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On 22 April 2026, the Advertising Standards Authority (ASA) upheld a ruling on a misleading claim against a skin serum which claimed it was clinically proven to reduce hyperpigmentation in two weeks.
The CAP code states that before distributing or submitting a marketing communication for publication, marketers must hold documentary evidence to prove claims that consumers would likely regard as objective and that are capable of objective substantiation. Objective claims must be substantiated by evidence, if relevant consisting of trials conducted on people.
The ASA acknowledged that the claim was based on a 10-week clinical study, with objective measurements of the appearance of dark spots taken at baseline, two weeks and ten weeks. However, they considered there to be limitations to the study, including the sample size, as well as there being no evidence in the trial report to support whether the sample size used was big enough to be considered clinically robust.
The ASA also questioned how representative the trial was to typical UK use, due to the trial being conducted in a country with a hotter, sunnier climate than the UK and different participant characteristics in terms of skin type. ASA considered the distribution of different skin types in participants of the trial to be different from the distribution of skin types expected to be seen in the UK. Moreover, the protocol requirements within the trial were seen as not reflective of how consumers would have understood to use the product from the ad, thus reducing the extent the results could be taken as directly representative of typical use by the UK consumer.
Whilst the results showed statistically significant differences, the ASA considered that some of the evidence was based on subjective, self-reported results which were not adequate to substantiate a ‘clinically proven’ claim.
Therefore, ASA concluded that the evidence was not adequate to substantiate the claim in question and thus breached the CAP code. The ad must not appear again in this current form, and the brand must not state or imply the above claim unless there is robust evidence in place to substantiate the claim.
