In the case of orange (and citruses in general), the essential oil is mainly in the peel of the fruit, so it's pretty much the same as the orange peel oil (also has the same CAS number - a unique ID assigned to chemicals).

Its main component is limonene (up to 97%), a super common fragrant ingredient that makes everything smell nice (but counts as a frequent skin sensitizer). 

We don't have description for this ingredient yet.

Also-called: Tea Tree Leaf Extract | What-it-does: antimicrobial/antibacterial, perfuming

When it comes to Tea Tree, the essential oil is the one that steals the show with its well-documented antimicrobial and anti-acne effects. The extract is not very well defined, and it probably contains the active components of the oil in much-reduced concentrations. Manufacturers still mention soothing, antimicrobial, purifying and antiseptic properties for the tea tree extract. 

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

Cholesterol - goodie
What-it-does: skin-identical ingredient, emollient | Irritancy: 0 | Comedogenicity: 0

It's one of the important lipids that can be found naturally in the outer layer of the skin. About 25% of the goopy stuff between our skin cells consists of cholesterol. Together with ceramides and fatty acids, they play a vital role in having a healthy skin barrier and keeping the skin hydrated. 

Apart from being an important skin-identical ingredient, it's also an emollient and stabilizer

Ceramide EOP - goodie
Also-called: Ceramide 1 | What-it-does: skin-identical ingredient

Ceramides get quite a lot of hype recently and good news: there is a reason for that. But before we go into the details, let's just quickly define what the heck ceramides are:

They are waxy lipids that can be found naturally in the outer layer of the skin (called stratum corneum - SC). And they are there in big amounts! The goopy stuff between our skin cells is called extracellular matrix that consists mainly of lipids. And ceramides are about 50% of those lipids (the other important ones are cholesterol with 25% and fatty acids with 15%). 

Histidine - goodie

A semi-essential amino acid meaning that enough has to be eaten from it so that the body does not use up essential amino acids (that our body cannot produce itself) to synthesize it. It has an important role in regulating the immune defense, allergic reactions, and inflammatory processes in the body.

As for skincare, it's a skin moisturizer that might also protect from some skin infections

Arginine - goodie

A semi-essential (infants cannot synthesize it, but adults can) amino acid that is one of the primary building blocks of hair keratin and skin collagen. It's a natural moisturizing factor, a skin hydrator and might also help to speed up wound healing

Arginine usually has a positive charge (cationic) that makes it substantive to skin and hair (those are more negatively charged surfaces) and an excellent film former.  Thanks to the positive charge, it also creates a complex with AHAs (AHAs like to lose a hydrogen ion and be negatively charged, so the positive and the negative ions attract each other) that causes a "time-release AHA effect" and reduces the irritation associated with AHAs

Ceramide AP - goodie
Also-called: Ceramide 6 II | What-it-does: skin-identical ingredient

A type of ceramide that can be found naturally in the upper layer of the skin. Ceramides make up 50% of the goopy stuff that's between our skin cells and play a super important role in having a healthy skin barrier and keeping the skin hydrated. 

We have written way more about ceramides at ceramide 1, so click here to know more.

We don't have description for this ingredient yet.

Aspartic Acid - goodie

A non-essential amino acid  (important building block of collagen and elastin) that hydrates the skin. It is also used to set the pH of the cosmetic product (buffering).

Threonine - goodie

An essential amino acid that's also a key building block of collagen and elastin. When taken orally, it helps the digestive and intestinal tracts function more smoothly and also helps the absorption of nutrients. As for skincare, it is not clear what it does other than being a skin hydrator

Serine - goodie

Serine is an amino acid that most often comes to the formula as part of a moisturizing complex. It's a non-essential amino acid (meaning that our body can synthesize it) and serves as a water-binding ingredient.

In general, amino acids are great skincare ingredients that play an important role in proper skin hydration but there is not much info out there about what specifically serine can do for the skin.

Proline - goodie

A non-essential amino acid (meaning that our body can produce it) that's also one of the major building blocks of collagen. According to the Futurederm blog, it might be able to improve wrinkles when combined with other amino acids, glycine and leucine

Glycine - goodie

A non-essential amino acid (the building blocks of skin proteins, like collagen or elastin), that the body can produce itself, but its production decreases with age. When you put it all over your face, it works as a moisturizer and maybe more. 

According to great skincare blog Futurederm, glycine might help with wound healing and tissue repair and when used together with other amino acids, leucine and proline it might improve wrinkles

Alanine - goodie

A non-essential amino acid (a building block of skin proteins like collagen or elastin) that hydrates the skin.

Valine - goodie

An essential amino acid (a building block of skin proteins like collagen) that our body cannot produce itself but has to take from external sources, like diet. 

It's a branched chain amino acid that is claimed to enhance energy, increase endurance and aid in muscle tissue recovery and repair when taken as a supplement. It's not clear what valine does when you put it on the skin, but as all amino acids, it must be at least a great skin hydrator.

We don't have description for this ingredient yet.

What-it-does: moisturizer/humectant, solvent | Irritancy: 0 | Comedogenicity: 0
  • It's a helper ingredient that improves the freeze-thaw stability of products
  • It's also a solvent, humectant and to some extent a penetration enhancer
  • It has a bad reputation among natural cosmetics advocates but cosmetic scientists and toxicology experts do not agree (read more in the geeky details section)
Read all the geeky details about Propylene Glycol here >>

We don't have description for this ingredient yet.

Isoleucine - goodie

A branch-chained, essential amino acid that can be found in things like almond, cashew or soy protein. When taken orally it may promote protein synthesis. As for skincare - like all the amino acids - it's a skin-identical ingredient and moisturizer. It also seems to be useful as a barrier repair ingredient.  

Also-called: Rose Geranium Essential Oil | What-it-does: perfuming

The fragrant essential oil coming from the whole plant of Rose Geranium. It has a lovely scent with a mix of rose and citrus. 

Like most essential oils, it contains antioxidant and antimicrobial components, but the main ones are fragrant constituents (like geraniol and citronellol). Be careful with it, if your skin is sensitive. 

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

What-it-does: antioxidant

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

What-it-does: soothing

A copper salt (copper cation + gluconate anion) probably best known for promoting cellular regeneration and wound healing. It works mainly in the final healing phase that complements nicely with the wound healing abilities of its mineral salt sister, zinc gluconate

Other than that, copper is also involved in several enzyme systems: it is a cofactor for the antioxidant enzyme, superoxide dismutase and also a cofactor for the melanin stimulating enzyme, tyrosinase. This means that copper has some tan activating properties, though we think you should not be into tanning at all, as UV is so bad for the skin

We don't have description for this ingredient yet.

Glycerin - superstar
Also-called: Glycerol | What-it-does: skin-identical ingredient, moisturizer/humectant | Irritancy: 0 | Comedogenicity: 0
  • A natural moisturizer that’s also in our skin
  • A super common, safe, effective and cheap molecule used for more than 50 years
  • Not only a simple moisturizer but knows much more: keeps the skin lipids between our skin cells in a healthy (liquid crystal) state, protects against irritation, helps to restore barrier
  • Effective from as low as 3% with even more benefits for dry skin at higher concentrations up to 20-40%
  • High-glycerin moisturizers are awesome for treating severely dry skin
Read all the geeky details about Glycerin here >>

What-it-does: surfactant/cleansing, emulsifying | Irritancy: 0 | Comedogenicity: 0

We don't have description for this ingredient yet.

Ceramide NP - goodie
Also-called: Ceramide 3 | What-it-does: skin-identical ingredient

One of the many types of ceramides that can be found naturally in the upper layer of the skin. Ceramides make up about 50% of the goopy stuff that's between our skin cells and play a super important role in having a healthy skin barrier and keeping the skin hydrated. It works even better when combined with its pal, Ceramide 1.

We wrote way more about ceramides at ceramide 1, so click here to know more.

We don't have description for this ingredient yet.

What-it-does: perfuming

We don't have description for this ingredient yet.

Also-called: Grapefruit Peel Oil | What-it-does: perfuming

The essential oil coming from the rind of the grapefruit. In general, the main component of citrus peel oils is limonene (86-95% for grapefruit peel), a super common fragrant ingredient that makes everything smell nice (but counts as a frequent skin sensitizer).

Other than that, citrus peel also contains the problematic compound called furanocoumarin that makes them mildly phototoxic. In general, the more sour-bitter the fruit, the more problematic it is regarding phototoxicity: orange and clementine peel contain less of it while lemon, grapefruit, and bergamot contain some more. Be careful with it if it is in a product for daytime use.  

We don't have description for this ingredient yet.

Phenylalanine - goodie

An essential amino acid that the body cannot produce itself but has to take from the diet. Combined with UVA exposure, phenylalanine is used in the treatment of vitiligo (a pigmentation disorder where patches of the skin lose the pigment).

What-it-does: emollient

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

Citral - icky
What-it-does: perfuming

It’s a common fragrance ingredient that smells like lemon and has a bittersweet taste.  It can be found in many plant oils, e.g. lemon, orange, lime or lemongrass. 

It’s one of the “EU 26 fragrances” that has to be labelled separately (and cannot be simply included in the term “fragrance/perfume” on the label) because of allergen potential. Best to avoid if your skin is sensitive.

Limonene - icky
What-it-does: perfuming, solvent, deodorant

A super common and cheap fragrance ingredient. It's in many plants, e.g. rosemary, eucalyptus, lavender, lemongrass, peppermint and it's the main component (about 50-90%) of the peel oil of citrus fruits.

It does smell nice but the problem is that it oxidizes on air exposure and the resulting stuff is not good for the skin. Oxidized limonene can cause allergic contact dermatitis and counts as a frequent skin sensitizer

Linalool - icky
What-it-does: perfuming, deodorant

Linalool is a super common fragrance ingredient. It’s kind of everywhere - both in plants and in cosmetic products. It’s part of 200 natural oils including lavender, ylang-ylang, bergamot, jasmine, geranium and it can be found in 90-95% of prestige perfumes on the market. 

The problem with linalool is, that just like limonene it oxidises on air exposure and becomes allergenic. That’s why a product containing linalool that has been opened for several months is more likely to be allergenic than a fresh one.

Geraniol - icky
What-it-does: perfuming

Geraniol is a common fragrance ingredient. It smells like rose and can be found in rose oil or in small quantities in geranium, lemon and many other essential oils. 

Just like other similar fragrance ingredients (like linalool and limonene) geraniol also oxidises on air exposure and becomes allergenic. Best to avoid if you have sensitive skin.

What-it-does: perfuming

Citronellol is a very common fragrance ingredient with a nice rose-like odor. In the UK, it’s actually the third most often listed perfume on the ingredient lists. 

It can be naturally found in geranium oil (about 30%) or rose oil (about 25%). 

Eugenol - icky
What-it-does: perfuming

A colorless or yellowish oil that's used as a fragrance. It has a spicy scent and can be found for example in basil, clove or cinnamon oil.

A 2006 in-vitro  (made in the lab not on real people) study examined if clove oil is cytotoxic and found that not only clove oil but also its main constituent, eugenol is cytotoxic even at very low concentration (0.03%). It’s also one of the “EU 26 fragrances” that has to be labelled separately (and cannot be simply included in the term “fragrance/perfume” on the label) because of allergen potential. Best to avoid at least in leave-on products.

You may also want to take a look at...

what‑it‑does solvent
Normal (well kind of - it's purified and deionized) water. Usually the main solvent in cosmetic products. [more]
what‑it‑does solvent | moisturizer/humectant
A natural corn sugar derived glycol. It can be used to improve skin moisturization, as a solvent, to boost preservative efficacy or to influence the sensory properties of the end formula. [more]
what‑it‑does solvent
A type of glycol. Its main job is to be a solvent, but it has also very good antimicrobial properties and acts as a true preservative booster. [more]
what‑it‑does moisturizer/humectant | emollient
A handy multi-tasking ingredient that gives the skin a nice, soft feel and also boosts the effectiveness of other preservatives. [more]
what‑it‑does perfuming | solvent
A naturally occurring floral component with a delicate scent that can mask the odor of other raw materials. It also has remarkable antimicrobial and preservative boosting abilities.
what‑it‑does emollient | perfuming
A clear, slightly yellow, odorless oil  that's a very common, medium-spreading emollient. It makes the skin feel nice and smooth and works in a wide range of formulas.
what‑it‑does emulsifying
what‑it‑does soothing | emollient | moisturizer/humectant
Jojoba-derived emollient wax esters (fatty acid + fatty alcohol) that make your skin feel nice and smooth. [more]
what‑it‑does emulsifying
what‑it‑does emollient | viscosity controlling
irritancy, com. 2, 2
A fatty (the good, non-drying kind of) alcohol that makes your skin feel smooth and nice (emollient), helps to thicken up products and also helps water and oil to blend (emulsifier).
what‑it‑does emollient | solvent
what‑it‑does preservative
what‑it‑does emulsifying | surfactant/cleansing
An amino acid-based emulsifier that helps water and oil to mix and stay that way. It is considered as natural, environmentally friendly, and hypoallergenic.  [more]
what‑it‑does viscosity controlling
A super commonly used thickener and emulsion stabilizer. [more]
what‑it‑does anti-acne | moisturizer/humectant
A synergistic combination of Zinc and l-PCA that can reduce sebum production and limit the proliferation of evil acne-causing bacteria. A goodie for oily, acne-prone skin. [more]
what‑it‑does moisturizer/humectant
A silky clear liquid that has great moisturizing, skin protecting and film-forming properties on the skin. [more]
what‑it‑does moisturizer/humectant
A low-molecular-weight water-binding ingredient, that can help to moisturize deeper layers of skin or hair. [more]
what‑it‑does moisturizer/humectant
what‑it‑does perfuming
The essential oil coming from the fruit (probably the rind) of the bergamot orange.  It's a common top note in perfumes and contains (among others) fragrant compounds limonene (37%), linalyl acetate (30%) and linalool (8.8%).  A well-known issue with bergamot oil (apart from the fragrance allergens) is that it contains phototoxic  [more]
what‑it‑does emulsifying | surfactant/cleansing
A mildly viscous, amber-colored liquid that works as an emulsifier and surfactant. [more]
what‑it‑does emulsifying | surfactant/cleansing
what‑it‑does antioxidant | moisturizer/humectant
what‑it‑does perfuming
what‑it‑does antioxidant
what‑it‑does antioxidant | skin brightening | moisturizer/humectant
The essential oil coming from the flowers of bitter orange. Contains fragrant components that give it a nice sweet smell. [more]
what‑it‑does moisturizer/humectant
Glutamic acid is a little molecule and non-essential (our body can synthesize it) amino acid with the important job of being a neurotransmitter in the human body meaning that it helps your nervous system work correctly.  As for what it's doing in cosmetics, Glutamic acids' main thing (similar to other amino acids) is being a humectant moisturizer and skin-conditioning [more]
what‑it‑does antioxidant | moisturizer/humectant
what‑it‑does antioxidant | skin brightening
what‑it‑does anti-acne | soothing
A zinc salt known for its soothing and wound healing properties as well as for its anti-acne properties.  [more]
what‑it‑does perfuming
The essential oil coming from the sweet orange. Its main component is limonene (up to 97%), a super common fragrant ingredient that makes everything smell nice. [more]
what‑it‑does antioxidant | moisturizer/humectant
what‑it‑does antimicrobial/antibacterial | perfuming
When it comes to Tea Tree, the essential oil is the one that steals the show with its well-documented antimicrobial and anti-acne effects. The extract is not very well defined, and it probably contains the active components of the oil in much-reduced concentrations. Manufacturers still mention soothing, antimicrobial, purifying and antiseptic  [more]
what‑it‑does antioxidant | moisturizer/humectant
what‑it‑does skin-identical ingredient | emollient
irritancy, com. 0, 0
It's one of the important lipids that can be found naturally in the outer layer of the skin. About 25% of the goopy stuff between our skin cells consists of cholesterol. [more]
what‑it‑does skin-identical ingredient
Ceramides get quite a lot of hype recently and good news: there is a reason for that. But before we go into the details, let's just quickly define what the heck ceramides are: They are waxy lipids that can be found naturally in the outer layer of the skin (called stratum corneum - SC). [more]
what‑it‑does skin-identical ingredient | moisturizer/humectant
An amino acid that is important in regulating the immune defense and inflammatory processes in the body. It's a skin moisturizer that might protect from skin infections. [more]
what‑it‑does skin-identical ingredient
An amino acid that is one of the primary building blocks of hair keratin and skin collagen. It's a natural moisturizing factor and might also help to speed up wound healing.  [more]
what‑it‑does skin-identical ingredient
A type of ceramide that can be found naturally in the upper layer of the skin. Ceramides make up 50% of the goopy stuff that's between our skin cells and play a super important role in having a healthy skin barrier and keeping the skin hydrated.  We have written way more about ceramides at ceramide 1, so click here to know more. [more]
what‑it‑does skin-identical ingredient
A non-essential amino acid  (important building block of collagen and elastin) that hydrates the skin. [more]
what‑it‑does skin-identical ingredient
An essential amino acid (important building block of collagen and elastin) that hydrates the skin. [more]
what‑it‑does skin-identical ingredient
Serine is an amino acid that most often comes to the formula as part of a moisturizing complex. It's a non-essential amino acid (meaning that our body can synthesize it) and serves as a water-binding ingredient.In general, amino acids are great skincare ingredients that play an important role in proper skin hydration but there is not much info out there about what specifically serine can d [more]
what‑it‑does skin-identical ingredient
A non-essential amino acid (meaning that our body can produce it) that might be able to improve wrinkles combined with other amino acids, glycine and leucine. [more]
what‑it‑does skin-identical ingredient
An amino acid (the building blocks of skin proteins, like collagen) that hydrates the skin and might help wound healing and improve wrinkles. [more]
what‑it‑does skin-identical ingredient
A non-essential amino acid (a building block of skin proteins like collagen or elastin) that hydrates the skin.
what‑it‑does skin-identical ingredient
An essential amino acid (a building block of skin proteins like collagen) that is a skin hydrator. [more]
what‑it‑does moisturizer/humectant | solvent
irritancy, com. 0, 0
A common glycol that improves the freeze-thaw stability of products. It's also a solvent, humectant and to some extent a penetration enhancer. [more]
what‑it‑does skin-identical ingredient
An essential amino acid that hydrates the skin and might be also a barrier repair ingredient. [more]
what‑it‑does perfuming
The fragrant essential oil coming from the whole plant of Rose Geranium. It has a lovely scent with a mix of rose and citrus.  Like most essential oils, it contains antioxidant and antimicrobial components, but the main ones are fragrant constituents (like geraniol and citronellol). [more]
what‑it‑does antioxidant
what‑it‑does soothing
A copper salt that is known to promote cellular regeneration and also has some antioxidant and tan-activating properties. [more]
what‑it‑does surfactant/cleansing | emulsifying
what‑it‑does skin-identical ingredient | moisturizer/humectant
irritancy, com. 0, 0
A real oldie but a goodie. Great natural moisturizer and skin-identical ingredient that plays an important role in skin hydration and general skin health. [more]
what‑it‑does surfactant/cleansing | emulsifying
irritancy, com. 0, 0
what‑it‑does skin-identical ingredient
Ceramides make up 50% of the goopy stuff that's between our skin cells and play a super important role in having a healthy skin barrier and keeping the skin hydrated.  [more]
what‑it‑does perfuming
what‑it‑does perfuming
The essential oil coming from the rind of the grapefruit. Its main component (86-95%) is limonene, the super common fragrant ingredient. [more]
what‑it‑does skin-identical ingredient
An essential amino acid that is used in the treatment of vitiligo. [more]
what‑it‑does emollient
what‑it‑does perfuming | viscosity controlling
what‑it‑does perfuming
A common fragrance ingredient that smells like lemon. [more]
what‑it‑does perfuming | solvent
A super common fragrance ingredient found naturally in many plants including citrus peel oils, rosemary or lavender. It autoxidizes on air exposure and counts as a common skin sensitizer. [more]
what‑it‑does perfuming
A super common fragrance ingredient that can be found among others in lavender, ylang-ylang, bergamot or jasmine. The downside of it is that it oxidises on air exposure and might become allergenic. [more]
what‑it‑does perfuming
A common fragrance ingredient that smells like rose and can be found in rose oil. [more]
what‑it‑does perfuming
A common fragrance ingredient with a nice rose-like smell. [more]
what‑it‑does perfuming
A colorless or yellowish oil that's used as a fragrance with a spicy scent. [more]