Weight control: Pills, medicines and patches

Jun 26th '24

Prescription-only medicines (POMs)

Medicines should not be advertised to the public unless the marketer holds a valid licence, marketing authorisation or registration and claims in ads should conform to the authorisation. Marketers should refer to the Medicines and Healthcare products Regulatory Agency (MHRA) for advice.


Prescription-only medicines (POMs) are a specific class of medicine. A POM has to be prescribed by a doctor or other authorised health professional and it has to be dispensed from a pharmacy or from another specifically licensed place.


Prescription-only medicines (POMs) cannot be advertised to the public.


Following an influx of complaints about ads for POM treatments for weight-loss in 2020, Committee of Advertising Practice (CAP) issued an enforcement notice against marketers advertising the medicine to the public.


Medicines, Medical devices and Traditional Herbal Remedies

Marketers should neither state or imply they are offering medicines if they are not (nor imply products have been clinically tested or medically approved if they have not Lipstick Gangster Ltd, 12 July 2023)


For products that have been authorised by the MHRA, advertised claims should not exceed those specified in the marketing authorisation. The Advertising Standards Authority (ASA) has previously upheld complaints against and ad for a herbal remedy, despite the MHRA authorisation of the product, because the claims in the ad went further than the marketing authorisation allowed.



Marketers should bear in mind that any ingested products that claim to affect metabolism may be medicinal and therefore prohibited by rule 12.11, unless licensed by the Medicines and Healthcare products Regulatory Agency (MHRA). Claims such as “decrease appetite”, “burn fat” and “speed up metabolism” are likely to be medicinal and should not be made for unauthorised products. Marketers for slimming products that make such claims should first consult the MHRA to ensure their claims do not breach the medicines regulations.



CAP is aware of unlicensed slimming pills, herbal remedies and patches that purport to aid weight loss. Neither CAP nor the ASA has seen convincing evidence that such unlicensed products can result in weight loss (Liquid Lipo Ltd, 18 May 2022).


‘Breakthrough’ or new claims should be supported by a body of evidence, not just one study.


Objective claims, whether direct or implied, in ads for weight control products must be backed by evidence.  Usually this means a body of evidence including trials conducted on people (Lipstick Gangster Ltd, 12 July 2023).  Full details of the type of evidence the ASA expects to see is available here: Substantiation for health, beauty and slimming claims.


  • Fat binders

While some marketers refer to fat binders as “supplements”, if the product is classed as a medical device, it will not also be considered a food for the purpose of the CAP Code. Therefore, marketers should ensure that they hold rigorous product specific scientific data, which proves that a medical device which acts as fat binder can work as described. See Weight control: Fat binders and Weight control: chitosan.


If the product is not classed as a medical device, the product is likely to be a food supplement and therefore the Food Rules (section 15) will apply in addition to any relevant Weight Control and Slimming rules (section 13). Weight loss claims are considered to be health claims and are only permitted if they are authorised on the GB (NHC) Register. See Weight control: Food and Food supplements and Food: Health claims.



The ASA upheld complaints that an ad for a slimming patch made medicinal claims for a product that was not licensed as a medicinal product.  It also ruled that efficacy claims made in the ad, including several in testimonials had not been proven. Rates of weight loss referred to in the ad, including in before and after photos and testimonials were unlikely to be compatible with good medical and nutritional practice (Easylife Group Ltd, 23 December 2020).  See Weight control: Testimonials and Before and after photos.


Similar unproven weight loss claims were made for an amber foot patch (UAB BeWell EU. 12 October 2022) and a belly slimming patch (Chengyi Daily Department Store, 1 November 2023).  The ASA ruled that the latter was socially irresponsible because it encouraged people to aspire to be dangerously thin and encouraged them to but unlicensed and potentially unsafe products.


Patches may be advertised on an availability-only platform or may be advertised as being a prompt to remind wearers to stick to their diets. No efficacy claims should be made.



Obesity is frequently associated with medical conditions and ad rules which state that marketers should not offer specific advice on, diagnosis of or treatment for it unless it is conducted under the supervision of a medical doctor or other suitably qualified health professional. See Weight Control: Obesity.


Source: CAP


About CAP

The CAP is the sister organisation of the Advertising Standards Authority (ASA) and is responsible for writing the Advertising Codes.


Note: This advice is given by the CAP Executive about non-broadcast advertising. It does not constitute legal advice. It does not bind CAP, CAP advisory panels or the ASA. CAP’s AdviceOnline entries provide guidance on interpreting the UK Code of Non-broadcast Advertising and Direct & Promotional Marketing.


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