What's inside
What's inside
Key Ingredients
Benefits
Concerns
Ingredients Side-by-side
Aloe Barbadensis Leaf Juice
Skin ConditioningWater
Skin ConditioningCentella Asiatica Extract
CleansingGlyceryl Stearate
EmollientPEG-100 Stearate
SurfactantCetearyl Alcohol
EmollientIsononyl Isononanoate
EmollientC12-15 Alkyl Benzoate
AntimicrobialSaccharide Isomerate
HumectantDimethicone/Vinyl Dimethicone Crosspolymer
Skin ConditioningGlycerin
HumectantBetaine
HumectantIsopentyldiol
HumectantButylene Glycol
HumectantSqualane
EmollientPanthenol
Skin ConditioningCaffeine
Skin ConditioningCyclopentasiloxane
EmollientCetyl Palmitate
EmollientCeteareth-12
EmulsifyingCeteareth-20
CleansingLecithin
EmollientTheobroma Grandiflorum Seed Butter
Skin ConditioningSodium Acrylates Copolymer
Zea Mays Germ Oil
EmollientPotassium Cetyl Phosphate
EmulsifyingTriticum Vulgare Germ Oil
EmollientChamomilla Recutita Flower Extract
MaskingCaprylic/Capric Triglyceride
MaskingCalendula Officinalis Flower Extract
MaskingMacadamia Ternifolia Seed Oil
EmollientSimmondsia Chinensis Seed Oil
EmollientDimethicone
EmollientPhenoxyethanol
PreservativeAllantoin
Skin ConditioningPolysorbate 20
EmulsifyingPentylene Glycol
Skin ConditioningSodium Polyacrylate
AbsorbentHydrogenated Polydecene
EmollientTrideceth-6
EmulsifyingTocopheryl Acetate
AntioxidantSodium Hyaluronate
HumectantSodium PCA
HumectantErythritol
HumectantCarrageenan
Xanthan Gum
EmulsifyingPropanediol
SolventAcrylates/C10-30 Alkyl Acrylate Crosspolymer
Emulsion StabilisingHelianthus Annuus Seed Oil
EmollientPhytosphingosine
Skin ConditioningCeramide NP
Skin ConditioningHydrogenated Lecithin
EmulsifyingAsiaticoside
AntioxidantMadecassic Acid
Skin ConditioningAsiatic Acid
Skin ConditioningCaprylyl Glycol
EmollientSodium Hyaluronate Crosspolymer
HumectantSodium Acetylated Hyaluronate
HumectantHydrolyzed Sodium Hyaluronate
Skin ConditioningTetrasodium EDTA
Sodium Hydroxide
BufferingTocopherol
AntioxidantPanthenyl Triacetate
Sodium Citrate
BufferingCitric Acid
BufferingSodium Benzoate
MaskingPotassium Sorbate
PreservativeEthylhexylglycerin
Skin ConditioningBenzoic Acid
MaskingAscorbic Acid
AntioxidantAloe Barbadensis Leaf Juice, Water, Centella Asiatica Extract, Glyceryl Stearate, PEG-100 Stearate, Cetearyl Alcohol, Isononyl Isononanoate, C12-15 Alkyl Benzoate, Saccharide Isomerate, Dimethicone/Vinyl Dimethicone Crosspolymer, Glycerin, Betaine, Isopentyldiol, Butylene Glycol, Squalane, Panthenol, Caffeine, Cyclopentasiloxane, Cetyl Palmitate, Ceteareth-12, Ceteareth-20, Lecithin, Theobroma Grandiflorum Seed Butter, Sodium Acrylates Copolymer, Zea Mays Germ Oil, Potassium Cetyl Phosphate, Triticum Vulgare Germ Oil, Chamomilla Recutita Flower Extract, Caprylic/Capric Triglyceride, Calendula Officinalis Flower Extract, Macadamia Ternifolia Seed Oil, Simmondsia Chinensis Seed Oil, Dimethicone, Phenoxyethanol, Allantoin, Polysorbate 20, Pentylene Glycol, Sodium Polyacrylate, Hydrogenated Polydecene, Trideceth-6, Tocopheryl Acetate, Sodium Hyaluronate, Sodium PCA, Erythritol, Carrageenan, Xanthan Gum, Propanediol, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Helianthus Annuus Seed Oil, Phytosphingosine, Ceramide NP, Hydrogenated Lecithin, Asiaticoside, Madecassic Acid, Asiatic Acid, Caprylyl Glycol, Sodium Hyaluronate Crosspolymer, Sodium Acetylated Hyaluronate, Hydrolyzed Sodium Hyaluronate, Tetrasodium EDTA, Sodium Hydroxide, Tocopherol, Panthenyl Triacetate, Sodium Citrate, Citric Acid, Sodium Benzoate, Potassium Sorbate, Ethylhexylglycerin, Benzoic Acid, Ascorbic Acid
Water
Skin ConditioningPropanediol
SolventCentella Asiatica Leaf Water
Skin ConditioningButylene Glycol
HumectantCaprylic/Capric Triglyceride
MaskingPanthenol
Skin ConditioningDiisostearyl Malate
EmollientPolyglyceryl-3 Methylglucose Distearate
EmulsifyingButyrospermum Parkii Butter
Skin ConditioningGlyceryl Stearate
EmollientMacadamia Ternifolia Seed Oil
EmollientCetearyl Alcohol
EmollientHydrogenated Poly(C6-14 Olefin)
EmollientHydrogenated Polydecene
EmollientHydrogenated Polyisobutene
Emollient1,2-Hexanediol
Skin ConditioningPEG-8
HumectantPEG-100 Stearate
SurfactantPolyacrylate-13
Palmitic Acid
EmollientTocopheryl Acetate
AntioxidantBeeswax
Emulsion StabilisingGlycerin
HumectantStearic Acid
CleansingPhenoxyethanol
PreservativePolyisobutene
Asiaticoside
AntioxidantCarbomer
Emulsion StabilisingMadecassic Acid
Skin ConditioningAsiatic Acid
Skin ConditioningSpirulina Platensis Powder
Skin ProtectingAlcohol
AntimicrobialPolysorbate 20
EmulsifyingEthylhexylglycerin
Skin ConditioningLavandula Angustifolia Oil
MaskingSorbitan Isostearate
EmulsifyingAdenosine
Skin ConditioningCeramide AP
Skin ConditioningCitrus Grandis Peel Oil
MaskingHydrogenated Lecithin
EmulsifyingDisodium EDTA
Rosmarinus Officinalis Leaf Oil
MaskingAnthemis Nobilis Flower Oil
MaskingSodium Hyaluronate
HumectantCentella Asiatica Extract
CleansingTheobroma Cacao Extract
Skin ConditioningDextrin
AbsorbentHouttuynia Cordata Extract
Skin ConditioningAniba Rosaeodora Wood Oil
AstringentCentella Asiatica Meristem Cell Culture
AntioxidantMadecassoside
AntioxidantCitric Acid
BufferingAchillea Millefolium Extract
CleansingArtemisia Absinthium Extract
Skin ConditioningArnica Montana Flower Extract
MaskingGentiana Lutea Root Extract
Skin ConditioningSucrose Laurate
EmollientSodium Glycerophosphate
Selaginella Lepidophylla Extract
EmollientPotassium Magnesium Aspartate
BufferingLysolecithin
EmulsifyingMagnesium Gluconate
Skin ConditioningCalcium Gluconate
HumectantPotassium Sorbate
PreservativeSodium Ascorbyl Phosphate
AntioxidantSodium Benzoate
MaskingXanthan Gum
EmulsifyingWater, Propanediol, Centella Asiatica Leaf Water, Butylene Glycol, Caprylic/Capric Triglyceride, Panthenol, Diisostearyl Malate, Polyglyceryl-3 Methylglucose Distearate, Butyrospermum Parkii Butter, Glyceryl Stearate, Macadamia Ternifolia Seed Oil, Cetearyl Alcohol, Hydrogenated Poly(C6-14 Olefin), Hydrogenated Polydecene, Hydrogenated Polyisobutene, 1,2-Hexanediol, PEG-8, PEG-100 Stearate, Polyacrylate-13, Palmitic Acid, Tocopheryl Acetate, Beeswax, Glycerin, Stearic Acid, Phenoxyethanol, Polyisobutene, Asiaticoside, Carbomer, Madecassic Acid, Asiatic Acid, Spirulina Platensis Powder, Alcohol, Polysorbate 20, Ethylhexylglycerin, Lavandula Angustifolia Oil, Sorbitan Isostearate, Adenosine, Ceramide AP, Citrus Grandis Peel Oil, Hydrogenated Lecithin, Disodium EDTA, Rosmarinus Officinalis Leaf Oil, Anthemis Nobilis Flower Oil, Sodium Hyaluronate, Centella Asiatica Extract, Theobroma Cacao Extract, Dextrin, Houttuynia Cordata Extract, Aniba Rosaeodora Wood Oil, Centella Asiatica Meristem Cell Culture, Madecassoside, Citric Acid, Achillea Millefolium Extract, Artemisia Absinthium Extract, Arnica Montana Flower Extract, Gentiana Lutea Root Extract, Sucrose Laurate, Sodium Glycerophosphate, Selaginella Lepidophylla Extract, Potassium Magnesium Aspartate, Lysolecithin, Magnesium Gluconate, Calcium Gluconate, Potassium Sorbate, Sodium Ascorbyl Phosphate, Sodium Benzoate, Xanthan Gum
Reviews
Ingredients Explained
These ingredients are found in both products.
Ingredients higher up in an ingredient list are typically present in a larger amount.
Asiatic Acid is a major component of Centella Asiatica Extract. It has wound-healing, anti-inflammatory, and antioxidant properties.
Studies show Asiatic Acid is able to block the pathway for skin inflammation receptors, helping to soothe skin.
As an antioxidant, asiatic acid helps protect our skin against damaging environmental factors.
Learn more about Asiatic AcidAsiaticoside comes from the super popular skin-soothing ingredient, Centella asiatica. It's the reason centella-based products have a strong reputation for repairing and calming skin, along with its sibling compound Madecassoside.
Research from 2016-2025 supports its role in:
You'll usually find this in concentrations between 0.2-5%.
Learn more about AsiaticosideButylene Glycol (or BG) is used within cosmetic products for a few different reasons:
Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.
Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.
Learn more about Butylene GlycolCaprylic/Capric Triglyceride (aka MCT Oil) is a lightweight emollient, solvent, and texture enhancer. It is considered a skin-softener by helping to prevent moisture loss.
Though it behaves like an oil, it is not technically one due to its chemical composition. One perk of this ingredient is that it is very stable, resistant to oxidation, and unlikely to go rancid.
In practice, that translates to a long shelf life and a consistently elegant skin feel.
While there is an assumption Caprylic Triglyceride can clog pores due to it being derived from coconut oil, there is no research supporting this. Just patch test if you have concerns.
Fractionated coconut oil and MCT Oil are both listed as Caprylic/Capric Triglyceride according to INCI. This is because INCI names are based on the ingredient’s final chemical composition and not its marketing name or source.
This ingredient is treated as the gold standard fungal acne safe oil. Even though it is coconut derived, the problematic lauric acid is stripped out.
This leaves just caprylic (C8) and capric (C10) acid. These chain lengths actually trend antifungal; a 2020 study found caprylic acid was enough to disrupt Malassezia furfur cell membrane, with a caprylic acid derivative damaging membrane structures at concentrations as low as 0.2%.
Learn more about Caprylic/Capric TriglycerideCentella Asiatica Extract (Centella) is derived from an herb native to Southeast Asia. It is famous for its anti-inflammatory and soothing properties.
Centella is rich in antioxidants and amino acids, such as Madecassic Acid and Asiaticoside.
Studies show the compounds in centella help with:
The combination of all these properties makes centella effective at soothing, hydrating, and protecting the skin.
Other great components of centella include Vitamin A, vitamin C, several B vitamins, and Asiatic Acid.
Fun fact: Centella has been used as a medicine and in food for many centuries. As a medicine, it is used to treat burns, scratches, and wounds.
Learn more about Centella Asiatica ExtractCetearyl alcohol is a waxy mixture of two fatty alcohols: cetyl alcohol and stearyl alcohol. It is an emollient and emulsifier.
Despite having "alcohol" in its name, it has nothing to do with drying solvent alcohols; the FDA also allows "alcohol-free" products to contain fatty alcohols like this ingredient.
It plays several roles in a formula:
Typical use levels for this ingredient sit around 1-10% and the Cosmetic Ingredient Review Expert Panel has affirmed safety at concentrations up to 25% in leave-on products.
Multiple assessments have found it to be non-irritating and non-sensitizing to most people.
However, there have been some cases of allergic contact dermatitis in patients with chronically compromised skin barriers.
Cetearyl alcohol has a comedogenic rating of 2 and irritancy rating of 1. Both of these numbers come from the 1989 study that used rabbit ears; a "2" means mildly comedogenic and a "1" means low irritancy.
Here's the catch: rabbit skin is more sensitive than human skin and throws a lot of false positives. A 1996 reappraisal found that ingredients rated 1-2 in the rabbit ear tests are generally safe for humans.
Remember comedogenic ratings are unable to assess the entire formula of a product or how it will react on your skin. Just be sure to patch test if you are unsure about certain ingredients.
This ingredient is not fungal acne safe. Cetearyl alcohol is a fatty alcohol with chain lengths that fall within the range that Malassezia can metabolize.
A 2019 study has also observed Malassezia growth in the presence of this ingredient, confirming it to be not-fungal acne safe.
Learn more about Cetearyl AlcoholCitric Acid is an alpha hydroxy acid (AHA) naturally found in citrus fruits like oranges, lemons, and limes.
Like other AHAs, citric acid can exfoliate skin by breaking down the bonds that hold dead skin cells together. This helps reveal smoother and brighter skin underneath.
However, this exfoliating effect only happens at high concentrations (20%) which can be hard to find in cosmetic products.
Due to this, citric acid is usually included in small amounts as a pH adjuster. This helps keep products slightly more acidic and compatible with skin's natural pH.
In skincare formulas, citric acid can:
While it can provide some skin benefits, research shows lactic acid and glycolic acid are generally more effective and less irritating exfoliants.
Most citric acid used in skincare today is made by fermenting sugars (usually from molasses). This synthetic version is identical to the natural citrus form but easier to stabilize and use in formulations.
Read more about some other popular AHA's here:
Learn more about Citric AcidEthylhexylglycerin is created from glycerin. It is a multitasker ingredient that:
The CIR Expert Panel found minimal skin absorption or sensitization of any kind in a safety assessment. Though this ingredient is considered well-tolerated, a small number of cases of allergic dermatitis have been published since 2002. Just be sure to patch test if you are unsure.
Industry-reported use ranges from 8% in rinse-off products and 2% in leave-on formulations.
Learn more about EthylhexylglycerinGlycerin (or glycerol) is a compound naturally found in your skin. It's a powerhouse humectant that pulls water into the stratum corneum.
Topically, glycerin does several things at once:
Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.
Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.
This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.
Just know very high concentrations (>40%) can feel tacky in low humidity.
Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.
Learn more about GlycerinGlyceryl Stearate is made by reacting glycerin with stearic acid (typically sourced from plant oils like palm or coconut). It's an emulsifier, emollient, and mild occlusive.
Emulsifiers help ingredients like oil and water stay mixed so your formula stays nicely blended and uniform in texture.
This ingredient is typically used in concentrations between 1-10%. Studies have found it to be non-sensitizing, non-phototoxic, and non-photoallergenic.
A close cousin of this ingredient is Glyceryl Stearate SE ("self-emulsifying"). This just has a small amount of sodium or potassium stearate added so it can emulsify without a co-emulsifier.
Since this ingredient is an ester of a C18 fatty acid, it may not be fungal acne safe. The Malassezia yeast can potentially metabolize within the C11-C24 range.
Fun fact: The human body also creates Glyceryl Stearate naturally.
Learn more about Glyceryl StearateHydrogenated Lecithin is a more stable version of lecithin.
It's made by taking lecithin (a phospholipid commonly found in soybeans and egg yolks) and hydrogenating it. This just means the unsaturated fatty acids are turned into saturated ones so they don't go bad as easily.
This ingredient is an emollient, emulsifier, and penetration enhancer. As an emollient, it helps soften and hydrate skin by trapping moisture within. As an emulsifier, it prevents oil and water ingredients from separating.
Hydrogenated Lecithin can form tiny spherical structures made of phospholipid bilayers called liposomes. These liposomes are able to capture compounds inside their structure and deliver them through the skin barrier.
Because phospholipids are a natural component of our cell membranes, this ingredient is inherently compatible with skin.
A 2021 study found lecithin-based surfactants were less harsh and more tolerable comared to Sodium Lauryl Sulfate (SLS).
Learn more about Hydrogenated LecithinHydrogenated Polydecene is a synthetic emollient. It forms a non-occlusive film on the skin's surface to provide a silky feel without being greasy.
In vivo studies in volunteers with atopic and dry skin showed no irritation or intolerance. The volunteers also saw a positive effect in dryness, scaling, and roughness after 28 days of use.
Concentrations up to 100% in guinea pig tests found it to be non-sensitizing and completely safe for use in cosmetics.
Learn more about Hydrogenated PolydeceneThis ingredient is also known as Macadamia Seed Oil. It's an emollient with a fatty acid profile that closely mirrors the skin's own lipid makeup.
The palmitoleic acid content is especially notable as it's somewhat rare in plant oils. Palmitoleic acid is something your skin already makes naturally. It helps keep cell membranes structured and plays a role in fighting off harmful microbes.
This palmitoleic content is also part of why macademia seed oil absorbs quickly and doesn't leave much of a greasy residue.
It also contains oleic acid, linoleic acid, and phytosterols that can help reduce redness.
In vitro research has shown the oil to have meaningful antioxidant activity, protect fats in the skin from oxidative damage, and slow down the enzyme that breaks down hyaluronic acid.
A 2024 clinical study found it effective at improving skin hydratino and reducing wrinkle appearance when formulated into nanoemulsions.
Because it carries oleic acid (C18) and palmitic acid (C16), this ingredient may not be fungal acne safe. This is because the Malassezia yeast metabolizes in the C11-24 chain length range.
You'll also see this ingredient listed as: Macadamia Integrifolia Seed Oil .
These two oils are identical in composition and M. ternifolia is an older INCI naming convention for the edible macadamia nut while M. integrifolia is the species actually cultivated for oil production. Both names refer to the same oil.
Learn more about Macadamia Ternifolia Seed OilMadecassic Acid is a major component of Centella Asiatica Extract. It has anti-inflammatory and antioxidant properties.
It is a triterpenoid, meaning it naturally acts as an antioxidant. Antioxidants protect your skin against damage from environmental factors such as pollution and UV.
Studies show Madecassic Acid helps soothe the skin due to its ability to block inflammation pathways.
Learn more about Madecassic AcidPanthenol is a common ingredient that helps hydrate and soothe the skin. It is found naturally in our skin and hair.
There are two forms of panthenol: D and L.
D-panthenol is also known as dexpanthenol. Most cosmetics use dexpanthenol or a mixture of D and L-panthenol.
Panthenol is famous due to its ability to go deeper into the skin's layers. Using this ingredient has numerous pros (and no cons):
Like hyaluronic acid, panthenol is a humectant. Humectants are able to bind and hold large amounts of water to keep skin hydrated.
This ingredient works well for wound healing. It works by increasing tissue in the wound and helps close open wounds.
Once oxidized, panthenol converts to pantothenic acid. Panthothenic acid is found in all living cells.
This ingredient is also referred to as pro-vitamin B5.
Learn more about PanthenolPeg-100 Stearate is an emollient and emulsifier. As an emollient, it helps keep skin soft by trapping moisture in. On the other hand, emulsifiers help prevent oil and water from separating in a product.
PEGS are a hydrophilic polyether compound . There are 100 ethylene oxide monomers in Peg-100 Stearate. Peg-100 Stearate is polyethylene glycol ester of stearic acid.
Phenoxyethanol is a preservative that has germicide, antimicrobial, and aromatic properties. Studies show that phenoxyethanol can prevent microbial growth. By itself, it has a scent that is similar to that of a rose.
It's often used in formulations along with Caprylyl Glycol to preserve the shelf life of products.
Polysorbate 20 is a gentle, water-soluble emulsifier and mild surfactant. It stops oil and water from separating to keep your formulas blended and stable.
It also acts as a mild penetration enhancer by helping active ingredients absorb slightly better.
The common safety discussion around this ingredient involves a manufacturing byproduct called 1,4-dioxane.
Trace amounts can form during production but the EU's Scientific Committee on Consumer Safety has concluded that levels at/below 10 ppm in finished products are safe (commercial products consistently fall within acceptable margins).
True allergic reactions are uncommon and the CIR Expert Panel has confirmed this ingredient to be safe as used in cosmetics.
Because it is derived from lauric acid, it may not be fungal acne safe.
Learn more about Polysorbate 20Potassium Sorbate is a preservative used to prevent yeast and mold in products. It is commonly found in both cosmetic and food products.
This ingredient comes from potassium salt derived from sorbic acid. Sorbic acid is a natural antibiotic and effective against fungus.
Both potassium sorbate and sorbic acid can be found in baked goods, cheeses, dried meats, dried fruit, ice cream, pickles, wine, yogurt, and more.
You'll often find this ingredient used with other preservatives.
Learn more about Potassium SorbatePropanediol is an all-star ingredient. It softens, hydrates, and smooths the skin.
It’s often used to:
Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.
Learn more about PropanediolSodium Benzoate is a preservative. It's used in both cosmetic and food products to inhibit the growth of mold and bacteria. It is typically produced synthetically.
Both the US FDA and EU Health Committee have approved the use of sodium benzoate. In the US, levels of 0.1% (of the total product) are allowed.
Sodium benzoate works as a preservative by inhibiting the growth of bacteria inside of cells. It prevents the cell from fermenting a type of sugar using an enzyme called phosphofructokinase.
It is the salt of benzoic acid. Foods containing sodium benzoate include soda, salad dressings, condiments, fruit juices, wines, and snack foods.
Studies for using ascorbic acid and sodium benzoate in cosmetics are lacking, especially in skincare routines with multiple steps.
We always recommend speaking with a professional, such as a dermatologist, if you have any concerns.
Learn more about Sodium BenzoateSodium Hyaluronate is the salt form of hyaluronic acid. It is a long sugar chain that is naturally found in your skin, joints, and connective tissue that maintains hydration and elasticity.
In skincare, it works as a humectant. It pulls water from the environment and deeper layers of skin and binds it to the surface.
Interestingly, the size of the molecule affects its behavior:
Some clinical evidence links low molecular weight versions to improved wrinkle depth, elasticity, anti-inflammatory effects, and barrier repair.
Many serums use a blend of both weights so you can get surface hydration plus longer-lasting and deeper effects.
You'll typically see concentrations between 0.1-2% for this ingredient.
Learn more about Sodium HyaluronateTocopheryl Acetate is AKA Vitamin E. It is an antioxidant and protects your skin from free radicals. Free radicals damage the skin by breaking down collagen.
One study found using Tocopheryl Acetate with Vitamin C decreased the number of sunburned cells.
Tocopheryl Acetate is commonly found in both skincare and dietary supplements.
Learn more about Tocopheryl AcetateWater. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.
So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.
You'll also recognize water as that liquid we all need to stay alive. If you see this, drink a glass of water. Remember to stay hydrated!
Learn more about WaterXanthan gum is used as a stabilizer and thickener within cosmetic products. It helps give products a sticky, thick feeling - preventing them from being too runny.
On the technical side of things, xanthan gum is a polysaccharide - a combination consisting of multiple sugar molecules bonded together.
Xanthan gum is a pretty common and great ingredient. It is a natural, non-toxic, non-irritating ingredient that is also commonly used in food products.
Learn more about Xanthan Gum