The UK medicines regulator is investigating whether clinics are breaking the law by making health claims about unregulated, experimental peptide therapies that lack solid scientific evidence in humans. The Medicines and Healthcare products Regulatory Agency (MHRA) has found multiple clinics operating across the UK offering peptides like BPC-157, MOTS-C, and Thymosin Alpha while claiming they aid everything from tissue repair to immune function, despite minimal human clinical trials to back these claims .

What Are Peptides and Why Are They Suddenly Everywhere?

Peptides are short chains of amino acids, some of which occur naturally in the body. Insulin, for example, is a peptide hormone that helps regulate blood sugar. In recent years, interest in experimental peptides has boomed, with clinics and influencers touting them for weight loss, anti-aging, injury recovery, and immune support .

The confusion stems partly from the success of approved weight-loss medications based on synthetic peptides. Semaglutide (found in Wegovy) and tirzepatide (found in Mounjaro) are peptide-based drugs that have undergone strict regulatory approval. However, many other peptides on the market have not undergone this rigorous testing and remain experimental .

What Health Claims Are These Clinics Actually Making?

A Guardian investigation uncovered several UK clinics making medicinal claims for unregulated peptides on their websites. One top-ranked clinic stated 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." After the Guardian approached the clinic for comment, it deleted these claims from its site .

Another clinic advertised seven named peptides with pricing and "results duration" despite labeling them as "research only." The clinic charged around 350 British pounds per month for a single peptide and 450 British pounds per month for two peptides, delivered either in vials with disposable syringes or in pre-loaded injection pens .

What Does the Regulator Say About This?

The MHRA has made clear that clinics are not permitted to make medicinal claims for peptide treatments. According to the regulator, if clinics make medicinal claims, the products are considered medicines and must be subject to regulation under the Human Medicines Regulations 2012 .

"If clinics offering peptide injections make medicinal claims for those treatments, the products will be considered medicines and subject to regulation under the Human Medicines Regulations 2012. The MHRA will take action against clinics which are identified as breaching the legal requirements," stated an MHRA spokesperson.

MHRA Spokesperson, Medicines and Healthcare products Regulatory Agency

The regulator defines a medicinal product as "any substance or combination of substances presented as having properties of preventing or treating disease in human beings." This includes any substance that may be used to restore, correct, or modify a physiological function by exerting a pharmacological, immunological, or metabolic action .

How to Evaluate Peptide Clinic Claims Before Considering Treatment

• Check for Clinical Evidence: Ask the clinic for peer-reviewed human studies, not just animal or cell research. Most peptides currently marketed lack large-scale randomized controlled trials assessing long-term outcomes in people.
• Verify Regulatory Status: Confirm whether the peptide is an approved medicine or an experimental substance. Approved weight-loss peptides like semaglutide and tirzepatide have undergone strict regulatory review; most others have not.
• Be Wary of "Research Only" Labels: The MHRA disregards claims that products are for "research purposes" if promotional material suggests they are actually intended for human use. This is a common loophole clinics use to avoid medicines regulations.
• Ask About Safety Monitoring: Legitimate clinics should explain potential risks and recommend monitoring periods. One clinic advised taking four to eight weeks off between two to three month periods of peptide use to reduce risks, though even this guidance lacks robust evidence.

What Did Clinicians Tell Undercover Investigators?

When a Guardian reporter conducted a free consultation with one clinic, the clinician acknowledged that most research into peptides was pre-clinical and some peptides were still very experimental. The clinician also noted there was a lack of randomized multi-center clinical trials for peptides to provide information about their long-term effects .

Despite these limitations, the clinician recommended the reporter consider taking BPC-157 and MOTS-C. For BPC-157, the clinician explained it "helps in repair and recovery of cells" and provides "more blood flow and nutrients to different tissues that need repair," promoting "quicker recovery from whatever physical activity that you've done." However, the clinician cautioned that BPC-157 was not advised for people who smoke or have a family history of cancer, as there were concerns the peptide could increase blood supply to such tissue and potentially fuel cancer growth .

For MOTS-C, the clinician claimed it "helps provide more stress resilience and better health to your mitochondria to be able to produce more energy cells," with the net effect being "reduced insulin resistance, better energy production," and ultimately "reduce visceral fat." The MHRA said it was investigating whether these claims constituted unlawful medicinal claims .

Why Is This Happening Now?

The peptide boom reflects a broader trend of people seeking wellness solutions outside traditional medical channels. One clinic acknowledged that "a significant number of individuals in the UK are already accessing peptide products through unregulated channels, including informal online networks such as messaging platforms, where there is little to no clinical oversight, quality assurance, or safety screening." The clinic argued that offering regulated consultations was preferable to people obtaining peptides through completely unmonitored sources .

However, the MHRA's position is clear: unregulated peptides should not be marketed with health claims, regardless of the reasoning. The regulator emphasized that it determines whether a product is a medicine on a case-by-case basis, considering the product's effect on the body, how it is used, and all available evidence .

What Should Women Know About GLP-1 Peptides and Fertility?

While approved GLP-1 peptide medications like semaglutide have been studied for weight loss and metabolic health, the unregulated peptides being marketed by these clinics have not undergone the same scrutiny. Women considering any peptide therapy, especially those planning pregnancy or managing conditions like polycystic ovary syndrome (PCOS), should consult with a licensed healthcare provider rather than relying on clinic consultations that lack robust clinical evidence .

The key takeaway is straightforward: if a peptide therapy sounds too good to be true and lacks published human clinical trials, it probably is. The MHRA's investigation signals that the era of unregulated peptide marketing may be coming to an end, but women and other consumers should remain cautious about any clinic making bold health claims without solid evidence to back them up.