What Would Make Me Believe Your “Clinically Proven” Claim?

When I read “clinically proven” on a skincare bottle, I want to know what I can reasonably expect from using it.

Will the change be visible? How long will it take? Was the product tested on people with the concern I am buying it for?

Those are the questions I want the evidence to answer.

In 2014, L'Oréal USA agreed to settle Federal Trade Commission charges over claims for Lancôme Génifique and L'Oréal Paris Youth Code. According to the FTC, the disputed advertising included claims that the products targeted genes to deliver younger looking skin, and the agency said the company could not substantiate them. That case concerns specific advertising at the time, not every product the company sells today.

For me, the lesson is simple: a familiar name cannot answer a question about evidence.

Here is what would increase my confidence.

Was it the finished serum, an ingredient, or a routine containing several products?

Evidence needs to fit the formula, use and benefit being advertised. According to the FTC's Health Products Compliance Guidance, a study on an ingredient does not automatically establish the same result for every product that contains it. The substantiation has to match the specific claim being made.

• My question: “Can you share the study supporting this exact product claim?”

“90% agreed their skin felt smoother” and “a 90% reduction in wrinkles” describe different things.

The first reports people's opinions. The second claims a measured reduction. Consumer feedback can support an appropriately worded perception claim, but it cannot substitute for evidence of an objective effect. The UK advertising regulators, the ASA and CAP, explicitly warn against presenting a satisfaction survey as if it proved a physical result.

• My question: “Is that number the percentage of people who agreed, or the size of the improvement?”

Improvement from the starting point alone does not establish how much the product caused. An appropriate comparison helps separate the product's effect from other changes.

Research on evidence quality points the same way: random allocation, and keeping participants or assessors unaware of who received the treatment where feasible, further reduce bias. The FTC's guidance is clear that the design should suit the claim, and that well controlled human testing is the standard it expects for objective efficacy claims.

• My question: “Better compared with what?”

I want the participant numbers, their relevant skin characteristics, the study duration and the usage instructions.

There is no single participant count that makes every study convincing. As the FTC guidance notes, sample size and duration need to suit the question, and a statistically significant finding still needs to deliver a meaningful benefit to matter in real use.

• My question: “What improvement could someone with my concern realistically expect?”

If the evidence concerns a temporary change in appearance, I want that limitation stated clearly.

Before and after photographs should not exaggerate the effect through lighting or retouching. UK cosmetics guidance from the ASA and CAP specifically addresses both exaggerated imagery and the distinction between a temporary cosmetic effect and a more lasting physiological one.

• My question: “What exactly improved, and how long was that improvement observed?”

I would like a short public summary naming the testing organisation, who funded the work, what was measured, the results and the limitations.

I would also ask how many participants stopped using the product and whether irritation was recorded.

These are my transparency expectations. An unavailable public report does not, by itself, prove a claim is false. It does leave me with less information to judge it.

• My question: “Who ran the test, who paid for it, and where can I read a plain summary?”

The one message I would send before buying

Before my next purchase, I would send one message:

“Could you share a plain language summary of the study behind this claim, including the product tested, participant numbers, comparison, duration, measured results and any reported reactions?”

I should not need research training to understand the promise on a bottle.

If “clinically proven” is part of the reason I should buy it, understanding what was proven should be part of the buying experience.

Sources and further reading

This is an opinion piece written from a consumer's point of view. The regulatory principles referenced below are summarised from published guidance by the named authorities; the specific wording and requirements should be confirmed against the originals.

1. 1U.S. Federal Trade Commission (2014), “L'Oréal Settles FTC Charges Alleging Deceptive Advertising for Anti-Aging Cosmetics.” The FTC said L'Oréal could not substantiate claims that Lancôme Génifique and L'Oréal Paris Youth Code targeted genes to produce visibly younger skin. View source
2. 2U.S. Federal Trade Commission, “FTC Policy Statement Regarding Advertising Substantiation.” Advertisers must have a reasonable basis for a claim before making it; express proof claims such as “tests prove” or “studies show” require at least the advertised level of substantiation. View source
3. 3U.S. Federal Trade Commission (2022), “Health Products Compliance Guidance.” Sets out the “competent and reliable scientific evidence” standard, why evidence must match the specific claim and product, and the role of well controlled human testing. View source
4. 4ASA and CAP (UK advertising regulators), “Beauty and Cosmetics: General.” Marketers must hold evidence for efficacy claims and must not exaggerate a product's effects through implied claims or imagery. View source
5. 5ASA and CAP, “Beauty and Cosmetics: Physiological effect.” Explains the distinction between a temporary cosmetic effect and a more lasting physiological change, and the evidence each requires. View source
6. 6ASA and CAP, “Beauty and Cosmetics: The use of production techniques.” Guidance on before and after imagery, retouching and post-production that could exaggerate a product's apparent performance. View source

Hero image courtesy of Unsplash and its photographer, used under the Unsplash License.