We have anonymised the products as Bottle A, B and C. The point is not to crown a brand but to show a method you can repeat in any shop aisle with nothing more than a phone torch and patience. All three are 30 ml serums. One costs three times as much as the cheapest. All three carry the same phrase on the front.
Step one: find the active, then find its neighbours
Bottle A lists ascorbic acid third, after water and propylene glycol, followed by tocopherol and ferulic acid. That pattern is consistent with a classic high-strength vitamin C serum, and the brand states 15%.
Bottle B lists niacinamide second, then tranexamic acid and a small amount of zinc PCA. The front says 10% niacinamide, which matches its position.
Bottle C, the expensive one, leads with water, glycerin, a botanical water, and a silicone. Its headline “vitamin C complex” — ascorbyl glucoside — appears after phenoxyethanol. Its “brightening peptide” appears after the fragrance.
“If the hero of the advertisement sits after the preservative, you are paying for its name, not its dose.”
| Measure | Bottle A | Bottle B | Bottle C |
|---|---|---|---|
| Lead active | Ascorbic acid, stated 15% | Niacinamide, stated 10% | Ascorbyl glucoside, unstated |
| Position on list | 3rd | 2nd | After phenoxyethanol |
| Supporting actives | Tocopherol, ferulic acid | Tranexamic acid, zinc PCA | Peptide after parfum |
| Formula pH | About 3.0–3.2 | About 5.5–6.0 | Not disclosed |
| Packaging | Amber glass, dropper | Opaque airless pump | Clear glass, dropper |
| Fragrance | None | None | Parfum, plus limonene and linalool |
| Likely to sting | Yes, at first | Rarely | Possibly, from fragrance |
| Relative price | £££ | £ | £££££ |
Step two: check whether the formula lets the active work
Ascorbic acid needs a low pH to penetrate; Bottle A's acidity is a feature, not a flaw. Niacinamide is happy near skin's natural pH, which is why Bottle B can be gentle. Bottle C does not disclose pH, which is normal — few brands do — but its glucoside derivative is so far down the list that the question hardly matters.
Step three: look at the packaging as an ingredient
Ascorbic acid and retinoids degrade with light and oxygen. Amber glass slows light damage; an airless pump also limits air. A clear dropper bottle, as on Bottle C, is the worst arrangement for a sensitive active, though it photographs beautifully. Packaging is one of the few places where a higher price can genuinely buy performance, and Bottle C does not spend it there.
Step four: translate “clinically proven”
In both the EU and the UK, cosmetic claims must meet common criteria set out in Commission Regulation (EU) No 655/2013, including truthfulness and evidential support. In practice, “clinically proven” can describe a consumer perception study of 30 volunteers who answered a questionnaire. Bottle C's footnote reads “in a self-assessment of 22 women after 28 days”. That is a survey about feelings, not a measurement of skin.
Bottle A's brand cites the published vitamin C, E and ferulic literature, which is real but was not conducted on their product. Bottle B makes no clinical claim at all, beyond the active percentages. Of the three, the quietest label made the most verifiable statements.
What we would buy, and why that is beside the point
For brightening, Bottle B is the low-risk choice and Bottle A the stronger but fussier one. Bottle C may be pleasant to use; there is nothing wrong with paying for pleasure, provided you know that is what you are buying. The method generalises: identify the active, find its position, check the formula and the pack, then read the footnote under the claim.
To decode the remaining parts of the label — allergens, symbols, and “free-from” lists — continue to Reading the Back of the Jar.