Lilly and semaglutide: what's the connection, and what does Eli Lilly actually make?

Step 1: Understanding who makes what (and why the confusion starts)

The names Eli Lilly and Novo Nordisk come up constantly in the same conversations, news articles and pharmacy searches, which is where the mix-up begins. Both companies produce injectable medicines used in weight management. Both are multinational pharmaceutical manufacturers with a long history in metabolic medicine. That's where the similarity ends.

Novo Nordisk developed and holds the licence for semaglutide. In the UK, the weight-management version is branded Wegovy and the diabetes version is Ozempic. If you want to understand more about the other side of this comparison, you can read about Eli Lilly's position on semaglutide and how it differs from their licensed tirzepatide product. The two medicines are related in the sense that both activate GLP-1 receptors, which slow gastric emptying and reduce appetite, but tirzepatide also activates the GIP receptor, making it, in pharmacological terms, a different class of drug. A question our prescribers hear most weeks is whether you can just swap between the two; the short answer is no, because they are distinct molecules prescribed through individual clinical assessments.

Knowing this distinction is also useful when checking a pharmacy's supply chain. Medicines sourced through the licensed UK supply chain should arrive from the original manufacturer. If a seller cannot confirm manufacturer provenance, that is a significant concern for a prescription-only medicine like either of these.

Step 2: What semaglutide (Wegovy) does and how the UK licence works

Semaglutide acts on GLP-1 receptors in the gut and brain, reducing hunger signals and slowing the rate at which the stomach empties. Novo Nordisk's Wegovy injection is licensed in the UK for adults with a BMI of 30 or above, or 27 and above where a weight-related health condition is present. The standard dose pathway starts low and increases gradually over several months, with 2.4mg as the established maintenance dose. In January 2026 the MHRA approved a higher 7.2mg maintenance dose, and a dedicated single-dose pen for that strength followed in April 2026, approved for adults with a BMI of 30 or higher.

Trial data published in the STEP 1 study in the New England Journal of Medicine reported an average body-weight reduction of around 15% over 68 weeks at the 2.4mg dose, alongside a reduced-calorie diet and increased physical activity. The 7.2mg data from subsequent trials reported approximately 20.7% average weight loss over 72 weeks, narrowing the gap with the results seen in tirzepatide trials.

It is worth being precise about what Ozempic is here: also semaglutide, but at lower doses and licensed specifically for type 2 diabetes. The MHRA is clear that Ozempic is not a weight-loss medicine; prescribing it for weight management is off-label and not the route a regulated UK pharmacy would take. You can read more about how the licensed doses compare and what that means for treatment planning.

Step 3: How tirzepatide (Eli Lilly's medicine) sits alongside semaglutide

Tirzepatide, Eli Lilly's contribution to this space, received its UK licence for weight management and type 2 diabetes. It works on both the GIP and GLP-1 receptors, which is why it is sometimes called a dual agonist. The SURMOUNT-1 trial reported average weight reductions of around 20–21% at the highest dose over 72 weeks, and the SURMOUNT-5 head-to-head trial, published in the New England Journal of Medicine in 2025, found greater average weight loss with tirzepatide compared with semaglutide at the 2.4mg weekly dose that forms the basis of most licensed treatment plans over the same period.

Those trial numbers do not make one medicine automatically right for a given person. Tolerability, existing health conditions, medication interactions, and individual response all feed into the prescriber's decision. That is precisely why both medicines sit behind a prescription. You can explore the clinical profile of semaglutide in more detail if you want to take those comparisons further before speaking to a prescriber.

If you're thinking about cost alongside effectiveness, our weight-loss treatment overview sets out how private treatment is structured in the UK and what a single transparent price covers, without subscriptions or hidden fees.

Step 4: Getting either medicine legally and safely in the UK

Both semaglutide (Wegovy) and tirzepatide (Mounjaro) are prescription-only medicines. The only lawful route to either of them is a prescription issued by a qualified prescriber following a clinical assessment of your circumstances. Neither can be legally sold without that step, regardless of what some online listings might suggest.

The MHRA has warned repeatedly about counterfeit injectable weight-loss pens circulating through social media and unverified online sellers, some containing no active ingredient, others containing substances dangerous to inject. Verifying that a pharmacy is registered with the GPhC before placing any order is the single most important safety check you can make; the GPhC pharmacy register is publicly searchable and takes about thirty seconds to use. If a price looks far below the market range, or if a seller cannot show a GPhC registration, step away.

At nume, every consultation is reviewed personally by a GPhC-registered Independent Prescriber, the same day you submit it, assuming you order before noon Monday to Friday. Identity is verified, weight is confirmed on video, and treatment is dispatched in plain, unbranded packaging via tracked next-working-day DPD delivery. Find out whether you're clinically suitable by starting a free consultation with our prescribers.