In April 2026, the UK Advertising Standards Authority (ASA) issued a ruling against an advertisement by Beiersdorf UK Ltd t/a Eucerin suggesting that a facial serum could make women “look up to five years younger”. The ad further claimed that the effect was clinically proven and that the product was recommended by dermatologists.
The ASA is the UK’s independent regulator of advertising across all media and enforces the Advertising Codes written by the Committees of Advertising Practice (CAP). Its role includes ensuring that advertising claims are truthful, substantiated, and not misleading.
ASA ruling: methodological weaknesses in studies
The evidence submitted comprised four studies and one peer-reviewed research paper.
Overall, the ASA concluded that none of the data provided was sufficiently robust to substantiate the claim that the serum was clinically proven to make users look up to five years younger within four weeks.
Across the studies, the ASA identified recurring methodological weaknesses, including:
- Absence of control groups – Several studies did not include one or more control groups (e.g. a placebo group), making it impossible to determine whether the observed effects were attributable to the product itself or to external factors such as natural skin variation, placebo effect, or changes in skincare habits during the study.
- Lack of blinding – The ASA noted that in some studies it was unclear whether participants, investigators, or assessors were blinded to the treatment they were receiving or reviewing. The absence of blinding increases the risk of conscious or unconscious bias.
- Limited detail on participant selection – Insufficient information was provided regarding participant recruitment, inclusion and exclusion criteria, and the range of skin types included.
- Reliance on subjective, self‑reported outcomes – Several studies relied primarily on participant questionnaires and self‑perceived improvements, such as whether users felt they looked younger. While consumer perception data can provide supporting context, the ASA considered that subjective and self‑reported results alone are not sufficiently robust to substantiate objective or “clinically proven” claims, particularly those implying a quantified age‑reduction effect.
In addition, key results either fell well short of demonstrating a five‑year improvement or failed to measure anti‑ageing effects at all.
ASA also questioned the relevance of the main clinical study to UK consumers, noting that it was conducted in a hotter climate than the UK and provided insufficient information about participants’ skin types, limiting its representativeness of typical UK use. Although a peer-reviewed study was submitted, it related only to the active ingredient rather than the finished product and did not assess real-world use.
Taken together, the ASA found the body of evidence inadequate and concluded that the claims were misleading.
How cosmetic claims are regulated at EU and UK level
Article 20 of the EU Cosmetics Regulation (EC) No 1223/2009 – retained in UK law – states that: “In the labelling, making available on the market and advertising of cosmetic products, text, names, trademarks, pictures and figurative or other signs shall not be used to imply that these products have characteristics or functions which they do not have.”
In addition, Commission Regulation (EU) No 655/2013 establishes common criteria for the justification of cosmetic claims. These criteria require that claims be truthful, honest, supported by adequate evidence, and relevant to the finished cosmetic product.
This ruling highlights the importance of ensuring that claims such as “clinically proven”, “dermatologically tested”, or claims based on consumer perception or clinical trials are supported by well‑designed studies, using appropriate methodologies, relevant population samples, and objective measures.
Do you have questions on how to phrase claims on cosmetics? Contact us here or at coslaw@obelis.net
References
ASA. (2026). ASA Ruling on Beiersdorf UK Ltd. Retrieved on 4 May 2026.
EMA. (2001). Choice of Control Group in Clinical Trials. Retrieved on 4 May 2026.
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