Ingredients 101

As someone with allergies I was taught at an early age to read the ingredients on everything. One of the main things I had to avoid growing up was milk, and my mother taught me two very important things that have stayed with me all of my life:

  1. The order of an ingredient list matters
  2. Common ingredients are sometimes labelled with uncommon names (i.e derivatives)

Armed with just these two facts helped me avoid allergens as a child. I learned that I could eat things like bread because the milk was usually 5 ingredients down the list or further. I also learned that I couldn’t just look for the word ‘milk’. I had to look out for terms like ‘whey’, ‘casien’, and ‘lactose’ which all set off my allergy.

Fast forward to me being an adult, and I’m still reading the ingredients on everything. Because I have sensitive skin. I’m used to it, but it can be very confusing for those who aren’t. Just identifying what an ingredient is supposed to do can add to that confusion. What’s an emulsifier vs an emollient? There’s a difference between moisturizing and hydrating!? (Yes there is). And what the hell is a surface active agent?

The purpose of this post is to answer these questions and shed some light on what ingredients do, how they work, and how to identify them on the label.

Before we get into that though, let’s talk about ingredient labels. According to the FDA, companies are required to list ingredients in order of predominance. Meaning the more of an ingredient the product contains, the higher it will be on the list. Exceptions to this are color additives of any concentration and ingredients that make up 1% or less of a product. These can be listed in any order after the rest of the ingredients are listed by predominance.

So if the vitamin C serum you’re looking at has vitamin C listed in the last 3 ingredients of a paragraph long list, it probably isn’t very concentrated.

Now, onto the fun part. Bear in mind that this isn’t an exhaustive list, and that some ingredients may show up in multiple categories.


The term ‘active’ has a double meaning in the world of skincare. The first definition has to do with FDA regulations and the issue a product claims to address. For example, a product marketed to fight acne may list salicylic acid (SA) as it’s active ingredient. A different product marketed to fade dark spots may list niacinamide as the active ingredient. However, an acne product that contains both will only list SA as the active ingredient. Because the product is marketed to fight acne and not dark spots, niacinamide does not fit the definition of ‘active’ for that product.

The second meaning ‘active’ takes on is a colloquial term referring to things that increase cell turnover. These are things that may cause a purging process for a few weeks because of how they work. Read more about what purging is here.

For simplicity we’ll be using the second definition of ‘active’ for this post, because the FDA definition is only on a case by case basis. Actives will be marked with a double asterisk(**).


Alpha Hydroxy Acids. These refer to a class of chemical exfoliants that work by gently breaking apart the upper layer of skin so that new skin underneath surfaces faster. These can help smooth fine lines and have a brightening effect on the complexion.

  • Glycolic acid
  • Lactic acid (sodium lactate)
  • Malic acid
  • Mandelic acid
  • Tartaric acid
  • Citric acid


Beta Hydroxy Acids. The most common “BHA” in skincare is salicylic acid (SA), although it isn’t by definition a BHA. But it behaves like one, so people refer to it that way. Citric acid is both an AHA and a BHA.

SA is derived from the willow(salix) tree, and works differently than AHAs because it can penetrate oils in the skin, leading to deeper exfoliation. Since a lot of acne is caused by clogged pores, this is also why it works so well as an acne medication.

Keep in mind however that willow bark water/extract is not the same as SA. Willow bark contains salicin, which is an anti-inflammatory and precursor to SA as well as aspirin, but doesn’t possess SA’s exfoliating properties.


Strap in, we’re gonna be on this section a while. This was one of the most confusing things I came across when I started my skincare journey. Some sources say that a surfactant is a type of emulsifier, while others will claim the reverse. From what I understand, a surfactant helps to merge imiscible substances by acting on the surface tension between them (hence why they’re ‘surface active agents’). Emulsifiers do the exact same thing. So an emulsifier is a type of surfactant.

But, when we think of surfactants, we think of things that foam and lather, like soaps and body wash. Does that mean there’s soap in your moisturizer or night cream? Not necessarily, but we’ll get to that in a minute. First let’s break down what a surfactant is and how it works.

At a molecular level a surfactant is composed of a hydrophilic (water loving) head and a lipophilic(oil loving) tail. In product formulations surfactants typically take on the form of micelles (micellar water, anyone?). Micelles are spherical particles made up of surfactant molecules that form emulsions between oil and water, but their structure can change depending on the type of emulsion.

In an oil in water emulsion, a micelle will look like this:

Here, the surfactant’s oil loving tail points inward, toward the particle of oil, while the water loving head points outward, surrounding the oil particle so it can mingle nicely with the water and create a stable emulsion.

In a water in oil emulsion, that structure is reversed. These are called reverse micelles:

Here the water loving heads surround the water molecule, allowing it to disperse in oil. These are for products that are mostly oil, like any type of grease, balm, or oil cleanser.

Now, I know what you’re thinking. ‘Mecca I didn’t ask you for this, I wanna know if there’s soap in my night cream.’ That’s up next, calm down.

What makes a surfactant an emulsifier, a detergent, or even a conditioner depends on the ionic charge on that water loving head. There are 4 types.

Cationic (positively charged) – These surfactants are most present in hair conditioners and fabric softeners. The positive charge on the head binds tightly with the keratin in hair and clothing fibers, leaving the tail pointing outward, and any oils or other moisturizing ingredients difficult to rinse away. This is how conditioners are able to keep the hair soft even after it’s rinsed off (most of the time). Because of this, cationic surfactants make very poor cleansers.


  • Behentrimonium chloride
  • Benzalkonium chloride
  • Benzethonium chloride
  • Benzododecinium bromide

Anoinic (negatively charged) – These are your heavy duty cleansers. Soaps, shampoos, body washes, household cleaners, and laundry detergents. These are the reason why your hair feels like shit after using a clarifying shampoo, or why your skin might feel like spongebob in Sandy’s tree dome without a helmet after using certain body washes in the shower. Basically, these can be extremely irritating, especially if you have sensitive skin. But, they make very effective cleansers for other things around the house as well as clothing. The negative charge binds to the positive charge on most dirt, oils, and other things that make you feel gross. If your skin can handle these drill sergeant surfactants, more power to you.


  • sodium lauryl/laureth sulfate
  • ammonium lauryl/dodecyl sulfate
  • potassium lauryl/dodecyl sulfate

Amphoteric/Zwitterionic (dual charged) – These surfactants are able to interact with both positive and negative ions. This also makes them useful as mild cleansers like face washes and baby shampoos. These are sometimes combined with anoinic surfactants to make them more gentle.


  • cocoamido propyl betaine
  • cocoamphoacetate

Nonionic (no charge) – At long last, we’ve arrived. These are the type of surfactants that exist in lotions, creams, serums, and the like. These non-charged surfactants are what we call emulsifiers, as this is their main function. They form a barrier around the oil or water particle we want to emulsify, and make magic. So rest assured, there is no soap in your lotions.


  • polyethylene glycols (PEG-whatevers)
  • polyglycerol alkyl ethers
  • glucosyl dialkyl ethers
  • polyoxyethylene ethers (ceteareth-whatevers)
  • sorbitan esters
  • polysorbates
  • stearic acid


A humectant is a substance that is hygroscopic, which is just a fancy way of saying they draw in and hold onto water. You may hear things about humectants drying out the skin because they don’t discriminate between water in the air and water in the skin. But this shouldn’t be an issue for a few reasons.

First, most lotions have emollient ingredients that seal in whatever water a humectant is holding on to.

Second, the first ingredient in many products is water. Humectants are more than likely already saturated with water by the time they get to you in the form of a cream or lotion.

Third, our bodies are made of mostly water anyway. The deeper layers of skin (dermis and hypodermis) are full of water because they are vascular and the skin is an organ. So let’s say a humectant is pulling water out of those deeper layers. Unless you’re severely dehydrated, or have some kind of condition, those layers have plenty of water to spare since it is constantly being replenished.

The most common humectants in skincare are:

  • Glycerin (glycerol)
  • glycols – propylene glycol, butylene glycol, etc
  • Hyaluronic Acid (Sodium hyaluronate)
  • Honey


Generally, when the term ‘moisturizer’ is used, it’s referring to a finished product. But this post isn’t about finished products, it’s about ingredients. And as far as ingredients are concerned, a moisturizer and an emollient can be considered the same. This is where the difference between moisturizing and hydrating comes in. An ingredient that hydrates adds water, while one that moisturizes seals in that water to keep it from evaporating. These are usually oils (which are pretty easy to identify on ingredient lists), but they can also take the form of fatty alcohols.

Meanwhile, occlusives are basically overpowered moisturizers. They tend to refer to vaseline, waxes, or butters, but even lighter oils can be occlusive depending on your skin type.

  • Petrolatum (Petroleum jelly, vaseline)
  • Mineral oil
  • MCT oil (fractionated coconut oil, capric/caprylic triglycerides)
  • Lanolin
  • Butters (cocoa, Shea, mango)
  • Silicones (simethicone, Dimethicone, trimethicone)
  • Waxes (paraffin, beeswax)
  • Cetearyl alcohol
  • Stearyl alcohol
  • Cetyl alcohol

pH adjusters

Many skincare ingredients are pH dependent. They may become unstable or less effective if the pH of the end product is too low or too high. There are also cases where the pH of a product may be too irritating to the skin, so it needs to be raised or lowered to be more skin friendly. The term ‘acid mantle’ comes to mind. This is because the skin’s pH is 4.5-5.5, slightly acidic, which is why extremely alkaline products are generally avoided by most people or only used in wash off products. This is also why pH adjusting toners have gained popularity since society has learned more about keeping the skin balanced.

That being said, very acidic or very alkaline ingredients are sometimes used to bring the pH of a product up or down. Much like preservatives, these are generally only used at low concentrations. High enough to achieve the desired effect, but too low to cause irritation in most people.


  • Citric acid
  • Lactic acid
  • potassium citrate


  • triethanolamine
  • Lye – sodium hydroxide, caustic soda
  • Potash – potassium hydroxide
  • Baking soda – sodium bicarbonate
  • Borax – sodium borate, disodium tetraborate

Plant extracts

This one probably pisses me off the most about ingredient labels. I understand that companies are required to list a plant extract by its scientific name instead of the common name, but why some don’t put the common name in parenthesis is beyond me. It’s like they want us to feel like idiots or something. Anyway, here are some common plant oils/extracts/etc used in skincare.

  • calendula – Calendula officinalis
  • chamomile – Matricaria chamomilla, Matricaria recutia
  • evening primrose oil – Oenothera biennis
  • green tea – Camellia sinensis
  • jojoba – Simmondsia chinensis
  • lavender – Lavandula
  • lemon – Citrus limon
  • licorice – Glycyrrhiza glabra
  • oat – Avena sativa
  • orange – Citrus × sinensis
  • rice – Oryza sativa, Oryza glaberrima
  • rosehip oil – Rosa canina
  • tea tree oil – Melaleuca alternifolia
  • witch hazel – Hamamelis virginiana


Y’know those things everyone is so afraid of, but are really here to help us? I’ll admit, I try to avoid preservatives in food products as much as I can, but I can still appreciate the convenience of some Ocean Spray cranberry juice that’ll keep in my fridge for 2 weeks over something that’s gonna expire in 3 days if I don’t drink it.

Because that’s what preservatives do. They slow down spoilage and inhibit the growth of microbes. Companies tend to use more than one because the product has to be protected against fungus, bacteria (both gram positive and gram negative), and mold. They fall into these 5 categories:


  • Methylparaben
  • Butylparaben
  • Germaben

Formaldehyde releasers

  • Germall Plus
  • DMDM Hydantoin
  • Imadozolidinyl Urea
  • Diazolidinyl Urea


  • Kathlon


  • Optiphen/Optiphen plus

Organic acids

  • Potassium sorbate/sorbic acid
  • Sodium benzoate/benzoic acid
  • Levulinic Acid
  • Anisic Acid

*Chelating agents

These are not preservatives by themselves but are often used in combination with preservatives to make a product more stable. A chelating agent (pronounced key-late-ing) is a substance that binds with metal ions. Chelation therapy is used to treat heavy metal poisoning because of this mechanism. In skincare, chelating agents are added to prevent metal ions from causing irritation or reacting with other ingredients in the product.

  • disodium EDTA
  • tetrasodium EDTA

Note: Tea tree oil is not a preservative, but it can help reduce the need for higher concentrations of some preservatives. Vitamin E is also not a preservative. It is an antioxidant. They are not the same. Antioxidants delay rancidity due to oxidation, they do not inhibit microbial growth.


Water is often called the universal solvent, but this isn’t always true. There are many substances that do not dissolve in water. While we can use surfactants to emulsify oils in water and vice versa, when we talk about solubility things are a bit different.

This is because solvents and surfactants operate through different processes. Solvents don’t operate by messing with surface tension. They work their magic using polarity to break apart the bonds of whatever is being dissolved.

Salicylic acid, Ferulic acid, and Allantoin are just a few common skincare ingredients that have very poor solubility in water. Here is where other solvents come in.


  • Alcohol (Denatured alcohol, Ethanol, methanol)
  • Glycerol
  • Ethylene glycol
  • Propylene Glycol
  • Butylene Glycol
  • Propanediol
  • Hexanediol

Notice a pattern? The ‘-ol’ in these substances indicates that they are all alcohols. All of em. Even glycerin. What makes alcohol such a great solvent is the fact that it’s polar, but less polar than water. So while alcohol itself dissolves in water, it can dissolve other things water can’t.

Viscosity control

These are usually referred to as thickeners or gelling agents, since thinning out a product usually just means adding more water. Some surfactants can also function as thickeners.


  • Xanthan
  • Guar gum
  • Stearic acid
  • Carbomer


Pretty self explanatory. Vitamins are added to skincare products because some have demonstrated topical benefits.

Vitamin A

  • Retinol**, Retinyl palmitate**, Tretinoin**, retinoic acid**

Vitamin Bs

  • Niacin, Niacinamide, Nicotinamide
  • Panthenol

Vitamin C

  • Ascorbic Acid, L-Ascorbic Acid, Sodium Ascorbyl Phosphate, Magnesium Ascorbyl Phosphate, Ascorbyl Glucoside, Tetrahexyldecyl Ascorbate …basically if you see any word containing ‘ascorb’ it’s probably Vitamin C

Vitamin E

  • Tocopherol, tocopheryl acetate


Additional resources to look at are and Thanks for reading!



Surfactants – Wikipedia

Beta Hydroxy Acids –

Hydroxy Acids, the Most Widely Used Anti-aging Agents – pubmed

Handbook for Cleaning/Decontamination of Surfaces – sciencedirect

Five Most Common Types of Preservatives Used in Cosmetics – microchemlab

Disodium EDTA –

Chelation in Metal Intoxication – pubmed

Alcohols –

Solubilty –

Glycols –

Labeling regulations –

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