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Castor oil is sourced from the castor bean plant native to tropical areas in Eastern Africa and the Mediterranean Basin. It is an age-old ingredient (it’s over 4,000 years old!) with many uses including as a shoe polish, food additive and motor lubricant. You would be reasonable to think that putting shoe polish on your face wouldn’t be the best idea, but it turns out castor oil has some unique properties that make it a stalwart in thick and gloss-giving formulas (think lipsticks and highlighters).
So what is so special about it? The answer is its main fatty acid, called ricinoleic acid (85-95%). Unlike other fatty acids, ricinoleic acid has an extra water-loving part (aka -OH group) on its fatty chain that gives Castor Oil several unique properties. First, it is thicker than other oils, then its solubility is different (e.g. dissolves in alcohol but not in mineral oil), and it allows all kinds of chemical modifications other oils do not, hence the lots of Castor oil-derived ingredients. It is also more glossy than other oils, in fact, it creates the highest gloss of all natural oils when applied to the skin. Other than that, it is a very effective emollient and occlusive that reduces skin moisture loss so it is quite common in smaller amounts in moisturizers.
While it is very unlikely (and this is true for pretty much every ingredient), cases of reactions to castor oil have been reported, so if your skin is sensitive, it never hurts to patch test.
The combination of glycerin + behenic acid that comes either in a fine powder or waxy solid form. Together with the di- and triglyceride of behenic acid, the trio has remarkable gelling properties helping cosmetic chemists to create ultra-soft and non-tacky waterfree gels. They also have great emulsion stabilizing properties, and work as high-performance compacting agents for makeup products that come in the form of pressed powders.
It's also vegetable origin, and Ecocert certified.
A super common emollient that makes your skin feel nice and smooth. It comes from coconut oil and glycerin, it’s light-textured, clear, odorless and non-greasy. It’s a nice ingredient that just feels good on the skin, is super well tolerated by every skin type and easy to formulate with. No wonder it’s popular.
It's the yellow, solid stuff that you probably know from beeswax candles. It's a natural material produced by honey bees to build their honeycomb.
As for skincare, it's used as an emollient and thickening agent. It's super common in lip balms and lipsticks.
We don't have description for this ingredient yet.
The extract coming from the coconut fruit. It is a similar thing to coconut water and fruit juice and is loaded with sugars, minerals, amino acids. It is also claimed to have vitalizing and energizing effects, and some smoothing, emollient and hydrating props.
If you are into coconut, we have more details at coconut water and coconut oil.
A hard wax coming from sunflower that has a high melting point and gives excellent thermal stability to the formulas. Similar to other waxes, it is used to stabilize products and give body to them, or to keep stick type formulas, such as lip balms, solid.
The oil coming from the seeds of the wild rose bush most common in the southern Andes in Chile (btw, Rosa Rubiginosa, Rosa Eglanteria and Rosa Mosqueta all refer to the same oil, however, the more commonly used Rosa Canina is a bit different). Similar to many other great plant oils, it is a nice nourishing and moisturizing oil loaded with fatty acids (linoleic acid - 44%, linolenic acid - 34% and oleic acid - 14%).
What makes rosehip oil a special snowflake among all the plant oils out there is that it also contains the miracle active, trans-retinoic acid, aka tretinoin. It is the main bioactive component of the oil and has all kinds of magic abilities including restoring and regenerating tissues (the oil is great for scars and burns), decreasing wrinkles, helping acne and even normalizing pore size.
Just one more note: a study found that the tretinoin content of rosehip seed oil greatly depends on the extraction method. The oil coming from cold pressing contained seven times more tretinoin (0.357 ml/l) than the oil from organic solvent extraction. Always go for the cold-pressed version!
We don't have description for this ingredient yet.
The oil coming from the seeds of the yellow flowered safflower plant. Similar to other plant oils, it's loaded with nourishing and moisturizing fatty acids: it's a high linoleic acid oil (70%) and has only smaller amounts of oleic acid (11%) (this might be great for acne-prone skin). It also contains antioxidant vitamin E (44mg/100g alpha-tocopherol).
- Primary fat-soluble antioxidant in our skin
- Significant photoprotection against UVB rays
- Vit C + Vit E work in synergy and provide great photoprotection
- Has emollient properties
- Easy to formulate, stable and relatively inexpensive
There is definitely some craze going on for coconut oil both in the healthy eating space (often claimed to be the healthiest oil to cook with but this is a topic for another site) and in the skin and hair care space.
We will talk here about the latter two and see why we might want to smear it all over ourselves. Chemically speaking, coconut oil has a unique fatty acid profile. Unlike many plant oils that mostly contain unsaturated fatty acids (fatty acids with double bonds and kinky structure such as linoleic or oleic), coconut oil is mostly saturated (fatty acids with single bonds only) and its most important fatty acid is Lauric Acid (about 50%). Saturated fatty acids have a linear structure that can stack nice and tight and hence they are normally solid at room temperature. Coconut oil melts around 25 °C so it is solid in the tub but melts on contact with the skin.
The saturated nature of coconut oil also means that it is a heavy-duty-oil ideal for dry skin types. A double-blind research confirmed that extra virgin coconut oil is as effective in treating xerosis (aka very dry skin) as mineral oil. Another study found that coconut oil is more effective than mineral oil in treating mild to moderate atopic dermatitis (aka eczema) in children.
So when it comes to dry skin, coconut oil is a goodie, no question there. The question is if it is good or bad for acne-prone skin. Its main fatty acid, Lauric Acid has some research showing that it is a promising ingredient against evil acne-causing bacteria, P. acnes but at the same time, both Lauric Acid and coconut oil have a very high comedogenic rating (4 out of 5). Though comedogenic ratings are not very reliable, anecdotal evidence (i.e. people commenting in forums) shows that people have mixed experiences. While some claim that it worked wonders on their acne others say that it gave them serious blackheads and zits. Try it at your own risk.
As for hair care, coconut oil has pretty solid research showing that it can penetrate into the hair very well (better than mineral oil and sunflower oil) and it can prevent hair protein loss as well as combing damage. If you have problems with damaged hair, split ends, coconut oil is worth trying as a pre- or/and post-wash treatment. Labmuffin has an awesome blogpost explaining in more detail why coconut oil is good for your hair.
A couple of other things worth mentioning: coconut oil might help with wound healing (promising animal study), it has some antifungal activity (against dermatophytes that cause the thing known as ringworm) and it also works as an insect repellent against black flies.
Overall, coconut oil is definitely a goodie for the hair and dry skin. If that warrants for the magic oil status it enjoys, we don't know.
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
The extract derived from Prickly Pear, a cactus native to Mexico. It is well-known for its soothing and hydrating properties. Read our shiny explanation about Opuntia Ficus-Indica here >>
We don't have description for this ingredient yet.
Theobroma means "food of the gods" in Greek though probably "treat of the people" would be more spot on. The cacao fruits and especially the seeds in it need no introduction as everyone knows them as the magical raw material of the magical sweet treat, chocolate (the flavour is composed of more than 1200(!) substances, and the exact chemical nature of it is not really understood, so it's indeed magic. :)).
As for skincare, cocoa butter counts as a rich emollient that can moisturize and nourish even the driest skin (think chapped hands or lips). It's solid at room temperature and melts nicely when you smear it on. It's loaded with good-for-the-skin things: it contains fatty acids, mainly oleic (35%), stearic (34%), and palmitic (25%) and it also has antioxidant vitamin E and polyphenols.
An ex-vivo (made on human skin but not on real people) study examined the cocoa polyphenols and found that 0.5-0.75% of them improved skin tone and elasticity and had a similarly positive impact on GAGs (important natural moisturizing factors in the skin) and collagen synthesis than a commercial high-end moisturizer (it was an Estee Lauder one).
All in all, cocoa butter is a goodie, especially for very dry skin.
Astragalus Membranaceus, or Huangqi as the Chinese call it, is one of their most important medicinal herbs that is traditionally used to strengthen "qi", the body’s life force. It has a bunch of magic abilities including tonic, liver-protecting, immunomodulating, antihyperglycemic, anti-inflammatory, antioxidant, and antiviral properties.
Modern research does prove that Huangqi is a valuable medicinal herb and contains plenty of bioactive compounds such as saponins, flavonoids, and polysaccharides. As for skincare and Huangqi, it is well known and used for its general tonic and skin reinforcing properties, as well as for its anti-inflammatory and antioxidant action.
On top of that, we also found a manufacturer claiming that Astragalus Membranaceus Root Extract combines anti-aging and anti-blemish properties so it is especially useful for aging, acne-prone skin. In their in-vivo (made on real people) studies, 2% of liposomal Huangqi increased skin hydration, firmness, and smoothness by 20% after 14 days and decreased "blemish-prone skin signs" by 10-15% after 42 days.
Thanks to Nivea, Q10 is a pretty well-known ingredient and the fame and Beiersdorf's (the parent company of Nivea) obsession with it are not for no reason. It's an antioxidant found naturally in human cells where it plays a big role in energy production.
In fact, it's so important for energy production that if taken as an oral supplement it has a caffeine-like effect and if taken at night you will probably not sleep very well (so you should take it in the morning). Q10 supplementation is not a bad idea: it not only gives you energy but research also shows that oral Q10 increases the Q10 level of the skin (of course, it decreases with age like pretty much every good thing in the skin) and may help to reduce wrinkles. If you are not for supplements, dietary sources include fish, spinach, and nuts.
As for skincare, Q10 comes in the form of a yellow, oil-soluble powder that's shown to absorb into the upper layer of the skin and act there like an awesome antioxidant. It not only has preventative effects but might also be able to reduce the depth of wrinkles, though 0.3% Q10 was used in the study that counts as really high (products containing that much should be very yellow!).
Mustic gum is an aromatic resin coming from the bark of a tree that grows on the Greek island of Chios. It was traditionally used as a chewing gum to clean the teeth and freshen the breath thanks to its anti-microbial properties.
As for modern skincare, it is the active ingredient in a skin care complex trade named PoreAway, that is claimed to tighten dilated pores and reduce shine. It works by blocking 5α reductase type I, an enzyme that has an important role in the sebum-producing process (by converting testosterone to dihydrotestosterone, aka DHT, that is the main sebum producing hormone in the skin).
Do not expect miracles though: according to the in-vivo test conducted by the manufacturer, 2% PoreAway refined pores only by 8% after 14 days and 15% after 28 days. We are not sure if this is a change that you can really feel and see on your skin, or if it's just a "statistically significant change" that can be measured in the lab.
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 have to admit that Algae Extract is not our favorite ingredient name. It does comply with the INCI standard (the official list about how ingredients on the product labels have to be called, the thing we help you to decode here :)), but there are about 20 000 different kinds of algae and an extract from them can be made in another 10 000 ways.
So, Algae Extract can be anything from La Mer's "Miracle Broth" to a simple brown algae extract that helps to smooth the hair. The official description in the Europiean Cosmetic Ingredient listing is this: "an extract of various species of Algae; Extract of the Seaweed, Fucus vesiculosus, Furaceae". Its official functions include being a humectant (helps skin to attract water), emollient (makes skin feel smooth and nice) and skin conditioner (a catchall phrase for saying it does something good for the skin).
A 2015 research paper on the potential of uses of algae in cosmetics summarizes that algae are rich sources of biologically active metabolites including antioxidants, anti-inflammatory agents, alginates, polysaccharides, and carotenoids. Currently, algae extracts are mostly used as moisturizing and thickening agents, but algae also have great potential to combat skin aging, pigmentation as well as working as an antimicrobial.
We have also browsed through Prospector to see what manufacturers say about their algae. There is, for example, an algae extract trade-named Lanablue that comes from blue-green algae (green algae is rare, less than 1% of the total macroalgae in the world) and is claimed to have retinoid like effects (i.e. reduce wrinkles, smooth skin) but without the side effects (though it seems now that the INCI name of Lanablue was changed to Aphanizomenon Flos-Aquae Extract).
There is another algae extract from another manufacturer that comes from red algae (much more common, about 40% of total macroalgae worldwide) and is claimed to have not only moisturizing but also skin smoothing and densifying effects.
Here is a brown algae extract (the most common type, about 59% of macroalgae), also just called Algae Extract on the product label that is simply claimed to be a free radical scavenger, aka antioxidant. These were just three random examples from three manufacturers all called Algae extract even though they all come from different algae with different claims.
Anyhow, the point is this; there are tons of different types of Algae Extracts out there. Unless the brand tells you what they use, it's impossible to know for sure. The most probable scenario for the Alge Extract is that it works as a moisturizer and emollient and it might have some additional anti-aging properties.
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.
A form of skincare superstar, vitamin C. Even though we are massive vitamin C fans, Ascorbyl Palmitate (AP) is our least favorite. (Btw, if you do not know what the big deal with vitamin C is then you are missing out. You must go and read our geeky details about it.)
So, AP is one of the attempts by the cosmetics industry to solve the stability issues with vitamin C while preserving its benefits, but it seems to fall short on several things.
What's the problem?
Firstly, it's stability is only similar to that of pure ascorbic acid (AA), which means it is not really stable. A great study in the Journal of Cosmetic Dermatology compared a bunch of vitamin C derivatives and this derivative was the only one where the study said in terms of stability that it's "similar to AA". Not really that good.
Second, a study that examined the skin absorption of vitamin C found that ascorbyl palmitate did not increase the skin levels of AA. This does not mean that ascorbyl palmitate cannot penetrate the skin (because it can, it's oil soluble and the skin likes to absorb oil soluble things) but this means that it's questionable if ascorbyl palmitate can be converted into pure Vit C in the skin. Even if it can be converted, the palmitate part of the molecule is more than the half of it, so the efficacy will not be good and we have never seen a serum that contains a decent (and proudly disclosed) amount of AP. We are highly skeptical what effect a tiny amount of AP has in a formula.
Third, another study that wanted to examine the antioxidant properties of AP was surprised to find that even though AP does have nice antioxidant properties; following UVB radiation (the same one that comes from the sun) it also promotes lipid peroxidation and cytotoxicity. It was only an in-vitro study meaning that it was done on cell cultures and not on real people, but still, this also does not support the use of AP too much.
The only good thing we can write about Ascorbyl Palmitate is that there is an in-vitro (made in the lab, not on real people) study showing that it might be able to boost collagen production.
Regarding the skin-brightening properties of pure vitamin C, this is another magic property AP does not have, or at least there is no data, not even in-vitro, about it.
Overall, Ascorbyl Palmitate is our least favorite vitamin C derivative. It is there in lots of products in tiny amounts (honestly, we do not really understand why), however, we do not know about any vitamin C serum featuring AP in high amounts. That is probably no coincidence. If you are into vitamin C, you can take a look at more promising derivatives here.
An emollient plant oil coming from the Sacha Inchi plant from the Colombian Amazon.
Similar to other plant oils, it's loaded with nourishing and moisturizing fatty acids: it's especially rich in α-Linolenic acid (42-49%) and linoleic acid (32-38%) and contains less oleic acid (9-14%). It also contains a decent amount of antioxidant vitamin E (200 mg/kg).
We don't have description for this ingredient yet.
The oil coming from the pulp of the sea buckthorn berry. It has a pretty unique fatty acid composition: 65% is a combination of the rare Omega-7, aka palmitoleic acid and the more common palmitic acid. Fatty acids give the oil nice moisturizing and skin-protecting abilities.
But that's not all the goodness of sea buckthorn oil. It contains antioxidant superstar, Vitamin E (in multiple forms), antioxidant (and orange color giving) pigments beta-carotene and lycopene, as well as skin-soothing and replenishing beta-sitosterol.
Btw, used undiluted, it will make your skin orange.
All in all, a goodie emollient plant oil.
When it comes to cucumber and skin care, cucumber fruit extract is the one that steals the show for its soothing and moisturizing properties. But cucumber also has seeds and these seeds contain oil that has nice fatty acids and emollient properties, similar to many other plant oils.
Cucumber oil is a high linoleic acid (60-69%) oil that also has a fair amount of oleic acid (9-20%). It also contains antioxidant vitamin E, phytosterols and some trace minerals such as potassium. It is a very light oil that is absorbed easily into the skin. It is described as an excellent oil for moisturization formulations.
The oil coming from the seeds of the nice, little, yellow-flowered plant called Evening Primrose. Similar to other plant oils, it's loaded with nourishing and moisturizing fatty acids. It's a very rich source of linoleic acid (66-76%), and also contains the soothing and healing superstar fatty acid, gamma-linolenic acid (aka GLA, 7-12%) (Btw, the richest known source of GLA is the borage oil, but evening primrose still counts as a very good source of it). It also contains oleic acid, but not too much around 6-15%.
Since the 1980's, EPO is a well-known food supplement and there are quite a lot of studies examining what happens if you take it orally. It seems to be helpful with a bunch of things: atopic dermatitis, dry eyes, brittle nails, sunburn and even acne.
As for the skin, it's a great hydrating plant oil, that can also reduce inflammation and irritation. It's a superb healing agent that can truly help dry skin, not just on the surface by covering it (and not letting water to evaporate) but by initiating structural changes within the skin. If that's not enough, it also helps skin cell regeneration.
All in all, a real goodie especially for dry, easily irritated skin.
We don't have description for this ingredient yet.
A beautiful golden-yellow oil coming from the Camellia tree. It's a 5 -10 meters high tree with spectacular white flowers native to Asia. It's pretty common there and also used as cooking oil or salad dressing. Sometimes Camellia oil is referred to as "the olive oil of Asia".
So what can it do for the skin? Similar to many other great non-fragrant plant oils, it's a great emollient and moisturising oil for dry skin. It's light in texture, absorbs fast into the skin and leaves it soft and supple.
It contains a bunch of good-for-the-skin stuff: it's very rich (70-85%) in nourishing and moisturising fatty acid, oleic acid (though if you are acne-prone be careful with oleic acid), contains significant amount of antioxidant vitamin E (0.15%) as well as great emollient and antioxidant squalene (2-3%).
All in all, a skin goodie especially for dry skin.
Jojoba is a drought resistant evergreen shrub native to South-western North America. It's known and grown for jojoba oil, the golden yellow liquid coming from the seeds (about 50% of the weight of the seeds will be oil).
At first glance, it seems like your average emollient plant oil: it looks like an oil and it's nourishing and moisturizing to the skin but if we dig a bit deeper, it turns out that jojoba oil is really special and unique: technically - or rather chemically - it's not an oil but a wax ester (and calling it an oil is kind of sloppy).
So what the heck is a wax ester and why is that important anyway? Well, to understand what a wax ester is, you first have to know that oils are chemically triglycerides: one glycerin + three fatty acids attached to it. The fatty acids attached to the glycerin vary and thus we have many kinds of oils, but they are all triglycerides. Mother Nature created triglycerides to be easily hydrolyzed (be broken down to a glycerin + 3 fatty acid molecules) and oxidized (the fatty acid is broken down into small parts) - this happens basically when we eat fats or oils and our body generates energy from it.
Mother Nature also created wax esters but for a totally different purpose. Chemically, a wax ester is a fatty acid + a fatty alcohol, one long molecule. Wax esters are on the outer surface of several plant leaves to give them environmental protection. 25-30% of human sebum is also wax esters to give us people environmental protection.
So being a wax ester results in a couple of unique properties: First, jojoba oil is extremely stable. Like crazy stable. Even if you heat it to 370 C (698 F) for 96 hours, it does not budge. (Many plant oils tend to go off pretty quickly). If you have some pure jojoba oil at home, you should be fine using it for years.
Second, jojoba oil is the most similar to human sebum (both being wax esters), and the two are completely miscible. Acne.org has this not fully proven theory that thanks to this, jojoba might be able to "trick" the skin into thinking it has already produced enough sebum, so it might have "skin balancing" properties for oily skin.
Third, jojoba oil moisturizes the skin through a unique dual action: on the one hand, it mixes with sebum and forms a thin, non-greasy, semi-occlusive layer; on the other hand, it absorbs into the skin through pores and hair follicles then diffuses into the intercellular spaces of the outer layer of the skin to make it soft and supple.
On balance, the point is this: in contrast to real plant oils, wax esters were designed by Mother Nature to stay on the surface and form a protective, moisturizing barrier and jojoba oil being a wax ester is uniquely excellent at doing that.
A nice yellow flower living in the mountains that's famously used to treat bruisings. Its role in skincare is questionable though. Read more here >>
When it comes to borage and skincare, the seed oil is the one that's usually mentioned thanks to its uniquely high gamma-linolenic acid content.
But the leaves are not useless either: they contain great antioxidant compounds, like polyphenols and flavonoids and show significant free-radical scavenging activity (though much less than vitamin C and similar to the synthetic antioxidant, BHT).
The extract coming from the popular garden plant Calendula or Marigold. According to manufacturer info, it's used for many centuries for its exceptional healing powers and is particularly remarkable in the treatment of wounds. It contains flavonoids that give the plant anti-inflammatory and antioxidant properties.
We don't have description for this ingredient yet.
The extract coming from the leaves and/or blossoms of Meadowsweet, a native to Europe plant that likes to grow in damp places such as meadows or the banks of streams.
It's main "skincare thing" is that it contains salicylic acid derivatives that give the extract anti-inflammatory properties. It also has tannins that make Spiraea Ulmaria Extract astringent, as well as spiraeoside that has anti-cellulitic properties.
You probably know olive oil from the kitchen as a great and healthy option for salad dressing but it's also a great and healthy option to moisturize and nourish the skin, especially if it's on the dry side.
Similar to other emollient plant oils, it's loaded with nourishing fatty acids: oleic is the main component (55-83%), and also contains linoleic (3.5-20%) and palmitic acids (7-20%). It also contains antioxidant polyphenols, tocopherols (types of vitamin E) and carotenoids and it's one of the best plant sources of skin-identical emollient, Squalene.
Overall, a great option for dry skin but less so for acne-prone or damaged skin.
We don't have description for this ingredient yet.
A vegetable wax coming from the leaves of the Brazilian tropical palm tree, Copernicia cerifera. Similar to other waxes, it is used to stabilize and give body to products, or to keep stick type formulas solid. It is the hardest natural wax with a high melting point (around 85C) and high gloss making it a great wax choice for lip products.
We don't have description for this ingredient yet.
A colorless liquid used in small amounts as a so-called masking ingredient, meaning it can hide the natural not-so-nice smell of other cosmetic ingredients. It has a nice rose-like scent and can be found in several essential oils such as rose, neroli or geranium. It also has some antimicrobial activity and can boost the performance of traditional preservatives.
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.
A study made in the UK with 483 people tested the allergic reaction to 3% oxidised linalool and 2.3% had positive test results.
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.
A common fragrance ingredient that has a faint sweet balsamic smell. It can also be a solvent and can fight against microbes and insects very well.
It's one of the “EU 26 fragrances” that has to be labelled separately because of allergen potential. Best to avoid if your skin is sensitive.
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.
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.
It's one of those things that help your cosmetics not to go wrong too soon, aka a preservative. It can be naturally found in fruits and teas but can also be made synthetically.
No matter the origin, in small amounts (up to 1%) it’s a nice, gentle preservative. Has to be combined with some other nice preservatives, like potassium sorbate to be broad spectrum enough.
In high amounts, it can be a skin irritant, but don’t worry, it’s never used in high amounts.
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.
Limonene's nr1 function is definitely being a fragrance component, but there are several studies showing that it's also a penetration enhancer, mainly for oil-loving components.
All in all, limonene has some pros and cons, but - especially if your skin is sensitive - the cons probably outweigh the pros.
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| what‑it‑does | emollient | perfuming |
| irritancy, com. | 0, 0-1 |
| what‑it‑does | emollient | emulsifying |
| what‑it‑does | emollient |
| what‑it‑does | emollient |
| what‑it‑does | emollient | viscosity controlling | emulsifying | perfuming |
| irritancy, com. | 0, 0-2 |
| what‑it‑does | emollient | solvent |
| what‑it‑does | emollient |
| what‑it‑does | emollient |
| what‑it‑does | antioxidant | emollient |
| what‑it‑does | antioxidant | emollient |
| irritancy, com. | 0, 0-2 |
| what‑it‑does | antioxidant |
| irritancy, com. | 0-3, 0-3 |
| what‑it‑does | emollient | perfuming |
| irritancy, com. | 0, 4 |
| what‑it‑does | soothing |
| what‑it‑does | emollient |
| irritancy, com. | 0, 4 |
| what‑it‑does | antioxidant | emollient |
| what‑it‑does | antioxidant |
| what‑it‑does | perfuming |
| what‑it‑does | antimicrobial/antibacterial |
| what‑it‑does | emollient | moisturizer/humectant |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | antioxidant |
| irritancy, com. | 0, 2 |
| what‑it‑does | antioxidant | emollient | moisturizer/humectant |
| what‑it‑does | antioxidant | emollient |
| what‑it‑does | emollient |
| what‑it‑does | soothing | emollient |
| irritancy, com. | 2, 3 |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | emollient |
| what‑it‑does | emollient |
| irritancy, com. | 0, 0-2 |
| what‑it‑does | antioxidant |
| what‑it‑does | soothing | antioxidant | perfuming |
| what‑it‑does | soothing |
| what‑it‑does | antioxidant | emollient |
| irritancy, com. | 0, 0-2 |
| what‑it‑does | emollient |
| irritancy, com. | 0, 3 |
| what‑it‑does | emollient |
| irritancy, com. | 0, 1 |
| what‑it‑does | perfuming |
| what‑it‑does | perfuming |
| what‑it‑does | solvent | perfuming | antimicrobial/antibacterial |
| what‑it‑does | perfuming |
| what‑it‑does | perfuming |
| what‑it‑does | preservative | perfuming | solvent | viscosity controlling |
| what‑it‑does | perfuming | solvent |