Smooth.again
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Kevin Murphy Smooth.againIngredients explained
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.
Once inside the skin, it hydrates, but not from the outside - putting pure water on the skin (hello long baths!) is drying.
One more thing: the water used in cosmetics is purified and deionized (it means that almost all of the mineral ions inside it is removed). Like this, the products can stay more stable over time.
We don't have description for this ingredient yet.
An extremely common multitasker ingredient that gives your skin a nice soft feel (emollient) and gives body to creams and lotions. It also helps to stabilize oil-water mixes (emulsions), though it does not function as an emulsifier in itself. Its typical use level in most cream type formulas is 2-3%.
It’s a so-called fatty alcohol, a mix of cetyl and stearyl alcohol, other two emollient fatty alcohols. Though chemically speaking, it is alcohol (as in, it has an -OH group in its molecule), its properties are totally different from the properties of low molecular weight or drying alcohols such as denat. alcohol. Fatty alcohols have a long oil-soluble (and thus emollient) tail part that makes them absolutely non-drying and non-irritating and are totally ok for the skin.
A cationic polymer molecule (a big molecule with repeated subunits and a positive charge) that acts both as a film-former and conditioning ingredient as well as a thickening agent.
An easy-to-formulate, commonly used, nice to have ingredient that’s also called pro-vitamin B5. As you might guess from the “pro” part, it’s a precursor to vitamin B5 (whose fancy name is pantothenic acid).
Its main job in skincare products is to moisturise the skin. It’s a humectant meaning that it can help the skin to attract water and then hold onto it. There is also research showing that panthenol can help our skin to produce more lovely lipids that are important for a strong and healthy skin barrier.
Another great thing about panthenol is that it has anti-inflammatory and skin protecting abilities. A study shows that it can reduce the irritation caused by less-nice other ingredients (e.g. fragrance, preservatives or chemical sunscreens) in the product.
Research also shows that it might be useful for wound healing as it promotes fibroblast (nice type of cells in our skin that produce skin-firming collagen) proliferation.
If that wasn’t enough panthenol is also useful in nail and hair care products. A study shows that a nail treatment liquide with 2% panthenol could effectively get into the nail and significantly increase the hydration of it.
As for the hair the hydration effect is also true there. Panthenol might make your hair softer, more elastic and helps to comb your hair more easily.
- 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
- Green tea is one of the most researched natural ingredients
- The active parts are called polyphenols, or more precisely catechins (EGCG being the most abundant and most active catechin)
- There can be huge quality differences between green tea extracts. The good ones contain 50-90% catechins (and often make the product brown and give it a distinctive smell)
- Green tea is proven to be a great antioxidant, UV protectant, anti-inflammatory, anticarcinogenic and antimicrobial
- Because of these awesome properties green tea is a great choice for anti-aging and also for skin diseases including rosacea, acne and atopic dermatitis
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.
Baobab is a really big, iconic tree native to Africa (here is a nice image of it). It's the largest succulent plant in the world and almost all parts of it have traditional medicinal uses in Africa.
The seed oil, similar to other plant oils, is loaded with things that are good-for-the-skin: it contains skin regenerating vitamin A, antioxidant vitamin E, and vitamin D3 that helps with calcium absorption. It's rich in nourishing fatty acids oleic (30-40%), linoleic (24-34%) and palmitic (18-30%).
Its moisturizing benefits are impressive, it absorbed into the skin quickly and might even improve skin elasticity. A great oil for drier skin types and excellent for eczema and psoriasis.
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.
We don't have description for this ingredient yet.
This is a cool looking fruit coming from the Australian sub-tropical rainforests. Caviar lime really is the perfect name for it. You have to click here and look at it.
As for skincare, we could not find too much info about it, but this manufacturer claims that it's a source of AHAs and can gently exfoliate the skin for a smoother, brighter and even skin complexion.
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.
The emollient plant oil coming from the soybean. It is considered to be a nice, cost-effective base oil with moisturizing properties. As for its fatty acid profile, it contains 48-59% barrier-repairing linoleic acid, 17-30% nourishing oleic acid and also some (4.5-11%) potentially anti-inflammatory linolenic acid.
The emollient plant oil coming from the seeds of Crambe Abyssinica, a not very well-known plant native to the Ethiopian Highlands. It has a unique fatty acid profile and contains high amounts of erucic acid (50-65%), a 22 carbon long unsaturated fatty acid.
The oil is described as having an elegant, silky and cushioning skin feel, kind of silicone-like. Also ideal for hair-care as it gives slip, softness, and shine to the hair.
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.
The complication is that glutamic acid has two distinct forms, L-glutamic acid and D-glutamic acid, that are the mirror images of each other (think of it like your left and right hand). Studies show that a topical application of L-glutamic acid on damaged skin delayed skin repair, while D-glutamic acid application sped up skin repair. As both forms are used by the industry, it is a bit uncertain what you are getting with just glutamic acid on the ingredient list (but if it is a Shiseido group product, it is probably the goodie D-form :)).
Other than that, Glutamic acid can also be used as a pH adjuster and can be processed via biological pathways into pyrrolidone carboxylic acid, the sodium salt of which is a goodie and one of your skin’s natural moisturizing factors.
We don't have description for this ingredient yet.
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.
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).
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.
BTW, it's also a building block of a bunch of important and famous peptides, including copper-tripeptide-1, palmitoyl tripeptide-1 or palmitoyl hexapeptide-12.
A non-essential amino acid (a building block of skin proteins like collagen or elastin) that hydrates the skin.
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.
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.
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
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.
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.
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).
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.
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
PCA stands for Pyrrolidone Carboxylic Acid and though it might not sound like it, it is a thing that can be found naturally in our skin. The sodium salt form of PCA is an important skin-identical ingredient and great natural moisturizer that helps the skin to hold onto water and stay nicely hydrated.
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.
The sodium salt of lactic acid. It's a great skin moisturizer and also used to regulate the pH value of the cosmetic formula. It's a natural ingredient approved by both ECOCERT and COSMOS.
PCA stands for Pyrrolidone Carboxylic Acid and though it might not sound like it, it is a thing that can be found naturally in our skin. In fact, after amino acids, it is the second biggest NMF component of the skin with 12% being PCA of the NMF composition of normal skin. So similar to other NMFs, it's a skin goodie that helps the skin to hold onto water and stay nicely hydrated.
A three amino acid peptide where the famous collagen fragment, Tripeptide-1, aka GHK is combined with Biotin, the well-known supplement for stronger nails and hairs. The result of the combination is Biotinoyl Tripeptide-1, a peptide claimed to be helpful for reducing hair loss and for making the eyelashes appear longer, fuller, and stronger.
As for proof, the manufacturer did some in-vitro (made in test tubes) studies that show that our molecule can promote hair bulb keratinocyte proliferation and also helps optimal hair anchorage by stimulating the synthesis and organization of the adhesion molecules laminin 5 and collagen IV. This means that our peptide might help the hair to be stronger and to stay longer in its place, though these are only in vitro results that might or might not translate to real-world use.
As for a clinical, made on real people study, the manufacturer did one for eyelash growth with 30 volunteers. Using a mascara with 2% of SpecPed LashLD (trade name for the diluted, buyable version of Biotinoyl Tripeptide-1), the lashes got longer by 17% and thicker by 19% after 30 days.
We don't have description for this ingredient yet.
- 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
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.
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.
Butylene glycol, or let’s just call it BG, is a multi-tasking colorless, syrupy liquid. It’s a great pick for creating a nice feeling product.
BG’s main job is usually to be a solvent for the other ingredients. Other tasks include helping the product to absorb faster and deeper into the skin (penetration enhancer), making the product spread nicely over the skin (slip agent), and attracting water (humectant) into the skin.
It’s an ingredient whose safety hasn’t been questioned so far by anyone (at least not that we know about). BG is approved by Ecocert and is also used enthusiastically in natural products. BTW, it’s also a food additive.
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.
A clear, colorless, almost odorless oil that spreads nicely and easily and gives a velvet dry skin feel. It is good friends with sunscreen agents and helps to solubilize them. Also, it makes sunscreens feel lighter and spread easier.
A helper ingredient that usually comes to the formula coupled with PEG-40 Hydrogenated Castor Oil. The two together work as surfactants and oil solubilizers. It's a non-sticky duo that works at low concentration and is often used to solubilize fragrance components into water-based formulas.
One of the 9 types of ceramides that can be found naturally in the upper layer of the skin. Ceramides make up a big part (about 50%) of the goopy stuff that's between our skin cells (called extracellular matrix) and play a super important role in having a healthy skin barrier and keeping the skin hydrated.
We wrote way more about ceramides at ceramide 1, so click here to know more.
A light emollient ester (C8-10 fatty acids connected to C12-18 fatty alcohols) that absorbs quickly and leaves a dry but silky finish on the skin. In terms of skin feel, it is similar to Dicaprylyl Carbonate, another commonly used light emollient.
A clear, almost colorless (or slightly yellowish) oily liquid (an ester to be precise) that's used as a medium spreading emollient. It gives skin a nice and smooth after-feel and it's very good at reducing oiliness or greasiness coming from other heavier oils in the formula.
Propylene Glycol Dicaprylate/Dicaprate is an emollient that leaves a light, non-oily smooth and velvet skin sensation. According to manufacturer info it's also great at dispersing and dissolving pigments and sunscreen actives. Most often you will meet this guy in light moisturizers, sunscreens or makeup products.
We don't have description for this ingredient yet.
A 100% vegetable origin, biodegradable, mild cleansing agent that gives moderate to high amount of foam. It's happy to work together with other surfactants (in general, that helps to create milder formulas).
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.
A common little helper ingredient that helps water and oil to mix together, aka emulsifier.
A clear, oil-soluble, "cosmetically-elegant" liquid that is the most commonly used chemical sunscreen. It absorbs UVB radiation (at wavelengths: 280-320 nm) with a peak protection at 310nm.
It only protects against UVB and not UVA rays (the 320-400 nm range) – so always choose products that contain other sunscreens too. It is not very stable either, when exposed to sunlight, it kind of breaks down and loses its effectiveness (not instantly, but over time - it loses 10% of its SPF protection ability within 35 mins). To make it more stable it can be - and should be - combined with other sunscreen agents to give stable and broad-spectrum protection (the new generation sunscreen agent, Tinosorb S is a particularly good one for that).
Regarding safety, there are also some concerns around Octinoxate. In vitro (made in the lab not on real people) and animal studies have shown that it may produce hormonal (estrogen-like) effects. Do not panic, the studies were not conducted under real life conditions on real human people, so it is probably over-cautious to avoid Octinoxate altogether. However, if you are pregnant or a small child (under 2 yrs. old), choose a physical (zinc oxide/titanium dioxide) or new-generation Tinosorb based sunscreen, just to be on the super-safe side. :)
Overall, Ethylhexyl Methoxycinnamate is an old-school chemical sunscreen agent. There are plenty of better options for sun protection today, but it is considered "safe as used" (and sunscreens are pretty well regulated) and it is available worldwide (can be used up to 10% in the EU and up to 7.5% in the US).
A silicone-based, chemical sunscreen agent that protects the skin in the UVB range (290-320 nm) with a peak absorbance at 312 nm. It is a colorless to pale yellow liquid with nice and non-shiny (at least compared to most other sunscreens) sensorial properties.
It is a pretty good team player and can stabilize the famously unstable UVA filter, avobenzone and works especially well with Ensulizole to achieve high SPF protection. It is approved up to 10% as a sunscreen filter in the EU and most parts of the world, except for the United States.
We don't have description for this ingredient yet.
It's the acronym for Butylated Hydroxy Toluene. It's a common synthetic antioxidant that's used as a preservative.
There is some controversy around BHT. It's not a new ingredient, it has been used both as a food and cosmetics additive since the 1970s. Plenty of studies tried to examine if it's a carcinogen or not. This Truth in Aging article details the situation and also writes that all these studies examine BHT when taken orally.
As for cosmetics, the CIR (Cosmetic Ingredient Review) concluded that the amount of BHT used in cosmetic products is low (usually around 0.01-0.1%), it does not penetrate skin far enough to be absorbed into the bloodstream and it is safe to use in cosmetics.
It’s pretty much the current IT-preservative. It’s safe and gentle, but even more importantly, it’s not a feared-by-everyone-mostly-without-scientific-reason paraben.
It’s not something new: it was introduced around 1950 and today it can be used up to 1% worldwide. It can be found in nature - in green tea - but the version used in cosmetics is synthetic.
Other than having a good safety profile and being quite gentle to the skin it has some other advantages too. It can be used in many types of formulations as it has great thermal stability (can be heated up to 85°C) and works on a wide range of pH levels (ph 3-10).
It’s often used together with ethylhexylglycerin as it nicely improves the preservative activity of phenoxyethanol.
If you have spotted ethylhexylglycerin on the ingredient list, most probably you will see there also the current IT-preservative, phenoxyethanol. They are good friends because ethylhexylglycerin can boost the effectiveness of phenoxyethanol (and other preservatives) and as an added bonus it feels nice on the skin too.
Also, it's an effective deodorant and a medium spreading emollient.
A little helper ingredient that works as a preservative. It works against bacteria and some species of fungi and yeast. It's often combined with IT-preservative, phenoxyethanol.
A mild, natural preservative that usually comes to the formula together with its other mild preservative friends, such as Benzoic Acid and/or Dehydroacetic Acid. Btw, it's also used as a food preservative.
An Ecocert-approved, natural preservative that counts as gentle and non-irritating to the skin. Usually, it comes to the formula as part of a preservative blend as it's not enough on its own.
It's one of those things that help your cosmetics not to go wrong too soon, aka a preservative. It’s not a strong one and doesn’t really work against bacteria, but more against mold and yeast. To do that it has to break down to its active form, sorbic acid. For that to happen, there has to be water in the product and the right pH value (pH 3-4).
But even if everything is right, it’s not enough on its own. If you see potassium sorbate you should see some other preservative next to it too.
BTW, it’s also a food preservative and even has an E number, E202.
A helper ingredient that helps to make the products stay nice longer, aka preservative. It works mainly against fungi.
It’s pH dependent and works best at acidic pH levels (3-5). It’s not strong enough to be used in itself so it’s always combined with something else, often with potassium sorbate.
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
Citric acid comes from citrus fruits and is an AHA. If these magic three letters don’t tell you anything, click here and read our detailed description on glycolic acid, the most famous AHA.
So citric acid is an exfoliant, that can - just like other AHAs - gently lift off the dead skin cells of your skin and make it more smooth and fresh.
There is also some research showing that citric acid with regular use (think three months and 20% concentration) can help sun-damaged skin, increase skin thickness and some nice hydrating things called glycosaminoglycans in the skin.
But according to a comparative study done in 1995, citric acid has less skin improving magic properties than glycolic or lactic acid. Probably that’s why citric acid is usually not used as an exfoliant but more as a helper ingredient in small amounts to adjust the pH of a formulation.
The unfancy name for it is lye. It’s a solid white stuff that’s very alkaline and used in small amounts to adjust the pH of the product and make it just right.
For example, in case of AHA or BHA exfoliants, the right pH is super-duper important, and pH adjusters like sodium hydroxide are needed.
BTW, lye is not something new. It was already used by ancient Egyptians to help oil and fat magically turn into something else. Can you guess what? Yes, it’s soap. It still often shows up in the ingredient list of soaps and other cleansers.
Sodium hydroxide in itself is a potent skin irritant, but once it's reacted (as it is usually in skin care products, like exfoliants) it is totally harmless.
Exactly what it sounds: nice smelling stuff put into cosmetic products so that the end product also smells nice. Fragrance in the US and parfum in the EU is a generic term on the ingredient list that is made up of 30 to 50 chemicals on average (but it can have as much as 200 components!).
If you are someone who likes to know what you put on your face then fragrance is not your best friend - there's no way to know what’s really in it.
Also, if your skin is sensitive, fragrance is again not your best friend. It’s the number one cause of contact allergy to cosmetics. It’s definitely a smart thing to avoid with sensitive skin (and fragrance of any type - natural is just as allergic as synthetic, if not worse!).
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.
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.
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.
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| what‑it‑does | solvent |
| what‑it‑does | emollient | viscosity controlling | emulsifying | surfactant/cleansing |
| irritancy, com. | 1, 2 |
| what‑it‑does | viscosity controlling |
| what‑it‑does | soothing | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | antioxidant |
| irritancy, com. | 0-3, 0-3 |
| what‑it‑does | antioxidant | soothing |
| what‑it‑does | soothing |
| what‑it‑does | soothing |
| what‑it‑does | emollient |
| what‑it‑does | emollient | perfuming |
| irritancy, com. | 0, 4 |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | exfoliant |
| what‑it‑does | antioxidant | skin brightening |
| what‑it‑does | emollient | perfuming |
| irritancy, com. | 0, 3 |
| what‑it‑does | emollient |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | antioxidant |
| what‑it‑does | buffering | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| what‑it‑does | antioxidant |
| what‑it‑does | cell-communicating ingredient |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | emollient | viscosity controlling |
| what‑it‑does | soothing | emollient | moisturizer/humectant |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | moisturizer/humectant | solvent |
| irritancy, com. | 0, 1 |
| what‑it‑does | emollient |
| what‑it‑does | emollient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | emollient |
| what‑it‑does | emollient |
| what‑it‑does | emollient |
| what‑it‑does | emollient |
| irritancy, com. | 0, 1 |
| what‑it‑does | surfactant/cleansing |
| what‑it‑does | surfactant/cleansing |
| what‑it‑does | emulsifying | surfactant/cleansing |
| what‑it‑does | emulsifying | surfactant/cleansing |
| what‑it‑does | sunscreen |
| irritancy, com. | 0, 0 |
| what‑it‑does | sunscreen |
| what‑it‑does | chelating |
| what‑it‑does | buffering |
| what‑it‑does | antioxidant | preservative |
| what‑it‑does | preservative |
| what‑it‑does | preservative |
| what‑it‑does | preservative | antimicrobial/antibacterial |
| what‑it‑does | preservative |
| what‑it‑does | preservative |
| what‑it‑does | preservative |
| what‑it‑does | preservative |
| what‑it‑does | antimicrobial/antibacterial | preservative | surfactant/cleansing |
| what‑it‑does | buffering | preservative |
| what‑it‑does | buffering |
| what‑it‑does | buffering |
| what‑it‑does | perfuming |
| what‑it‑does | perfuming |
| what‑it‑does | perfuming | solvent |
| what‑it‑does | preservative | perfuming | solvent | viscosity controlling |