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Start journey Learn moreWhy this question matters, and what the facts say about diluting semaglutide in the UK
The misconception worth correcting: that diluting semaglutide is a normal part of treatment
It is not. This is the single most important thing to say clearly, and then let it go.
The idea that patients need to mix or dilute semaglutide before injecting it has spread through online forums and social media communities, where unlicensed, compounded semaglutide vials (usually supplied as a freeze-dried powder or a concentrated liquid) are discussed as though they are an ordinary alternative to the branded product. They are not. In the UK, the MHRA licenses semaglutide for weight management under the brand name Wegovy, supplied as a pre-filled injection pen with each dose factory-set. There is nothing to prepare, measure or reconstitute.
If a product you have been sold requires dilution before injection, that is a signal about the product itself, not a technique to master. The Wegovy injection as prescribed through a regulated UK pharmacy arrives ready to use. Patients following the licensed treatment pathway do not encounter this step at all. If you are curious about what a properly supervised start to semaglutide treatment looks like, the guide to starting semaglutide covers that in full.
What goes wrong when people try to dilute semaglutide themselves
The risks are not theoretical. Diluting a concentrated substance at home introduces several serious possibilities for error: using the wrong diluent, miscalculating the volume, drawing an inaccurate dose from a vial, or contaminating the solution during preparation. Each of these can result in receiving far too little (making treatment ineffective) or far too much, which carries risks including severe gastrointestinal illness, dangerously low blood pressure, or worse.
Beyond dosing arithmetic, there is the question of what is actually in the vial. The MHRA has seized large quantities of fake and unlicensed weight-loss medicines, some of which contained insulin rather than semaglutide. Insulin injected by someone who does not need it and is not monitoring blood glucose can cause life-threatening hypoglycaemia. Reporting concerns about suspect products can be done through the MHRA Yellow Card scheme, which accepts reports from patients as well as healthcare professionals.
The short version: the dilution step is not a skill gap. It is a red flag about the product's origin. If you have encountered instructions telling you how to dilute semaglutide, our semaglutide dilution calculator page explains why that process exists and what it says about the product you have been supplied, and our semaglutide controversy page explores the wider context of unlicensed products in more detail.
What to do instead, and how licensed treatment actually works
Licensed Wegovy is available in the UK through a private prescription from a GPhC-registered pharmacy or, for eligible patients, via NHS specialist weight management services. The NHS semaglutide medicines page outlines how the medicine works and what to expect.
At nume, every consultation is read by a GPhC-registered Independent Prescriber (a real clinician, not an automated system) on the same day you submit it. If treatment is clinically suitable, the licensed product is dispatched the same day for free next-working-day delivery by DPD, in plain packaging. Nothing to mix. Nothing to measure.
For context on what treatment costs through a legitimate private provider, the Wegovy cost page sets out what a transparent private price includes and why the headline figure from an unlicensed seller is rarely a fair comparison. The licensed medicine, clinical oversight and genuine supply chain are part of what you are paying for.
If you are already on treatment and have questions about managing your dose, what stopping looks like, or anything in between, our frequently asked questions are a good starting point, and our clinical team is reachable seven days a week. There is no need to find workarounds when the straightforward, legal route is this accessible.
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