How Wegovy's competitors compare — and what that means for you

What separates these medicines at the mechanism level

Wegovy (semaglutide injection) works by mimicking GLP-1, a gut hormone released after eating. It slows stomach emptying, signals fullness to the brain and reduces appetite. Mounjaro (tirzepatide) takes a different approach: it activates both the GLP-1 receptor and the GIP receptor simultaneously. GIP is a second gut hormone that amplifies the appetite-suppression signal and appears to influence how the body handles energy. That dual action is why Mounjaro is described by the NHS as a dual receptor agonist, and it is the only weight-loss medicine licensed in the UK with that mechanism.

The Wegovy tablet, approved by the MHRA on 11 June 2026 as the first oral GLP-1 medicine licensed for weight management in the UK, uses the same active ingredient as the Wegovy injection but pairs it with an absorption enhancer called SNAC so it can be taken by mouth. It is taken once daily rather than once weekly. The mechanism is identical to the injection; the formulation is the practical difference.

Saxenda (liraglutide) is an older GLP-1 injection licensed for weight management, but it requires a daily rather than weekly injection and its trial results are more modest. Orlistat, a lipase inhibitor, works entirely differently by blocking fat absorption in the gut rather than affecting appetite hormones. Neither Ozempic nor Rybelsus is licensed for weight loss, and both are semaglutide products used for type 2 diabetes, a distinction the NHS medicines page for semaglutide makes clearly.

What the trial evidence actually shows across the competing options

Choosing between these medicines is not straightforward from trial data alone, because the studies used different populations, different lengths and different comparators. With that caveat stated: in the STEP 1 trial (68 weeks, semaglutide 2.4 mg), participants lost an average of around 15% of body weight. In SURMOUNT-1 (72 weeks, tirzepatide 15 mg), average reduction reached roughly 20–21%. The OASIS 4 trial (64 weeks, oral semaglutide 25 mg) found approximately 13.6% average weight loss regardless of adherence, or around 17% among participants who stayed fully adherent throughout.

A direct head-to-head comparison does exist. The SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, compared tirzepatide against semaglutide 2.4 mg in adults with obesity and no diabetes over 72 weeks. Tirzepatide produced greater average weight reduction. NICE's appraisal of tirzepatide (TA1026) acknowledged this, noting that indirect comparisons favour tirzepatide. The higher 7.2 mg semaglutide dose, approved by the MHRA in January 2026, reported approximately 20.7% average weight loss in trials, which narrows the gap with tirzepatide 15 mg considerably.

A useful place to see these medicines laid out side by side is our detailed comparison of Wegovy and its alternatives, which covers how the trial populations, durations and results translate to what you might realistically expect.

Practical differences: injection, tablet, dose schedule, storage

For some people the route of administration matters as much as any percentage point. The Wegovy injection and Mounjaro are both once-weekly subcutaneous injections; Mounjaro comes as a KwikPen, each pen containing four weekly doses. The Wegovy tablet is taken once daily, first thing in the morning on an empty stomach with a small amount of plain water, with a wait of at least 30 minutes before food or other medicines. Crucially, it requires no refrigeration, a practical advantage for people who travel frequently or find cold-chain storage a burden.

Storage matters for the injections. Both Wegovy and Mounjaro should be refrigerated at 2–8°C; there is a limited window for room-temperature storage if needed, but the exact details are in the Patient Information Leaflet for each product and your prescriber will go through them with you. The tablet simplifies that entirely.

Cost is another real factor. The list price of Mounjaro rose significantly from September 2025, the highest dose pen now carries a list price of around £330 for a four-week supply, with private market prices broadly ranging from roughly £149 to £375 per month depending on dose and provider. If you are curious about the company behind Wegovy and how it approaches pricing, that context can be useful when comparing options. If you want a grounded picture of what private treatment realistically costs, our weight-loss treatment overview explains what legitimate pricing includes.

All three medicines share a broadly similar side-effect profile: nausea, vomiting, diarrhoea and constipation are the most commonly reported, typically most noticeable at the start of treatment or after a dose increase, and for many people they settle within a week or two. The MHRA issued a Drug Safety Update in January 2026 highlighting acute pancreatitis as a known but infrequent risk across GLP-1 medicines, persistent, severe stomach pain that may reach the back is a signal to seek urgent medical help. Any suspected side effect can be reported at the MHRA's Yellow Card scheme.

Which medicine is actually right for you, and how that gets decided

The honest answer is that no webpage can tell you. Your weight history, other health conditions, current medicines, and how you feel about weekly injections versus a daily tablet are all part of the conversation a prescriber needs to have with you. NICE recommends tirzepatide (TA1026) for adults with a BMI of 35 or above and at least one weight-related condition; its semaglutide recommendation (TA875) covers similar thresholds but restricts NHS use to a maximum of two years within a specialist weight management service. The oral tablet has no NICE appraisal yet.

Private prescribing follows the licensed criteria more directly: BMI of 30 or above, or 27 or above with a qualifying weight-related condition such as hypertension, type 2 diabetes or obstructive sleep apnoea. Understanding which drug company manufactures Wegovy and holds its licence can also help you make sense of how prescribing criteria are shaped and why they differ between products.

At nume, a GPhC-registered Independent Prescriber reads your consultation personally, not software, not an automated triage tool. If you order before midday, the review happens the same working day; once approved, your treatment leaves our pharmacy that afternoon, arriving the next working day via DPD in plain, unbranded packaging. You can see how that process works by reading about how online prescribers handle Wegovy and similar treatments, or find out more about the doctors who prescribe Wegovy and what their involvement in your care looks like. You can also learn more about who we are as a clinician-led service. When you are ready to talk through which option suits you, start your free consultation and a prescriber will take it from there.