MHRA Probes UK Peptide Therapy Claims

The Medicines and Healthcare products Regulatory Agency (MHRA) is investigating whether clinics in the United Kingdom are breaking the law by making claims about the benefits of unregulated and experimental peptide therapies.

The investigation follows a report by the Guardian on April 4, 2026, which found several clinics offering a variety of experimental peptides and promoting their health benefits on their websites.

The MHRA has stated that clinics are not permitted to make medicinal claims for peptide treatments offered through their services. According to an MHRA spokesperson, if clinics make such claims, the products are considered medicines and are subject to regulation under the Human Medicines Regulations 2012.

The MHRA will take action against clinics which are identified as breaching the legal requirements.

MHRA spokesperson

Unregulated Health Claims

The Guardian investigation identified specific claims made by one of the top Google search results for peptide clinics in the UK. The clinic’s website claimed that Cortexin is used for neuroprotection and cognitive enhancement, that BPC-157 aids in tissue repair and recovery from injuries, and that Thymosin Alpha boosts immune function.

The MHRA confirmed that such websites were making medicinal claims for the treatments being offered, which is not permitted. Following contact from the Guardian, the clinic in question deleted the claims from its website.

Interest in these experimental peptides has increased in recent years. The substances are delivered via injection and are promoted by influencers, sellers, and some medical professionals as treatments for anti-ageing, weight loss, mood improvement, and recovery from injury.

Understanding Peptides

Peptides are short chains of amino acids. Some occur naturally within the human body to perform specific functions. Examples include the hormones oxytocin, which is involved in social behaviours, and vasopressin, which regulates blood pressure and water retention. Insulin is another natural peptide used to regulate blood sugar levels. Other peptides are formed naturally when the body breaks down proteins during digestion.

There is a distinction between approved medicinal peptides and the experimental versions currently under investigation. Some synthetic peptides that mimic natural hormones have undergone strict regulatory processes and are available as approved prescription medications, such as tirzepatide (found in Mounjaro) and semaglutide (found in Wegovy), both used for weight loss.

In contrast, many peptides currently on the market have not undergone these regulatory processes. These unregulated, experimental peptides are often sold for self-injection.

Lack of Scientific Evidence

Despite the claims made by high-profile figures, including athletes and influencers, there is little scientific evidence to support health and wellness claims regarding these experimental peptides in humans.

Where studies have been conducted on these substances, the majority have been carried out using cells or animals rather than human subjects.