Comparisons · 7 March 2026 · 10 min read

Wegovy vs Mounjaro — Which Weight Loss Injection Is Right for You? (UK 2026)

Both are weekly injections. Both are genuinely effective. But they're not the same — choosing the right one could make a real difference to your results, side effects, and bank balance.

Last updated: March 2026 | 10 min read

So you've decided to try a weight loss injection — brilliant. But now you're faced with the big question everyone's asking right now: Wegovy or Mounjaro?

Both are weekly injections. Both are genuinely effective. Both are available privately in the UK. But they're not the same — and choosing the right one could make a real difference to your results, your side effects, and your bank balance.

Here's everything you need to know, in plain English.

The Quick Answer

• Mounjaro has historically produced slightly better weight loss results — but it got a lot more expensive in late 2025
• Wegovy is now more affordable, and a new higher dose approved in January 2026 means the results gap has almost closed
• For most people in the UK right now, Wegovy is the better starting point — especially if cost is a factor

But let's dig into the details so you can make the right call for you.

What's the Difference Between Them?

Wegovy contains semaglutide — a drug that mimics a hormone called GLP-1, which tells your brain you're full. It slows digestion and reduces appetite, so you naturally eat less.

Mounjaro contains tirzepatide — which does the same thing as Wegovy, but also mimics a second hormone called GIP. So it works on two appetite pathways instead of one, which is why it tends to produce slightly stronger results.

Think of it like this: Wegovy is a one-engine plane. Mounjaro is a two-engine plane. Both fly — one just has a bit more power.

How Do the Results Compare?

This is what everyone wants to know. Here's the honest picture based on clinical trials:

The big news for 2026 is that Wegovy now has a higher 7.2mg dose, approved by the UK's MHRA in January 2026. At that dose, average weight loss is around 20.7% — almost identical to Mounjaro. The gap that used to exist has almost completely closed.

Real talk: These are averages from clinical trials. Your results will depend on your starting weight, diet, exercise, and how your body responds. Some people do brilliantly on Wegovy; others find Mounjaro more effective for them personally. There's no one-size-fits-all answer.

What About Side Effects?

Both medications have similar side effects — mostly digestive, and mostly in the early weeks as your body adjusts to the medication.

Most common for both:

• Nausea (especially in the first few weeks)
• Constipation or diarrhoea
• Feeling full very quickly
• Occasional fatigue

How they differ:

• Mounjaro users sometimes report slightly more nausea initially, possibly because it works on two hormone pathways
• Wegovy users sometimes report fatigue, particularly in the early stages
• Both improve significantly after the first 4–8 weeks as your body adapts

Around 6% of Mounjaro users and 8% of Wegovy users stop treatment due to side effects — so the vast majority of people tolerate both well.

Tip: Starting on the lowest dose and increasing slowly (which is how both drugs work anyway) makes side effects much more manageable. Don't rush the dose increases.

How Much Do They Cost in the UK?

This is where things have changed significantly. In September 2025, Eli Lilly raised Mounjaro's UK prices dramatically — in some cases by up to 170%.

Here's roughly what you're looking at now from private UK clinics:

Wegovy is now meaningfully cheaper at higher doses — and with the new 7.2mg dose delivering similar results to Mounjaro, the value case for Wegovy is stronger than it's ever been.

Which UK Clinics Can I Use?

Both medications are prescription-only — you can't just buy them online without a proper medical assessment. Here are some reputable UK options:

For Wegovy:

• Superdrug Online Doctor — one of the most affordable and straightforward UK options
• Manual — popular telehealth service, good support
• Voy by Oviva — includes dietitian support alongside medication

For Mounjaro:

• Superdrug Online Doctor — also offers Mounjaro
• Manual — offers both
• Your local private GP or weight loss clinic — worth checking as prices vary

Does the NHS Cover Either of Them?

The short answer is: sometimes, for some people, but don't count on it.

Both Wegovy and Mounjaro are available through NHS specialist weight management services — but access is extremely limited and waiting lists are long. You typically need a BMI of 35+ with a related health condition, or 40+ without one, to be considered.

For most people, private prescription is the realistic route right now. NHS coverage is expected to expand over the coming years as the health system recognises the long-term cost savings of treating obesity.

Important Things to Know Before You Start

Depending on what other medications you take, there are some specific things worth flagging before you begin either injection.

On the Contraceptive Pill?

If you're taking an oral contraceptive pill and you start Mounjaro, you need to know this: Mounjaro can affect how well your body absorbs the pill, because it slows stomach emptying and changes how quickly oral medications pass through your gut. This means the pill may be less effective at preventing pregnancy.

Current guidance is to use additional contraception (such as condoms) for at least four weeks after starting Mounjaro, and for four weeks after any dose increase. Speak to your prescriber about this before you start — they should be raising it with you, but not everyone does.

Wegovy has a similar but less pronounced effect. It's still worth discussing with your prescriber if you're on the pill.

On HRT?

If you're taking HRT tablets (oral hormone replacement therapy), Mounjaro may affect how well they're absorbed — for the same reason as the pill. Patches or gels are recommended instead of tablets as they absorb directly through the skin and aren't affected by changes in gut motility.

If you're already on HRT tablets and starting a GLP-1 medication, raise this with your prescriber. Switching to a patch or gel version of your HRT is often a straightforward change and removes the absorption concern entirely.

On Levothyroxine (Underactive Thyroid)?

GLP-1 medications slow down how quickly your stomach empties, which can delay the absorption of levothyroxine — a medication that's highly sensitive to timing and absorption conditions.

If you take levothyroxine, your prescriber may recommend taking it at least 30–60 minutes before food (and any other medication), and they may want to monitor your thyroid function more closely during the first few months on a GLP-1. If you notice symptoms of under-treated thyroid (fatigue, feeling cold, weight plateau), ask for a blood test to check your levels.

Wegovy vs Mounjaro — Which Should YOU Choose?

Here's a simple guide:

Choose Wegovy if:

• Cost is important to you — it's significantly cheaper at higher doses now
• You want the medication with the longest safety track record
• You have cardiovascular risk factors — Wegovy is the only one currently approved to reduce heart attack and stroke risk
• You're just starting out and want to try the most established option first

Choose Mounjaro if:

• You've tried Wegovy and not seen the results you wanted
• Budget is less of a concern and you want the historically stronger results
• Your doctor recommends it based on your specific health profile
• You have type 2 diabetes (Mounjaro has strong evidence for blood sugar control too)

Frequently Asked Questions

Can I switch from Wegovy to Mounjaro (or vice versa)?
Yes — but you should wait at least 7 days between your last dose of one and starting the other. Always do this under the guidance of your prescribing clinician.

Which one works faster?
Both start reducing appetite within the first week or two. Most people see noticeable weight loss by weeks 4–8. Mounjaro may produce faster early results for some people, but individual responses vary a lot.

What happens if I stop taking them?
This is important to know before you start. Research published in the British Medical Journal in early 2026 found that people who stop GLP-1 medications regain weight significantly faster than those who stop conventional dieting. The medication manages the condition — it doesn't cure it. Most people need to continue long-term or make substantial lifestyle changes to maintain their results.

Is Ozempic the same as Wegovy?
They both contain semaglutide, but Ozempic is licensed for type 2 diabetes in the UK, not weight loss. Wegovy is the weight loss version. Ozempic is not officially prescribed for weight loss in the UK.

Will my GP prescribe these?
Some GPs will refer you to specialist services, but most people in the UK access these medications privately. Online clinics like Superdrug Online Doctor and Manual make the process straightforward.

The Bottom Line

In 2026, Wegovy and Mounjaro are more evenly matched than ever thanks to Wegovy's new higher dose. For most people in the UK starting their weight loss injection journey, Wegovy is the sensible first choice — it's more affordable, has the longest safety record, and now delivers results that are very close to Mounjaro.

If cost isn't a concern and you want every possible advantage, or if you've plateaued on Wegovy, Mounjaro is worth considering.

Either way — both are genuinely life-changing for the right person. The best injection is the one you can afford to stay on long enough to see real results.

Disclaimer: This article contains affiliate links. We may earn a small commission if you sign up through our links, at no extra cost to you. This is not medical advice — always consult a qualified healthcare professional before starting any prescription medication.