GLP-1 Medications Compared UK: Mounjaro, Wegovy, the Pill & Foundayo

If you are trying to make sense of the different weight-management injections and tablets you have heard about, this is a plain-English look at the main GLP-1 medications compared for UK readers. Mounjaro, Wegovy, the newer Wegovy pill and Foundayo all belong to the same broad family, but they differ in how they are taken, how much weight people lose on average, and how you can access them.

This article is information only, not medical advice, and it does not recommend any product or supplier. Every one of these medicines is prescription-only in the UK, and whether any is suitable for you is a decision for a qualified prescriber.

GLP-1 medications compared: the quick overview

Before the detail, here is the shape of the landscape. Mounjaro and Wegovy are once-weekly injections; the Wegovy pill and Foundayo are daily tablets. Mounjaro produces the largest average weight loss in trials, followed by the Wegovy injection and then the Wegovy pill. For a side-by-side breakdown you can also visit our comparison page, and if you are new to the class, start with what GLP-1 medications are and how the class works.

Why they are similar

GLP-1 (glucagon-like peptide-1) is a hormone your gut releases after eating. These medicines switch on the same receptors, reducing appetite, slowing stomach emptying and helping control blood sugar. Because appetite falls, most people naturally eat less. Crucially, they are all designed to work alongside changes to diet and activity, not instead of them.

Why they differ

The differences come down to the active ingredient, how the medicine is delivered, and the doses studied in trials. One product (Mounjaro) also acts on a second hormone receptor, which is one reason it tends to produce larger average weight loss.

Mounjaro (tirzepatide)

Mounjaro is a once-weekly injection that acts on two receptors — GLP-1 and GIP. In the SURMOUNT-1 trial, adults with obesity or overweight (without type 2 diabetes) lost, on average, 16.0% of body weight at 5 mg, 21.4% at 10 mg and 22.5% at 15 mg over 72 weeks, versus 2.4% on placebo. About 90% of people on 15 mg lost at least 10% of their body weight.

Dosing is stepped up slowly: 2.5 mg weekly for 4 weeks as a starter (not a treatment dose), then 5 mg, rising in 2.5 mg steps after at least 4 weeks each, up to a maximum of 15 mg. Mounjaro is MHRA-licensed for weight management and recommended by NICE (TA1026, December 2024), with a phased NHS rollout from 2025 that started with those in greatest clinical need and widened in 2026/27. More detail is on our Mounjaro page.

Wegovy (semaglutide injection)

Wegovy is a once-weekly GLP-1 injection. In the STEP 1 trial, the 2.4 mg dose produced average weight loss of about 15% (mean −14.9%) over 68 weeks, versus about 2.4% on placebo, alongside lifestyle changes.

The dose is increased gradually over roughly 16 weeks — 0.25 mg, then 0.5, 1 and 1.7 mg — reaching the usual 2.4 mg maintenance dose from around week 17. Since January 2026 the MHRA has also approved a higher 7.2 mg weekly dose for obesity (BMI 30+). On the NHS in England, Wegovy is available only through specialist weight-management services (NICE TA875) for up to two years, with wider access privately. See our Wegovy page.

The Wegovy pill (oral semaglutide)

Approved by the MHRA on 11 June 2026, the Wegovy pill is the UK's first oral GLP-1 weight-loss medicine — a daily tablet rather than an injection. In the OASIS 4 trial, the 25 mg dose gave average weight loss of about 13.6% over 64 weeks (versus about 2.2% on placebo); among people who took it consistently the average was about 16.6%, and around 30% lost at least 20% of their body weight.

The tablet is stepped up too — 1.5 mg, then 4 mg, 9 mg and finally 25 mg, with at least a month at each level, so about three months to reach the full dose. It is currently available only via private prescription; NHS funding would need a separate NICE appraisal. Learn more on our Wegovy pill page.

Foundayo (orforglipron)

Foundayo is a once-daily small-molecule GLP-1 tablet from Eli Lilly, authorised by the MHRA on 10 August 2026 for weight management and for type 2 diabetes — the UK's second licensed GLP-1 pill, after the Wegovy pill. It comes in six strengths (0.8, 2.5, 5.5, 9, 14.5 and 17.2 mg), stepped up with at least a month at each level, and unlike oral semaglutide it can be taken at any time of day with or without food or water. In the ATTAIN-1 trial the highest research dose averaged about 12.4% weight loss over 72 weeks. It is currently available only on private prescription; NICE's appraisal is in progress, so it is not yet on the NHS. Full detail is on our dedicated Foundayo page — always check the current MHRA-approved information with a prescriber.

How the numbers compare — with a caveat

It is tempting to rank these medicines purely on trial weight-loss figures: Mounjaro (~21–22% at higher doses), the Wegovy injection (~15%), and the Wegovy pill (~13.6%). But those figures come from different trials, with different participants, durations and designs, so they are not a like-for-like head-to-head.

Average results also hide a wide range of individual outcomes. Some people respond strongly; others less so. The "best" medicine on paper is not automatically the right one for a particular person — tolerance of side effects, whether you prefer a weekly injection or a daily tablet, other health conditions and prescriber judgement all matter.

Injection versus tablet

A once-weekly injection means one small self-administered dose a week, which many people find convenient. A daily tablet avoids needles but has to be taken correctly — oral semaglutide is usually taken on an empty stomach with a small sip of water, waiting before eating or drinking. Neither format is universally "better"; it depends on your routine and preferences, which you can discuss with a prescriber.

Eligibility and access in the UK

For weight management, private eligibility usually starts at a BMI of 30 or above, or 27 or above with a weight-related condition such as high blood pressure, type 2 diabetes or sleep apnoea. NHS access is more restricted and varies by product and area.

A prescriber will check your full medical history. These medicines are not suitable for everyone — for example during pregnancy or breastfeeding, or where there is a history of certain pancreatic or thyroid conditions. Only a GPhC-registered pharmacy or CQC-regulated clinic prescriber can decide whether treatment is appropriate. On cost: private prices vary between regulated providers, so compare carefully — and be wary of anywhere offering unlicensed or "compounded" versions, which are not approved for use in the UK.

Side effects and safety across the class

The most common side effects are digestive: nausea, diarrhoea, constipation and vomiting, especially in the early weeks or after a dose increase. These often ease over time, which is why doses are raised slowly. Tiredness and headache are also reported.

Less commonly, more serious problems can occur, including pancreatitis (rare), gallstones and dehydration that can strain the kidneys. People also using insulin or a sulfonylurea may face a higher risk of low blood sugar. The Wegovy injection labelling also notes a rare eye condition (NAION). If you experience a side effect, you can report it through the MHRA Yellow Card scheme, and seek medical advice for anything severe or persistent.

For more general questions, see our FAQ page or return to the homepage.

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