Thinking about mixing your own semaglutide? Read this first

The decision many people are actually facing

Cost is usually the driver. Wegovy has a real price tag in private practice, and when someone spots a vial of powder labelled "semaglutide" selling online for a fraction of the cost, the arithmetic can seem appealing. There's a widespread assumption (gently let go here) that the active ingredient is what matters, and that the branded version is just packaging. In reality, what you're paying for in a licensed medicine includes manufacturing to pharmaceutical-grade sterility standards, independent quality testing, a precise and verified dose in every injection, stability data across the product's shelf life, and a pharmacovigilance system that tracks safety in the real world. A powder in a vial has none of those assurances attached to it.

If the cost of licensed treatment is the sticking point, the Wegovy price comparison page sets out what private providers typically charge and what a transparent price should include, which is a more useful comparison than weighing a licensed pen against an unverified powder.

What "self-mixing" involves and where it goes wrong

The process described in online guides typically involves reconstituting lyophilised (freeze-dried) peptide powder with bacteriostatic water, drawing the solution into a syringe, and injecting subcutaneously. Each of those steps carries risk. Bacteriostatic water itself must be pharmaceutical grade and correctly stored. The powder's stated concentration may not match its actual content. Reconstitution changes stability; once mixed, the solution must be handled, stored and used within a narrow window. Without a laminar flow hood, sterile technique and laboratory verification, contamination is not a theoretical concern, it is probable over repeated doses. Our guide to self-mix semaglutide explains in detail why each stage of this process is far more hazardous in practice than online instructions suggest.

There is more on the specific hazards of home preparation at our page on whether making your own semaglutide is possible, and separately a detailed look at what semaglutide should not be mixed with even in clinical settings. Neither page makes reassuring reading for the home-mixing approach.

The regulatory picture in the UK

Semaglutide is a prescription-only medicine under the Human Medicines Regulations 2012. That status means it can only be legally supplied following a valid prescription from a registered prescriber. Unlicensed compounding of prescription medicines for individual patients does exist in UK pharmacy practice, but it is tightly governed, it requires a licensed specials manufacturer or a pharmacy operating under a Specials licence, with robust quality systems. Kitchen reconstitution has no legal standing in that framework.

The MHRA has issued clear public warnings about unsafe fake and unlicensed weight-loss products circulating online, and their Yellow Card scheme allows anyone to report suspected unsafe products or sellers. The NHS summarises what patients should expect from a licensed semaglutide product on the NHS semaglutide medicines page, it's a useful reference for understanding what a genuine, regulated product looks like.

If you'd like to understand how semaglutide works as a licensed treatment, the semaglutide overview covers the mechanism, the evidence and the licensed strengths in plain language.

What the licensed route actually looks like in practice

Wegovy, the licensed semaglutide injection for weight management, comes as a pre-filled pen. There is nothing to mix, measure or draw up. The dose is set, the needle is pre-attached, and the pen is ready to use after a brief review of the patient information leaflet. It is refrigerated between uses (stored like any other medicine) and injected once a week into the abdomen, thigh or upper arm.

Starting treatment through a regulated private pharmacy like nume means a qualified prescriber reviews your health information personally before any medicine is issued. Our clinical team, led by our Independent Prescriber, assesses every consultation on the same day it arrives. If treatment is clinically suitable, it is dispensed from our GPhC-registered pharmacy (registration 9012878, verifiable at the GPhC register) and delivered the next working day by DPD in plain packaging. The Wegovy treatment page has full details on the licensed pen, the dose schedule and what to expect. If you have questions before starting, the FAQs cover the most common ones, and the weight-loss treatment overview explains where Wegovy sits alongside other options.

For anyone seriously considering weight management treatment, a conversation with a prescriber is the right starting point. Speak to our prescribers through a free consultation, no obligation, and everything is reviewed the same day.