How Serum Formula Percentages Work Together

Turns out it's not as simple as bigger = better.

Meghan Maupin, CEO

CEO of Atolla

Meghan Maupin, CEO

Meg is the CEO and Co-founder of Atolla. She has a graduate degree in Engineering and Management from MIT, and previously worked in design roles at Patagonia, The MIT Design Lab, and Formlabs.



There’s a common misconception that a higher percentage of an active ingredient in a product means it’s a more powerful formula. In fact, a higher percentage isn’t always better. What is important is how different ingredients work together and if they are a good fit to help you reach your skin goals.

What exactly is an “active”?

Active ingredients in a formula deeply penetrate skin to make powerful, lasting changes and address specific skin concerns. Examples include Vitamin C, Retinol, Peptides, Salicylic Acid.

However, usually it’s not just a singular ingredient that is “active” in the formula, but multiple ingredients whose benefits combined make the formulation itself active. Even ingredients that are not considered “active” (like glycerin) are included in skincare formulas to have a beneficial purpose, like enhancing other ingredients' ability to penetrate the skin and maintaining skin’s moisture.

How can ingredients work together?

Many ingredients in skincare are multi-functional and their properties can be enhanced when they are intentionally combined with other ingredients.

For example, Vitamin C is a great ingredient for brightening dark spots, helping with preventative aging, and reducing scarring. As an antioxidant it works well with other antioxidants like Ferulic Acid and Vitamin E, which boost its efficacy and stability. It can also be combined with other actives like Alpha Arbutin or Rumex Occidentalist to double down on specific skin goals like brightening.

When combined with other active ingredients, Vitamin C can be incredibly potent — even at a lower dose. Since Vitamin C is not great for sensitive skin, a recommended approach to add it to your routine is to start off with a lower dose and titrate up.

Given these options,

  1. One serum containing 3% Vitamin C and 2% Alpha Arbutin
  2. Two serums, one 6% Vitamin C and one 2% Alpha Arbutin

it’s actually more effective to choose the first option! When chemists create a skincare formula, they choose ingredients where the whole of the parts is more effective than each ingredient individually. Layering many different products from different brands is much riskier, more expensive, and may not lead to better results.

But isn't bigger better?

Be careful about what’s being claimed on the label. Take Vitamin C for example: this ingredient comes in many forms, including derivatives (ascorbyl palmitate, retinyl ascorbate, tetrahexyldecyl ascorbate, among others). Even if a brand claims 10% Vitamin C, it might only mean 2% pure Vitamin C actually gets absorbed by your skin.

For Atolla formulas, you can view all our principal actives, supporting actives, and base ingredients on our Ingredient Dictionary or reach out to our Atolla Advisor team to better understand how your unique formula was made.

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