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Colleen Rothschild Age Renewal Super Serum

Age Renewal Super Serum

Age Renewal Super Serum effectively fights the six signs of aging: texture, dehydration, elasticity, fine lines, radiance, and tone. This concentrated formula is infused with more than 20 potent ingredients, including peptides, collagen boosters, amino acids, vitamins, and plant extracts. Combined, this serum helps to restore the skin’s complexion to its most youthful radiance and texture.
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Highlights

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Skim through

Ingredient name what-it-does irr., com. ID-Rating
Aqua (Water) solvent
Acetyl Octapeptide-3 cell-communicating ingredient, moisturizer/​humectant goodie
Glycerin skin-identical ingredient, moisturizer/​humectant 0, 0 superstar
C12-15 Alkyl Benzoate emollient, antimicrobial/​antibacterial
(Caprylic/-Capric Triglyceride emollient
Rhus Verniciflua Peel Cera emollient
Silybum Marianum Ethyl Ester
Moringa Oil/Hydrogenated Moringa Oil Esters (Moringa Butter)
Phenoxyethanol preservative
Cetearyl Alcohol emollient, viscosity controlling, emulsifying, surfactant/​cleansing 1, 2
Cetyl Alcohol emollient, emulsifying, viscosity controlling, surfactant/​cleansing 2, 2
Palmitoyl Tripeptide-5 cell-communicating ingredient goodie
Sodium Hyaluronate (Hyaluronic Acid) skin-identical ingredient, moisturizer/​humectant 0, 0 goodie
Beta Vulgaris Root Extract antioxidant, moisturizer/​humectant goodie
Hydrolyzed Corn Starch moisturizer/​humectant, viscosity controlling
Algae Extract (Gwennis Extract) emollient, moisturizer/​humectant goodie
Paeonia Albiflora Root Extract (Velvet Peony Extract)
Hippophae Rhamnoides Oil (Sea Buckthorn Oil) antioxidant, emollient goodie
Vaccinium Macrocarpon Seed Oil (Cranberry Seed Oil) emollient goodie
Rice Ferment Filtrate (Japanese Rice Protein)
Copper Gluconate soothing goodie
Lactic Acid exfoliant, moisturizer/​humectant, buffering superstar
Tocopherol (Vitamin E) antioxidant 0-3, 0-3 goodie
Aloe Barbadensis Leaf Juice soothing, moisturizer/​humectant goodie
Hydrogenated Lecithin emollient, emulsifying goodie
PEG-8/Smdi Copolymer
Glycine Soja Extract
Squalane skin-identical ingredient, emollient 0, 1 goodie
Dimethicone emollient 0, 1
Stearic Acid emollient, viscosity controlling 0, 2-3
Polysorbate 80 emulsifying, surfactant/​cleansing 0, 0
Isohexadecane emollient, solvent
Sodium Acrylate/Sodium Acryloyldimethyl Taurate/Acrylamide Copolymer viscosity controlling
Glyceryl Stearate emollient, emulsifying 0, 1-2
PEG-100 Stearate surfactant/​cleansing, emulsifying 0, 0
Phenyl Trimethicone emollient
Polysorbate 60 emulsifying, surfactant/​cleansing
Disodium EDTA chelating, viscosity controlling
Ethylhexylglycerin preservative
Xanthan Gum viscosity controlling
Sodium Hydroxide buffering
Benzyl Benzoate solvent, perfuming, antimicrobial/​antibacterial icky
Parfum perfuming icky
Linalool perfuming icky
Limonene perfuming, solvent icky

Colleen Rothschild Age Renewal Super Serum
Ingredients explained

Also-called: 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. 

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. 

Also-called: SNAP-8, Acetyl Glutamyl Heptapeptide-1 | What-it-does: cell-communicating ingredient, moisturizer/humectant

A newer and, molecule-wise, somewhat bigger version of the famous "Botox-like" peptide called Acetyl Hexapeptide-8 or Argireline. Just like Argireline, Acetyl Octapeptide-3 is also claimed to influence the muscle contraction process that results in a more relaxed and line-free face, especially around the forehead and the eyes.  

While Argireline counts as a pretty well-proven peptide, with multiple studies confirming its anti-wrinkle efficacy, we cannot say the same for Acetyl Octapeptide-3. What we have is the manufacturer's claim that comparing 10% Argireline with 10% SNAP-8 solution (that means 0.005% pure peptide powder) the SNAP-8 peptide did a bit better as it reduced wrinkles by 34.98% vs 27.05% reduction for Argireline (twice a day use for 28 days on 17 women). 

Other than that, we can write here pretty much the same as at Argireline. Obviously, no peptide works as effectively as real Botox, and the Botox-inspired peptides are quick fixes rather than being collagen builders or real preventers of structural aging. They are nice additions to an anti-aging skincare routine but not the real superstars (think vitamin CAHAs or retinol).

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 at higher concentrations up to 20-40% (around 10% is a good usability-effectiveness sweet spot)
  • High-glycerin moisturizers are awesome for treating severely dry skin
Read all the geeky details about Glycerin here >>

An often used emollient with a light and silky feel. It's very mild to both skin and eyes and spreads nicely and easily. It's often used in sunscreens as it's also an excellent solvent for sunscreen agents. 

What-it-does: emollient

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. 

What-it-does: emollient

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: preservative

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.

What-it-does: emollient, viscosity controlling, emulsifying, emulsion stabilising, surfactant/cleansing | Irritancy: 1 | Comedogenicity: 2

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.

What-it-does: emollient, emulsifying, viscosity controlling, surfactant/cleansing, 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.

Also-called: Syn-Coll | What-it-does: cell-communicating ingredient

A tripeptide (three amino acids attached to each other: Lys-Val-Lys) that's claimed to protect and boost collagen and improve skin texture.

The manufacturer did an in-vivo (made on real people) study with 45 volunteers and found that used twice daily for 84 days 1% and 2.5% Syn-Coll reduces the appearance of wrinkles by 7 and 12% respectively. In another study (also by the manufacturer) with 33 female Chinese volunteers, 77% of the participants felt that Syn-Coll visibly improved the firmness and elasticity of the skin after 4 weeks. What's more, 60% of the participants also noticed a reduction in the look of the pore size also after 4 weeks of treatment. 

What-it-does: skin-identical ingredient, moisturizer/humectant | Irritancy: 0 | Comedogenicity: 0

It’s the - sodium form - cousin of the famous NMFhyaluronic acid (HA). If HA does not tell you anything we have a super detailed, geeky explanation about it here.  The TL; DR version of HA is that it's a huge polymer (big molecule from repeated subunits) found in the skin that acts as a sponge helping the skin to hold onto water, being plump and elastic. HA is famous for its crazy water holding capacity as it can bind up to 1000 times its own weight in water.

As far as skincare goes, sodium hyaluronate and hyaluronic acid are pretty much the same and the two names are used interchangeably. As cosmetic chemist kindofstephen writes on reddit  "sodium hyaluronate disassociates into hyaluronic acid molecule and a sodium atom in solution". 

In spite of this, if you search for "hyaluronic acid vs sodium hyaluronate" you will find on multiple places that sodium hyaluronate is smaller and can penetrate the skin better. Chemically, this is definitely not true, as the two forms are almost the same, both are polymers and the subunits can be repeated in both forms as much as you like. (We also checked Prospector for sodium hyaluronate versions actually used in cosmetic products and found that the most common molecular weight was 1.5-1.8 million Da that absolutely counts as high molecular weight).

What seems to be a true difference, though, is that the salt form is more stable, easier to formulate and cheaper so it pops up more often on the ingredient lists. 

If you wanna become a real HA-and-the-skin expert you can read way more about the topic at hyaluronic acid (including penetration-questions, differences between high and low molecular weight versions and a bunch of references to scientific literature).

Also-called: Beet Root Extract | What-it-does: antioxidant, moisturizer/humectant

Beetroot is a beautifully colored vegetable that you probably know from the kitchen. As for skincare - according to manufacturer info - it works as a natural moisturizer that might be able to increase the concentration of NMFs (natural moisturizing factors) in the upper layer of the skin giving skin both immediate and longer term hydration. 

According to Paula's Choice, it's also a colorant and a source of antioxidants

It's the chemically chopped up version of corn starch. According to manufacturer info it helps to keep formulas together (binding), and improves foam quality (makes nice, creamy foam :)). It's also a blend of poly- and monosaccharides and works as a skin moisturizer giving products a nice soft feel.

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.

Also-called: Sea Buckthorn Berry Oil;Hippophae Rhamnoides Fruit Oil | What-it-does: antioxidant, emollient

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. 

Also-called: Cranberry Seed Oil | What-it-does: emollient

yellow-greenish oil coming from the seeds of Cranberry. Similar to other emollient plant oils, it is loaded with nice fatty acids. It contains a very balanced 1:1 ratio of anti-inflammatory omega-3 (aka linolenic acid) and barrier repairing omega-6 (aka linoleic acid) (30-38%), and also a decent amount of skin-nourishing omega-9, aka oleic acid. It also has high vitamin E content and significant antioxidant properties. 

Other than being a nice emollient plant oil, we also found a research showing that cranberry oil has wound-healing potential

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

The gluconate part is there to promote the bioavailability of copper and it also plays a role in cellular regeneration (involved in the synthesis of ribose sugars, structural components of DNA and RNA).

Lactic Acid - superstar
  • It’s the second most researched AHA after glycolic acid
  • It gently lifts off dead skin cells to reveal newer, fresher, smoother skin
  • It also has amazing skin hydrating properties
  • In higher concentration (10% and up) it improves skin firmness, thickness and wrinkles
  • Choose a product where you know the concentration and pH value because these two greatly influence effectiveness
  • Don’t forget to use your sunscreen (in any case but especially so next to an AHA product)
Read all the geeky details about Lactic Acid here >>

Also-called: Vitamin E | What-it-does: antioxidant | Irritancy: 0-3 | Comedogenicity: 0-3
  • 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
Read all the geeky details about Tocopherol here >>

Also-called: Aloe Vera | What-it-does: soothing, moisturizer/humectant

Aloe Vera is one of today’s magic plants. It does have some very nice properties indeed, though famous dermatologist Leslie Baumann warns us in her book that most of the evidence is anecdotal and the plant might be a bit overhyped.

What research does confirm about Aloe is that it’s a great moisturizer and has several anti-inflammatory (among others contains salicylates, polysaccharides, magnesium lactate and C-glucosyl chromone) as well as some antibacterial components. It also helps wound healing and skin regeneration in general. All in all definitely a goodie. 

What-it-does: emollient, emulsifying

It's the chemically chopped up version of normal lecithin. Most often it's used to create liposomes and to coat and stabilize other ingredients. 

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

Squalane - goodie
What-it-does: skin-identical ingredient, emollient | Irritancy: 0 | Comedogenicity: 1

It seems to us that squalane is in fashion and there is a reason for it. Chemically speaking, it is a saturated  (no double bonds) hydrocarbon (a molecule consisting only of carbon and hydrogen), meaning that it's a nice and stable oily liquid with a long shelf life. 

It occurs naturally in certain fish and plant oils (e.g. olive), and in the sebum (the oily stuff our skin produces) of the human skin. As f.c. puts it in his awesome blog post, squalane's main things are "emolliency, surface occlusion, and TEWL prevention all with extreme cosmetic elegance". In other words, it's a superb moisturizer that makes your skin nice and smooth, without being heavy or greasy.

Another advantage of squalane is that it is pretty much compatible with all skin types and skin conditions. It is excellent for acne-prone skin and safe to use even if you have fungi-related skin issues, like seborrhea or fungal acne.

The unsaturated (with double bonds) and hence less stable version of Squalane is Squalene, you can read about it here >> 

What-it-does: emollient | Irritancy: 0 | Comedogenicity: 1

Probably the most common silicone of all. It is a polymer (created from repeating subunits) molecule and has different molecular weight and thus different viscosity versions from water-light to thick liquid.

As for skincare, it makes the skin silky smooth, creates a subtle gloss and forms a protective barrier (aka occlusive). Also, works well to fill in fine lines and wrinkles and give skin a plump look (of course that is only temporary, but still, it's nice). There are also scar treatment gels out there using dimethicone as their base ingredient. It helps to soften scars and increase their elasticity. 

As for hair care, it is a non-volatile silicone meaning that it stays on the hair rather than evaporates from it and smoothes the hair like no other thing. Depending on your hair type, it can be a bit difficult to wash out and might cause some build-up (btw, this is not true to all silicones, only the non-volatile types). 

What-it-does: emollient, viscosity controlling | Irritancy: 0 | Comedogenicity: 2-3

A common multi-tasker fatty acid. It makes your skin feel nice and smooth (emollient), gives body to cream type products and helps to stabilize water and oil mixes (aka emulsions).

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

A common little helper ingredient that helps water and oil to mix together, aka emulsifier. 

The number at the end refers to the oil-loving part and the bigger the number  the more emulsifying power it has. 20 is a weak emulsifier, rather called solubilizer used commonly in toners while 60 and 80 are more common in serums and creams.

What-it-does: emollient, solvent

A light, velvety, unique skin feel liquid that is a good solvent and also makes the skin feel nice and smooth (aka emollient). It's often used in makeup products mixed with silicones to give shine and slip to the product. It's also great for cleansing dirt and oil from the skin as well as for taking off make-up.

What-it-does: emollient, emulsifying | Irritancy: 0 | Comedogenicity: 1-2

A super common, waxy, white, solid stuff that helps water and oil to mix together, gives body to creams and leaves the skin feeling soft and smooth.

Chemically speaking, it is the attachment of a glycerin molecule to the fatty acid called stearic acid. It can be produced from most vegetable oils (in oils three fatty acid molecules are attached to glycerin instead of just one like here) in a pretty simple, "green" process that is similar to soap making. It's readily biodegradable.

It also occurs naturally in our body and is used as a food additive. As cosmetic chemist Colins writes it, "its safety really is beyond any doubt".

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

A very common water-loving surfactant and emulsifier that helps to keep water and oil mixed nicely together. 

It's often paired with glyceryl stearate - the two together form a super effective emulsifier duo that's salt and acid tolerant and works over a wide pH range. It also gives a "pleasing product aesthetics", so no wonder it's popular.

What-it-does: emollient

A silicone fluid that gives a nonoily, easy to spread emolliency to the formulas. It is also used as a water repellent additive and to reduce the tackiness and stickiness of other ingredients. It also imparts gloss, softness and better manageability to hair.

A common little helper ingredient that helps water and oil to mix together, aka emulsifier.

Super common little helper ingredient that helps products to remain nice and stable for a longer time. It does so by neutralizing the metal ions in the formula (that usually get into there from water) that would otherwise cause some not so nice changes.

It is typically used in tiny amounts, around 0.1% or less.

What-it-does: preservative, deodorant

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

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). 

Also-called: lye | What-it-does: buffering

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.

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.

Parfum - icky
Also-called: Fragrance, Parfum;Parfum/Fragrance | What-it-does: perfuming

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 - 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.

A study made in the UK with 483 people tested the allergic reaction to 3% oxidised linalool and 2.3% had positive test results. 

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

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.  

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 cell-communicating ingredient | moisturizer/humectant
A newer and molecule-wise somewhat bigger version of famous "Botox-like" peptide, Argireline. It is also claimed to influence the muscle contraction process that results in a more relaxed and line-free face. [more]
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 emollient | antimicrobial/antibacterial
An often used emollient with a light and silky feel. It's very mild to both skin and eyes and spreads nicely and easily. It's often used in sunscreens as it's also an excellent solvent for sunscreen agents. 
what‑it‑does emollient
A very common emollient that makes your skin feel nice and smooth. Comes from coconut oil and glycerin, it’s light-textured, clear, odorless and non-greasy. [more]
what‑it‑does emollient
what‑it‑does preservative
Pretty much the current IT-preservative. It’s safe and gentle, and can be used up to 1% worldwide. [more]
what‑it‑does emollient | viscosity controlling | emulsifying | surfactant/cleansing
irritancy, com. 1, 2
A super common multitasker ingredient that gives your skin a nice soft feel (emollient) and gives body to creams. [more]
what‑it‑does emollient | emulsifying | viscosity controlling | surfactant/cleansing
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 cell-communicating ingredient
Syn-Coll - An anti-aging tripeptide that's claimed to protect and boost collagen and improve skin texture. [more]
what‑it‑does skin-identical ingredient | moisturizer/humectant
irritancy, com. 0, 0
It's the salt form of famous humectant and natural moisturizing factor, hyaluronic acid. It can bind huge amounts of water and it's pretty much the current IT-moisturizer. [more]
what‑it‑does antioxidant | moisturizer/humectant
Beetroot is a natural moisturizer, colorant, and antioxidant. [more]
what‑it‑does moisturizer/humectant | viscosity controlling
Chemically chopped up version of corn starch - helps to keep formulas together (binding), and improves foam quality. It's also a skin moisturizer. [more]
what‑it‑does emollient | moisturizer/humectant
An extract that comes from one or more of the 20 000 kinds of algae out there. In general algae extracts serve as moisturizing, emollient and thickening agents, and many of them also have additional anti-aging properties. [more]
what‑it‑does antioxidant | emollient
Sea buckthorn berry oil - contains rare omega-7 fatty acid, antioxidants, and skin-soothing plant sterols. A nice moisturising and skin protecting oil. [more]
what‑it‑does emollient
A yellow-greenish oil coming from the seeds of Cranberry. Similar to other emollient plant oils, it is loaded with nice fatty acids. It contains a very balanced 1:1 ratio of anti-inflammatory omega-3 (aka linolenic acid) and barrier repairing omega-6 (aka linoleic acid) (30-38%), and also a decent amount of skin-nourishing omega-9, aka oleic acid. [more]
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 exfoliant | moisturizer/humectant | buffering
A superstar AHA that not only exfoliates skin but is also a very good moisturizer. In higher concentration (10% and up) it can even improve skin firmness, thickness, and wrinkles. [more]
what‑it‑does antioxidant
irritancy, com. 0-3, 0-3
Pure Vitamin E. Great antioxidant that gives significant photoprotection against UVB rays. Works in synergy with Vitamin C. [more]
what‑it‑does soothing | moisturizer/humectant
The famous aloe vera. A great moisturizer and anti-inflammatory ingredient that also helps wound healing and skin regeneration. [more]
what‑it‑does emollient | emulsifying
It's the chemically chopped up version of normal lecithin. Most often it's used to create liposomes and to coat and stabilize some other ingredient. 
what‑it‑does skin-identical ingredient | emollient
irritancy, com. 0, 1
An emollient and natural moisturizer that can be found also in the sebum (oily stuff our skin produces). It leaves a nice non-greasy, non-heavy feeling on the skin. [more]
what‑it‑does emollient
irritancy, com. 0, 1
A very common silicone that gives both skin and hair a silky smooth feel. It also forms a protective barrier on the skin and fills in fine lines. Also used for scar treatment. [more]
what‑it‑does emollient | viscosity controlling
irritancy, com. 0, 2-3
A common multi-tasker fatty acid that works as an emollient, thickener and emulsion stabilizer. [more]
what‑it‑does emulsifying | surfactant/cleansing
irritancy, com. 0, 0
A common little helper ingredient that helps water and oil to mix together, aka emulsifier. [more]
what‑it‑does emollient | solvent
A light, velvety, unique skin feel liquid that is a good solvent and also makes the skin feel nice and smooth. [more]
what‑it‑does viscosity controlling
what‑it‑does emollient | emulsifying
irritancy, com. 0, 1-2
Waxy, white, solid stuff that helps water and oil to mix together and leaves the skin feeling soft and smooth. [more]
what‑it‑does surfactant/cleansing | emulsifying
irritancy, com. 0, 0
A commonly used water-soluble surfactant and emulsifier. [more]
what‑it‑does emollient
A silicone fluid that gives a nonoily, easy to spread emolliency to the formulas. [more]
what‑it‑does emulsifying | surfactant/cleansing
A common little helper ingredient that helps water and oil to mix together, aka emulsifier.
what‑it‑does chelating | viscosity controlling
Super common little helper ingredient that helps products to remain nice and stable for a longer time. It does so by neutralizing the metal ions in the formula (that usually get into there from water) that would otherwise cause some not so nice changes. [more]
what‑it‑does preservative
It can boost the effectiveness of phenoxyethanol (and other preservatives) and as an added bonus it feels nice on the skin too. [more]
what‑it‑does viscosity controlling
A super commonly used thickener and emulsion stabilizer. [more]
what‑it‑does buffering
Lye - A solid white stuff that’s very alkaline and used in small amount to adjust the pH of the product.  [more]
what‑it‑does solvent | perfuming | antimicrobial/antibacterial
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. One of the “EU 26 fragrances” that has to be labelled separately because of allergen potential.
what‑it‑does perfuming
The generic term for nice smelling stuff put into cosmetic products so that the end product also smells nice. It is made up of 30 to 50 chemicals on average. [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 | 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]