Off-Brand Weight Loss Injections: Understanding What's Licensed and What Isn't

Why there are no approved off-brand alternatives in this category

Generic medicines exist across many treatment areas because, once a patent expires, other manufacturers can produce the same molecule to the same standard and seek regulatory approval. That process has not happened with tirzepatide or semaglutide for weight management. Both are still under patent, and no generic version has been assessed or approved by the MHRA for weight loss use in the UK.

This is not a technicality. MHRA approval covers far more than the active ingredient. The pre-filled pen, the needle mechanism, the concentration per dose, the excipients in the formulation, and the manufacturing controls are all part of what gets reviewed. When someone offers you an "equivalent" product in different packaging or under a different name, none of those elements has been independently verified for safety or consistency. The NHS patient information for tirzepatide makes clear that Mounjaro is the licensed UK brand, not a category of products.

Some sellers market compounded or imported versions of semaglutide or tirzepatide. Compounded medicines are mixed outside the regulated manufacturing chain and are not equivalent to the licensed product, even if the active ingredient is nominally the same. They have not been assessed for the same standards of sterility, potency, or dose accuracy. That is a meaningful gap, not a cosmetic one.

What the counterfeit market actually looks like right now

The MHRA's enforcement activity over the past two years gives a clear picture of the risk. In October 2025, investigators raided the first known UK site manufacturing counterfeit tirzepatide pens. Around the same period, roughly 20 million doses of illegally traded weight loss medicines, worth approximately £45 million, were seized from the UK supply chain. Earlier warnings had documented hospitalisations linked to fake pens containing insulin instead of the labelled medicine.

These are not rare edge cases caught at the border. Some of this product was being sold domestically through social media, messaging apps, and websites designed to look like legitimate pharmacies. The sellers are often sophisticated enough to replicate branding convincingly.

The clearest signal that something is off? A legitimate online pharmacy in the UK will always be registered with the General Pharmaceutical Council. You can check any pharmacy in under a minute by searching the GPhC's public register. If a seller is not on it, they cannot legally dispense prescription medicines in the UK, full stop. That check costs nothing and removes most of the risk.

A separate red flag worth knowing: sellers offering these medicines without a prescription or clinical assessment are operating illegally, regardless of what the product looks like or how it is described. Unusually low prices are often the first sign something is wrong, but convincing prices exist too, so the GPhC check matters regardless.

What you are actually choosing between

The decision most people are really facing is not branded versus unbranded. It is whether to access a licensed medicine through a regulated route or to try to save money through an unregulated one. Framed that way, the trade-off becomes clearer.

Licensed Mounjaro and Wegovy, dispensed by a GPhC-registered pharmacy following a genuine clinical assessment, come with a number of protections that an off-brand purchase does not: a prescriber who has reviewed your health history, a verified supply chain, a product that matches its label, and someone to contact if things go wrong. Our clinical team at nume reviews every consultation personally before anything is dispensed, a real prescriber, not an automated system, reads your answers the same day.

For a longer look at how weight loss injections work in practice, including what to expect at each stage, that page covers the full picture. And if you are thinking about whether to start treatment or have questions about stopping weight loss injections at some point, those are conversations worth having with a prescriber who knows your case.

The cost of treatment is a fair concern, and our treatment pricing page sets out exactly what is included in a single transparent price: consultation, prescription, dispensing, and free tracked delivery. There are no add-ons and no subscription. If you are weighing up which weight loss injection brands are available and how they compare, or want to understand why these medicines are only available as named brands rather than generics, both pages go into more detail. If you would like to talk through whether treatment is suitable for you, you can start your free consultation and a GPhC-registered prescriber will review your answers the same day.