Active Ingredients and Their Concentrations (Part 2 of 2)

Active Ingredients and Their Concentrations (Part 2 of 2)

Though it may seem simple at first glance, decoding a beauty product’s ingredients label can be a tricky task. In PART 1, we went over label basics like the order of ingredients and the 1% line. We also briefly mentioned active ingredients and how it’s a common misconception that higher concentrations of active ingredients means better efficacy and faster results. With that in mind, let’s look into active ingredients. Are products still effective if the active ingredient is below the 1% line? Are higher concentrations always better?

This is a super helpful way of denoting the amounts of any substance because you know exactly how much you’re getting regardless of different volumes because it already takes volume into account. 

Think of it this way: you have lemonade in a pitcher and it’s made up of sugar, lemon juice, and water. If you pour it into a smaller glass, the concentrations of each ingredient don’t change. It tastes the exact same regardless of the volume you pour into the glass! 

concentration explained


Percent Concentrations

In the cosmetics industry, concentrations of ingredients are reported (if they are reported at all) as percentages. More specifically, they’re reported as weight percentages. When working with percent concentrations, there are three common ways to report it: volume per volume (v/v), weight per volume (w/v), and weight per weight (w/w). 

volume per volume (v/v):

Volume concentration, or volume per volume (v/v), is mainly used for solutions that are made up of liquids. Let’s look at lemonade as an example. If you have 100 mL of lemonade that is made up of 30 mL sugar syrup, 20 mL of lemon juice, and 50 mL of water, the concentration of each ingredient would be 30% sugar syrup v/v, 20% lemon juice v/v, and 50% water v/v. Pretty straightforward! 

What if one of the ingredients was not a liquid?

weight per volume (w/v):

If you have a single solution that is dissolving several different solid ingredients, then mass concentration, or weight per volume (w/v), might be used to denote concentration. 

Though this may seem like an easy calculation at first, it’s difficult to accurately report mass concentrations because density has to be taken into account. For example, let’s say you’re dissolving 400 g of compound x into 600 mL of water to make 1000 g of a final solution. Let’s also say that the density of the final solution is 0.98. The final mass concentration is not 40% of compound x, but rather 39.2% w/v because it must be multiplied by the final density. 

So, if it’s that complicated to report mass concentration accurately, why use it at all? In biological sciences, we oftentimes have incredibly small amounts of solid compounds dissolved in water. Because water’s density is 1, and the small amounts of dissolved compounds are most likely not changing the density, scientists can get away with using % w/v as an easy way to keep track of concentrations. 

weight per weight (w/w):

This brings us to weight percent (w/w) which is what cosmetic products use to report concentration. For this measurement, volume measurements are ignored regardless of if components are liquids, and rather, only the weights are used. Let’s go back to the lemonade example: if you have 20 g of sugar, 30 g of lemon juice, and 50 g of water to make a total 100 g of lemonade, the weight percent of each ingredient is 20% sugar w/w, 30% milk w/w, and 50% water w/w. 

The Dose Makes the Poison

Concentrations are not only important in an ingredient’s efficacy, but also their safety. In fact, a substance’s toxicity is reliant on its concentration. If you’ve heard the phrase “the dose makes the poison,” it’s in reference to this. 

Anything can be poisonous at high enough concentrations or with prolonged exposure. In the world of science, we don’t categorize compounds as “good” or “bad,” but rather look at the toxicity in reference to concentration. There are certainly very toxic compounds where even exposure to small amounts can be harmful, but there are others (especially in formulation chemistry) that may be irritating or toxic at extremely high concentrations, but are otherwise completely safe. Take something as common as salt. The average American consumes 2300-3400 mg per day without keeling over and dying immediately. However, copious amounts taken at once can kill you in a phenomenon known as salt poisoning. That doesn’t mean salt is innately “bad” or “toxic” and must be avoided at all costs. In fact it’s quite the opposite. You need some salt in your diet to be healthy. 

You might be thinking, how does this relate to active ingredients in cosmetic and personal care products? Well, like most things, too much of a good thing can be a bad thing - even your favorite cosmetic active ingredients. The concentration, AKA dose, of the active ingredient(s) can make or break products and more is not necessarily better.

More is NOT Always Better

So, you’ve found the approximate 1% in a product you’re interested in, what next? For more information on active ingredients, check out PART 1 of our Reading Ingredients Labels. 

To quickly recap - active ingredients are the components of a formula (drug, cosmetic, personal care product) that is functionally active. It’s essentially the ingredient that is going to perform the task that the product claims it does. Though it’s easy to make a generalized assumption that active ingredients below the 1% line are not effective, that is not always the case. To take it a step further, there’s been a recent trend for cosmetic companies to increase their active ingredient concentrations to unnecessary, and sometimes even harmful levels. This practice of “concentration chasing” is not always beneficial.


For example, let’s look at retinol. Retinol has become a household name in the world of skincare and for good reason! For decades, it’s been a tried and true ingredient for reducing the appearance of fine wrinkles and for fighting acne. However, retinol should ONLY be used between 0.1-1.0% to avoid severe side effects like irritation, flaking, and dryness. 

On top of that, many skincare experts say to stick with 0.1-0.3% which is well below the 1% line. On a slight tangent, even some other popular active ingredients that are above the 1% line have been subject to unnecessary concentration hikes (accompanied with higher prices) by various brands in the past few years. Take niacinamide for example. When used at 2-4% w/w, niacinamide is an effective skincare ingredient for concerns like skin barrier, pigmentation, and sebum regulation. However, some newer serums may contain up to 10% niacinamide, which isn’t necessarily harmful (though you might want to be careful if you have sensitive skin) but also isn’t any more helpful than the 2-4% range.  

ProCelinyl is Below the 1% Line

So to address the elephant in the room, yes, ProCelinyl is formulated below 1%. And this was an intentional decision on our part. Our rigorous studies showed the efficacy and safety of ProCelinyl. Though we are constantly trying to improve formulation, we want to be sure we’re delivering the best possible results without compromising safety or having unnecessary amounts of ProCelinyl. For more information regarding ProCelinyl, including its discovery process, please check out our white paper.

TL;DR: A Summary of How to Read an Ingredients Label on a Cosmetic Product

summary of active ingredients
Profile photo for David Zhang

Reviewed by: David Zhang, PhD

David is an immunologist and bioengineer with over a decade of medical research experience. He completed his PhD at Harvard University, where he worked on developing life-saving cancer therapies. He received his undergraduate degree in immunology from McGill University and his master's degree from the University of Toronto

Written by: Revela Editorial Team

Previous Blog Next Blog


Minoxidil vs. ProCelinyl™: A Tale of Two Serums

When it comes to treating hair loss, unexpected and repurposed ingredients constantly pop up with claims to regrow hair at a fraction of the cost. The reality is that if...

Skin Elasticity: The “Secret” to Tone & Lift

Fine lines and wrinkles are a hot topic across the entire skin care community, especially in anti-aging products. While these two telltale signs become more pronounced as we age, one...

From Nutraceuticals to Drugs, We Are What We Eat

When it comes to managing health issues, whether hair loss or something else entirely, it makes sense to take a look at the fuel we put into our bodies. Are...