A good formula.
More than HA.
Five checks before paying a premium.
Compare the same amount
Price per mL makes bottle sizes easier to compare. It does not measure effectiveness. Prices here use US one-time purchase listings, not subscription discounts.
Separate concentration from molecular size
A percentage tells you how much is claimed, while kDa describes molecular mass. “Multi-weight” alone tells you neither the exact distribution nor that it matches a trial.
Look at the supporting formula
Humectants such as glycerin help attract water. A serum’s other ingredients and your moisturiser also affect the result. Do not treat a study of one ingredient as a trial of the whole bottle.
Read the type of evidence
A controlled trial compares against a base formula or another treatment. An open-label before-and-after study cannot separate every cause of improvement. Lab measurements and user surveys are useful context, but answer different questions.
Make room for tolerance
Fragrance, aromatic oils and other ingredients can matter to people with sensitivities. A premium price is not a tolerance guarantee. Check the current package, follow its instructions and stop if irritation persists. A serum does not replace sunscreen.