Ad description

An Instagram post by The INKEY List, posted on their own account on 27 May 2021, for their Caffeine Stimulating Scalp Treatment product. The post’s caption stated, "Caffeine Stimulating Scalp Treatment helps to stimulate hair growth and reduce shedding. Use as an overnight treatment, applying every night for best results! #askINKEY about hair and scalp treatments."

An accompanying image showed the product, and included text which stated, "Helps stimulate growth", "Conditions hair", "Healthy and soft", "Overnight treatment", "Helps reduce thinning" and "Thicker hair goals".


The complainant, a cosmetic chemist, challenged whether the claims "Helps stimulate growth", "Helps reduce thinning" and "Thicker hair goals" were misleading and could be substantiated.


Brand Evangelists for Beauty Ltd said that the Caffeine Stimulating Scalp Treatment product contained an active ingredient called Redensyl, which they said stimulated hair growth by reactivating the hair follicle stem cells and dermal papilla fibroblasts, which interacted with epidermal cells during hair development.

Brand Evangelists provided a scientific file containing reports of the apparent results of Redensyl tests gathered from in vitro assessments, ex vivo assessments, and a clinical investigation. They also provided a document titled “Caffeine Hair Regrowth Treatment Research”, which they said detailed the results of a consumer use test, which they believed supported the claims that the Caffeine Stimulating Scalp Treatment product helped “stimulate growth”, “reduce thinning” and provided “thicker hair”.



The ASA noted that the ad claimed the Caffeine Stimulating Scalp Treatment product would “help stimulate growth” and “reduce thinning”. We considered that consumers would understand the wording of the ad to mean that the product could promote hair growth and reduce hair loss. We also considered that consumers would understand from the text “thicker hair goals” that the product could increase hair thickness. We understood there were a number of different causes of hair loss, and, in the absence of any qualification, we considered the claims in the ad implied that the product could provide those results in both men and women.

Because the claims referred to promoting hair growth and reducing, rather than preventing or curing hair loss, we considered that they would not be understood as medicinal claims. Nonetheless, Brand Evangelists were required to hold adequate evidence to support the claims. We assessed in full the evidence provided.

While we acknowledged that in vitro tests could be useful for research, they could not always be extrapolated to suggest any effects seen would be identical or even similar in vivo. We therefore considered that the results of an in vitro assessment were not sufficient to substantiate the efficacy of the product in human subjects. Furthermore, the ex vivo assessment only included hair taken from two donors. We did not consider that was a suitably large enough sample size to be representative of either the effects of the product, or the UK population.

To support the claim that the product helped stimulate hair growth, Brand Evangelists highlighted a section of the report titled “Clinical investigation of Redensyl” which they said discussed the results of a clinical study conducted for three months on 26 male volunteers suffering from male-pattern baldness. They said the study evaluated the effects of a hair lotion containing 3% Redensyl on the hair loss parameters of the participants after three months of a daily application.

Brand Evangelists believed the study showed that the number of hairs in the anagen phase – the stage of active hair growth - increased by about 9%, whilst the number of hairs in the telogen phase – the final stage of hair growth, during which the hair shaft would be shed - decreased by about 17% over this period. They also said that the report contained photographic evidence based on the trial, which showed a visible reduction in hair thinning, which they believed demonstrated that the active ingredient helped to stimulate hair growth.

When assessing the evidence presented in the clinical investigation section, we noted that the study’s volunteers consisted of 26 males, all of Caucasian or North African descent, aged between 18 and 70. Two groups were selected from that group, with 14 volunteers testing the active ingredient, and 12 volunteers receiving a placebo. Both sets of volunteers applied 3.5 ml of hair lotion to their scalp every day for 84 days, without rinsing after application. The study was randomised and double blinded, and hair parameters were assessed at the start of the assessment, and then after one and three months. The lotion containing the active ingredient used in the study contained 3% Redensyl.

We noted that while the volunteers who made up the study were all men, there was no indication in the ad that the product was targeted only at male consumers. We therefore considered that a study which used a group made up of only male participants contained an insufficient cohort on which to base claims about the efficacy of the product on a broad section of consumers, which was likely to include females, and did not consider that the participants of the study were broadly representative of the makeup of the UK population as a whole.

We also noted that the volunteers completed a self-evaluation questionnaire, and considered that self-reported, subjective responses to such a questionnaire did not constitute adequate evidence to substantiate the claims made in the ad. Furthermore, although the lotion used in the study contained 3% of the active ingredient, the Caffeine Stimulating Scalp Treatment product itself only contained 1% Redensyl. We considered it was important that the claim was based on evidence which used the same formulation as the product.

To support the claim that the product could help reduce hair thinning, Brand Evangelists provided a document titled “Caffeine Hair Regrowth Treatment Research”, which detailed the results of a 51-person consumer use test, conducted between February 2020 and May 2020. The panel consisted of 67% male and 33% female respondents, all aged 35 and over.

We understood that Brand Evangelists believed the claim that the product could help reduce thinning was substantiated by responses from the panel to the question “Does your hair loss look suitably less?”, to which 28 of the 51 participants answered “Yes”. To support the claims that the product could lead to thicker hair, Brand Evangelists again referred to the consumer use test results, and specifically responses to the question “Does your hair feel thicker?”, to which 32 of the 51 participants responded “Yes”. In the self-evaluation of the clinical panel, 64% of respondents agreed that their hair appeared thicker after a 12-week trial.

When assessing the survey, we noted that the results showed that only 55% of respondents thought their hair loss looked suitably lessened, and 63% thought their hair felt thicker. The study did not show there was a statistically significant difference between participants responding positively or negatively to those questions. In any case, in the absence of more objective data demonstrating the effect, we did not consider that consumer perception data, and the self-evaluation section of the clinical study, was sufficient to support the claims that the product could reduce thinning and lead to thicker hair.

Because we considered that the evidence provided was inadequate substantiation for the efficacy claims relating to the products ability to promote hair growth, reduce thinning and lead to thicker hair, we concluded the ad was misleading.

The claims breached CAP Code (Edition 12) rules  3.1 3.1 Marketing communications must not materially mislead or be likely to do so.  (Misleading advertising),  3.7 3.7 Before distributing or submitting a marketing communication for publication, marketers must hold documentary evidence to prove claims that consumers are likely to regard as objective and that are capable of objective substantiation. The ASA may regard claims as misleading in the absence of adequate substantiation.  (Substantiation) and  12.23 12.23 Marketers must be able to provide scientific evidence, if relevant consisting of trials conducted on people, for any claim that their product or therapy can prevent baldness or slow it down, arrest or reverse hair loss, stimulate or improve hair growth, nourish hair roots, strengthen the hair or improve its health as distinct from its appearance.  (Hair and scalp).


The ad must not appear again in the form complained of. We told Brand Evangelists for Beauty Ltd not to state or imply that their product could promote hair growth, help reduce thinning and lead to thicker hair unless they held adequate evidence to support their claims.

CAP Code (Edition 12)

3.1     3.7     12.23    

More on