Red-faced at the regulator: ASA spots flaws in Garnier’s 2-week claim

The Advertising Standards Authority (ASA) has upheld a complaint against L'Oréal (UK) Ltd, trading as Garnier, over a Video-On-Demand advertisement for Garnier Vitamin Cg Serum (the serum) claiming that the product was "clinically proven to reduce hyperpigmentation in 2 weeks" (the claim). The ASA found that the evidence provided by Garnier was not sufficiently robust to substantiate the claim, concluding that the advertisement was misleading. The ruling is an illustration of the high evidential bar that the ASA expects advertisers to meet when making objective claims about skincare products. 

The ad

A Video-On-Demand advertisement seen on 28 October 2025 featured a model holding a pack of the serum and applying it to her skin. A close-up of a dark spot on the model's face was highlighted by graphics, and on-screen text included "CLINICALLY PROVEN TO REDUCE HYPERPIGMENTATION IN 2 WEEKS", with small text throughout most of the advertisement stating: "72% of 111 women agree. Clinical study, 44 subjects 10 weeks". A complaint challenged whether the headline claim was misleading and could be substantiated. 

Garnier’s response

Garnier acknowledged that the on-screen qualification was, by error, inaccurate. The intended qualifier for the claim should have read "Clinical study, 44 subjects, 10 weeks", and the phrase "72% of 111 women agree" had been erroneously included. Garnier further acknowledged that the error could have led to consumer confusion between subjective and objective claims. 

In support of the claim, Garnier explained that the product formulation contained ingredients known for their anti-pigmentation effects: niacinamide; ascorbyl glucoside (Vitamin Cg); and Melasyl (L'Oréal's patented molecule) and provided two pieces of supporting evidence. 

The ASA's assessment

The ASA considered that viewers were likely to understand the claim to mean that the product was proven to significantly reduce the visible appearance of dark spots and hyperpigmentation of the skin within two weeks. It therefore expected to see robust evidence to demonstrate that this was the case. The ASA noted Garnier's acknowledgment that the "72% of 111 women agree" qualifier had been included in error but found that this did not change the overall understanding of the claim. 

The ASA found that the evidence submitted by Garnier was not adequate to substantiate the claim, concluding that the advertisement was misleading:

Clinical trial:

The trial looked at the effects of twice-daily use of the serum on dark spots for 10 weeks, to assess the product’s anti-pigmentation effects. The ASA acknowledged that the trial used a device which objectively measured the appearance of dark spots at baseline but identified several limitations: 

• the sample size was small, with no evidence that it was sufficient to be clinically robust;
• the report did not adequately set out the randomisation method for assigning participants to the treatment and control groups;
• the trial was conducted in a country with a hotter, sunnier climate than the UK and with a distribution of skin types that may not have been representative of UK consumers; and
• the trial included protocol requirements to limit UV exposure, but the model was shown outdoors in bright conditions, which the ASA considered inconsistent with how consumers would understand the product needed to be used.

The ASA further acknowledged that whilst the results showed some statistically significant differences after two weeks, the percentage changes were small and seen only amongst a minority of subjects. Although 82% of participants in the clinical study agreed that their dark spots looked less visible after 2 weeks, the ASA considered this a subjective, self-reported result which was not adequate to substantiate a “clinically proven” claim.

Published paper on Melasyl:

This was a placebo-controlled, randomised study that tested three products containing 2-MNG (Melasyl) in 35 people whilst being exposed to UV light. The ASA did not consider the study relevant to substantiate the claim, noting it was designed to test effectiveness in preventing pigmentation, rather than treating established hyperpigmentation. 

CAP Code breaches:

The ASA therefore found that the ad breached the CAP Code because (i) it was misleading, and (ii) Garnier was unable to produce appropriate substantiation, particularly to the high standard required in relation to cosmetic claims.

Key takeaways

1. High evidential bar for “clinically proven” claims: Advertisers should hold robust, well-designed clinical evidence that directly supports the specific claim being made. The ASA will scrutinise whether the sample size, methodology and results are sufficient to support the specific claim made. 
2. Evidence must be directly relevant to the product, the claim and the market: Advertisers should ensure that clinical studies mirror the claim conditions, including timeframe, use case, outcomes measured (e.g. prevention vs treatment). Evidence should be representative of the market, and the ASA will consider whether participant demographics, climate conditions and trial protocols are reflective of typical UK consumer use.
3. On-screen qualifications must be accurate and consistent: Inaccurate or confusing qualifiers, weak study design (e.g. small or unrepresentative samples), and marginal results, even if statistically significant, can undermine substantiation.

CMS has extensive experience advising on borderline cosmetic claims, with experts in both advertising and life sciences. Please get in touch if you have any specific questions on including such claims in your advertising material. 

This article was co-authored by Charlotte Hornshaw, trainee solicitor (secondee) at CMS UK