If you're trying to make sense of a weight loss injection cost comparison in the UK, the first surprise is how wide the gap is. The exact same Mounjaro pen costs £131 a month at the cheapest tracked pharmacy and £220 at the priciest — an £89 difference for an identical product. Wegovy shows the same pattern, and so does the newer Wegovy pill.
This guide breaks down what each licensed injection actually costs in 2026, where the money goes as you step up doses, and how to avoid overpaying. Every figure comes from our tracker of regulated UK providers, last checked 01 September 2026. This is price and information only, not medical advice — a prescriber decides whether any of these are suitable for you.
Key takeaway: The same medicine can cost up to £89 a month more at one UK provider than another, so the brand matters less than where you buy. Wegovy is the cheapest way in (starter months from around £79.99), Mounjaro is the dearest but delivers the most weight loss, and the Wegovy pill sits in between with no needles. Always compare the price at your maintenance dose, not just the starter month.
Weight-loss injection cost comparison: the three licensed options
Three MHRA-licensed choices dominate the UK market in 2026: Mounjaro (tirzepatide), Wegovy (semaglutide injection) and the needle-free Wegovy pill (oral semaglutide). They're priced very differently, partly because of demand and partly because Mounjaro tends to produce the largest average weight loss.
Here's how the cheapest starter and top doses stack up across our tracked providers.
| Mounjaro | Wegovy | Wegovy pill | |
|---|---|---|---|
| Cheapest starter month | £131.00 (2.5 mg) | £79.99 (0.25 mg) | £86.99 (1.5 mg) |
| Most expensive starter month | £220.00 | £164.00 | £154.00 |
| Price spread, identical pen | £89.00 | £84.01 | £67.01 |
| Cheapest top maintenance dose | £266.00 (15 mg) | from 2.4 mg tier | 25 mg tier |
| Standout on cost | Dearest, most weight loss | Cheapest entry point | No needles, mid-priced |
Prices are per 4 weeks among our tracked UK providers, last checked 01 September 2026. First-month promotional prices are excluded from these headline ranges. See the full live figures on our homepage price table.
Why the same injection costs so much more elsewhere
It's the same licensed pen from the same manufacturer wherever you buy it. The price difference comes down to the provider's margin, consultation model and included support — not the medicine. A £220 Mounjaro pen is not "stronger" than a £131 one.
Some larger high-street names (Boots Online Doctor at £179, Superdrug at £179, Numan at £219) charge a premium for brand familiarity, while several GPhC-registered online pharmacies sell the identical starter pen for around £131–£140. Paying more can be worth it if the service adds value — regular clinical reviews, easy dose changes, responsive support — but you should know what you're paying for.
Our full prices compared across UK providers article ranks every option in detail.
Mounjaro: dose-by-dose costs climb steeply
Mounjaro is the priciest option and the cost rises sharply as you titrate upward. The starter dose is cheap by design, but most people settle on a maintenance dose of 5, 10 or 15 mg — where the real monthly cost lives.
To give a sense of the range at the top dose, 15 mg runs from about £266 (Next Script, PillSphere, Medicine Marketplace) up to £359 (Voy, Numan). That's a near-£100 monthly gap on the same pen. If you expect to reach a higher dose, compare providers on that tier rather than the starter price, which can be misleading.
Mounjaro's higher cost buys the largest average weight loss: around 21–22% of body weight at 10–15 mg over 72 weeks in the SURMOUNT-1 trial, versus about 15% for semaglutide in STEP 1. Our efficacy comparison lays out the numbers.
Wegovy: the cheapest entry point
Wegovy's injection is the least expensive way to start, with a 0.25 mg starter month from £79.99 at Next Script. Because the dose builds gradually over months, early costs stay low, and even the top providers rarely exceed £164 at the starter tier.
The Wegovy pill — the UK's first needle-free GLP-1 — starts from £86.99 at the 1.5 mg dose. Availability is thinner than the injections, so shop around. For people who dislike needles, the small premium over the cheapest injection is often the point.
Not sure which medicine fits your goals and budget? Our 5-question framework and Mounjaro vs Wegovy comparison are good next reads.
First-month discounts and voucher codes
Many providers cut the first month to win new customers, then charge the standard rate afterwards. These offers are genuine but temporary, so factor in the ongoing price when you compare — a cheap first month followed by an expensive maintenance rate can cost more over a year.
Our recommended provider, The Weight Clinic, offers a first Mounjaro month at £125 (£160 ongoing) with £35 off your first order using code NEWME, a refund if the prescriber declines you, and monthly video reviews to check your progress and adjust your dose. Its Wegovy and Wegovy pill both start at £80 for the first month.
How to compare without overpaying
- Compare at your likely maintenance dose, not just the starter month.
- Add up the first year — starter promo plus ongoing price — before deciding.
- Check the provider is regulated: a GPhC-registered pharmacy or CQC-regulated clinic. Never buy from unregulated sellers or so-called "compounded" versions, which are not licensed in the UK and can be unsafe.
- Weigh the support, not just the price — clinical reviews and easy dose changes have real value.
If side effects appear, report them through the MHRA Yellow Card scheme. Common effects across this class include nausea, diarrhoea, constipation, vomiting and tiredness.
Ready to compare a regulated option? The Weight Clinic is our recommended provider: first Mounjaro month £125 (then £160), £35 off with code NEWME, a refund if the prescriber declines, and monthly video reviews.
Frequently asked questions
Which weight-loss injection is cheapest in the UK?
Wegovy has the lowest entry point, with a 0.25 mg starter month from around £79.99. Mounjaro starts from about £131 and the Wegovy pill from about £86.99. Ongoing costs rise as you increase the dose, so compare at your likely maintenance level.
Why does the same pen cost so much more at some providers?
It's the identical licensed medicine wherever you buy it. The difference reflects each provider's margin, consultation model and included support — not the pen itself. Mounjaro ranges from £131 to £220 a month for the same starter dose.
Do first-month discounts make a provider cheaper overall?
Not always. Some providers cut the first month but charge a higher ongoing rate. Add up the starter promo plus the standard price over several months to see the true cost before committing.
Is it safe to buy the cheapest one I can find?
Only if it's from a GPhC-registered pharmacy or CQC-regulated clinic. Avoid unregulated sellers and "compounded" versions, which are not licensed in the UK. A prescriber must confirm the medicine is suitable for you.
Does paying more get you better results?
No — the medicine is the same at any price. A higher fee may buy more support, such as regular clinical reviews and easier dose adjustments, but it doesn't change how well the drug works.
Can I get these on the NHS instead?
Mounjaro is being rolled out on the NHS in phases from 2025, prioritising those with the highest BMI and most weight-related conditions first, so access still varies by area. Many people use private providers in the meantime.