What "Clinically Dosed" Actually Means in Skincare

The short answer

"Clinically dosed" means an active is present at the concentration shown to work when tested under clinical conditions. Below that level, an ingredient can be present but not necessarily effective. An ingredient list (INCI) tells you what's in a formula, but it doesn't tell you whether each ingredient is included at an amount that has been clinically tested to deliver results.

An impressive list might do nothing

Most premium serums read beautifully. Peptides, antioxidants, barrier complexes, a paragraph of them.

What the list might not tell you is the amount these ingredients are incuded in your formula. Every active has a concentration at which it was tested and proven to work. Include it at that level and it's functional and effective. If it's only been included to name it on the label, it's inert. The skincare industry has a word for this: fairy-dusting.

"An ingredient present below the concentration at which it was tested is not a functional active. It's simply isted for marketing purposes."

Dr Garry Cussell

How to read the INCI list

Q: Are peptides effective at low concentrations?

A peptide included below its tested concentration acts like a label claim. What matters is the dose the evidence supports, not whether the peptide appears on the list.

Q: How can I tell if a serum is properly dosed?

Look for stated concentrations on the actives that matter, a brand that can explain why a dose was chosen, and meaningful amounts rather than a long list of trace ingredients.

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Ingredients are listed in descending order of concentration down to one percent. Below one percent, they can appear in any order. So a much-promoted active sitting near the end of a long list is almost certainly there in trace.

Order appears high to low, but only down to 1%. Below that, the order tells you nothing.

A named "active" near the bottom of a long list is usually found in a trace amount.

A stated percentage beside an active is a good sign, however this isn't possible on an INCI list.

A very long list is not proof of a great formula. Formulation matters just as much as the active ingredients.

Why brands under-dose

Dosing an active ingredient at the level the evidence supports can cost more, sometimes a great deal more. A trace amount listed can appear on the label at any amount and can still be used for marketing. Especially peptides, antioxidants and the more advanced ingredients.

None of this is a secret to formulators. It's just not something a brand has much reason to spell out. The ingredient is technically there. Whether it's there in a form that does anything is a different question, and not one the label is designed to answer.

What to look for instead

Look for brands that tell you the dose, not just the ingredient. The number on the label matters more than the name.

Rejuvaus formulates most hero actives at the concentration the manufacturer tested, not the minimum needed to justify adding to the INCI list.

Look for the hero ingredients towards the top of the ingredient list. If they sit towards the bottom, they're most likely included at a concentration that isn't effective.

How Rejuvaus formulates

Rejuvaus is built on the maximum dose of actives, held in a safe, microbiome-friendly base designed to perform. Every key peptide, antioxidant and barrier complex is included at the concentration its manufacturer tested and proved.

Dr Cussell, who formulated the range, calls it the only formulation decision that makes clinical sense. It's why the serums are dense with working actives, not a long list of names.

See our formulation percentages

Meaningful concentrations, encapsulated for slow release. The formulation approach behind every Rejuvaus serum.

Explore i·Active™ formulation

Common questions

Reviewed by Dr Garry Cussell, skin specialist.

What does "clinically dosed" mean?

It means an active is present at the concentration shown to work in testing, not merely present. Below that level, an ingredient behaves as a label claim rather than a functional active.

What is fairy-dusting in skincare?

Adding a tiny, below-effective amount of a sought-after active so it can be named on the label, without including enough of it to do anything for the skin.

Does the ingredient order tell you the concentration?

Only partly. Ingredients are listed from highest to lowest concentration down to one percent. Below one percent they can appear in any order, so an active low on a long list is usually a trace.

Are peptides effective at low concentrations?

A peptide included below its tested concentration is just there for marketing. What matters is the dose the evidence supports, not whether the peptide appears on the list.

How can I tell if a serum is properly dosed?

Look for stated concentrations found in brand marketing on the actives that matter. A brand that can explain why a dose was chosen, and meaningful amounts rather than a long list of trace ingredients.