Best weight-loss injections in the UK: 2026 comparison

Search for the best weight-loss injection in the UK and you'll find plenty of confident answers — many written before the market changed. In 2026 three licensed options are worth comparing: Mounjaro (tirzepatide), Wegovy (semaglutide) and, new this year, the needle-free Wegovy pill (oral semaglutide). Each is "best" at something different.

This guide puts all three side by side on the measures that separate them: trial weight loss, evidence base, fit with daily life, and monthly cost. Every price below comes from our tracker of 24 regulated UK providers, last checked 01 September 2026.

The 2026 field: three licensed options

Mounjaro (tirzepatide)

Mounjaro is the only dual-hormone option — a "twincretin" mimicking both GIP and GLP-1 gut hormones. It's a once-weekly injection, starting at 2.5 mg and stepping up to a maximum of 15 mg. In SURMOUNT-1, participants averaged 21.4% loss at 10 mg and 22.5% at 15 mg over 72 weeks, versus 2.4% on placebo.

Wegovy (semaglutide)

Wegovy is a GLP-1-only weekly injection and the most established dedicated weight-loss jab in the UK. In STEP 1, the 2.4 mg dose averaged about 15% body-weight loss over 68 weeks. Since January 2026 the MHRA has also approved a higher 7.2 mg dose for obesity (BMI 30+), now stocked by 8 of our 24 tracked providers.

Wegovy pill (oral semaglutide)

The newest arrival puts Wegovy's active ingredient in a daily tablet — the UK's first needle-free GLP-1. It's taken on an empty stomach with a 30-minute wait before eating, and the dose builds over roughly 12 weeks to the full 25 mg. Availability is thin: just 2 of our 24 tracked providers list it.

Head-to-head: the numbers that matter

"From" prices are the cheapest per 4 weeks among our 24 tracked UK providers, last checked 01 September 2026. The trials enrolled different populations over different durations, so cross-trial percentages are a guide, not a precise ranking.

Best for sheer weight loss: Mounjaro

If your only yardstick is kilograms lost, Mounjaro leads — and not narrowly. About 90% of participants on 15 mg lost at least 10% of their body weight, and in SURMOUNT-5, the head-to-head trial against Wegovy, tirzepatide came out ahead at roughly 20% average loss versus about 14%.

The trade-offs are cost and side effects. Mounjaro's cheapest starter month (£143.96) is nearly double Wegovy's, and its top dose is the dearest maintenance option on the market. Common side effects — nausea, diarrhoea, constipation, vomiting, tiredness — match the rest of the class; our side-effect comparison covers the differences.

Best for track record — and heart protection: Wegovy

Wegovy has been prescribed in the UK longer than any rival, so it carries the most trial data and real-world experience. It also holds one card Mounjaro can't yet match: in the SELECT trial it cut heart-attack and stroke risk in people with existing cardiovascular disease — the only weight-loss injection with that proof.

It's also the cheapest way in: a starter month costs from £88.96, the lowest of the three. If around 15% average loss meets your goal — and for many people it does — the case for paying more is weaker than the headlines suggest. For a feature-by-feature breakdown, see our guide to how Mounjaro, Wegovy and the rest differ.

Best if you'd rather skip needles: the Wegovy pill

For some people the deciding factor is never having to inject. In OASIS 4 the 25 mg tablet averaged about 13.6% body-weight loss over 64 weeks — around 16.6% among those who took it consistently — and roughly 30% of participants lost at least a fifth of their body weight.

The catch is discipline: a daily dose on an empty stomach with a 30-minute wait before breakfast, and about three months of dose steps to reach full strength. Supply is limited too, and with only two tracked providers there's little price competition. A starter month runs from £99, the 25 mg dose from £190.

What "best" costs in July 2026

Price is where care pays off fastest: the medicine is identical whatever you pay. Across our 24 tracked providers, a starter month of Wegovy spans £89 to £164 — an £84 spread for the same pen. Mounjaro's runs £145.99 to £229, and at Wegovy's 1 mg dose the gap hits £90 a month.

The number that matters is the ongoing dose, not the starter promo: Wegovy 2.4 mg from £174.99, Mounjaro 15 mg from £288.99, the pill's 25 mg from £190 per four weeks. Our full price comparison breaks this down dose by dose, and the live tables on our homepage are re-checked regularly — always confirm the current price on the provider's own site.

So which is the best weight-loss injection in the UK?

It depends on which "best" you mean:

• Most weight loss: Mounjaro, on every trial measure to date.
• Most evidence and heart protection: Wegovy, with the longest UK record and the SELECT result.
• No needles: the Wegovy pill, if you can live with the morning routine.
• Tightest budget: compare maintenance-dose prices, not starter offers — the gap between providers is often bigger than the gap between drugs.

Two cautions. First, eligibility comes before preference: UK prescribers typically require a BMI of 30+, or 27+ with a weight-related condition, and the prescriber makes the final call. Second, these medicines carry side effects and none suits everyone. Still weighing it up? Our step-by-step framework for choosing a weight-loss injection walks through the decision in order.

Frequently asked questions

This article is price and product information, not medical advice. Talk to your GP or pharmacist before starting any weight-loss medicine, and report suspected side effects via the MHRA Yellow Card scheme.