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UK guide, checked 14 October 2026

Switching from Wegovy to Mounjaro in the UK

Thinking of moving from Wegovy to Mounjaro? This page sets out the UK doses, how long people usually wait after the last Wegovy pen, which Mounjaro dose you start on and what to send the pharmacy. Your prescriber makes the final call on all of it.

See how a switch works Check Mounjaro prices
Primary sources first eMC, MHRA, NHS and NICE
Independent information Monj does not prescribe, sell or dispense medicine
Last checked
October 2026

Checked 14 October 2026: Mounjaro KwikPen comes in 2.5, 5, 7.5, 10, 12.5 and 15 mg weekly doses. Wegovy injection steps are 0.25, 0.5, 1, 1.7 and 2.4 mg, with 7.2 mg licensed for some adults with obesity. Wegovy tablets come in 1.5, 4, 9 and 25 mg daily strengths.

Your reason matters

Why people switch

Your reason shapes the plan. Tell the prescriber which of these fits you.

Weight loss has stalled

The prescriber will check your current dose, how long you have been on it, missed doses and your injection technique. A plateau after 6 to 12 months is common on any of these medicines.

Side effects are hard to live with

Mounjaro is not gentler by default. Both medicines cause nausea, diarrhoea and constipation, mostly while the dose goes up. Some people do better on one than the other. Nobody can tell you which in advance.

Price or supply

Price is the main reason most people switch, and a lower price saves you money every month you stay on treatment. Before each reorder, see what other pharmacies are offering. Prices and discount codes change every few weeks, and your current pharmacy will rarely tell you when a rival is cheaper. Compare the full monthly price at your dose, with delivery, rather than the first-month deal alone. Our Mounjaro discount price list shows current pharmacy prices by dose.

The three options

Wegovy injection, Wegovy pill or Mounjaro

Wegovy injection and Wegovy tablets both contain semaglutide, a GLP-1 medicine. Mounjaro contains tirzepatide, which acts on both GIP and GLP-1 receptors. Each has its own dose ladder.

Wegovy injection

  • Semaglutide, once weekly
  • 0.25, 0.5, 1 and 1.7 mg, four weeks each
  • Usual maintenance dose 2.4 mg
  • 7.2 mg for some adults with obesity

Use iGovy for current UK Wegovy injection prices and provider checks.

Wegovy pill

  • Semaglutide, once daily
  • 1.5, 4, 9 and 25 mg steps
  • At least one month on each step
  • Taken after an overnight fast, then 30 minutes before food

Use Ogovy for current UK Wegovy pill prices, availability and pharmacy checks.

Mounjaro

  • Tirzepatide, once weekly KwikPen
  • Starts at 2.5 mg for four weeks
  • Then 5, 7.5, 10, 12.5 and 15 mg
  • Each rise after at least four weeks

Use Monj for current UK Mounjaro prices, provider policies and pharmacy checks.

Milligram numbers do not compare across these medicines. Tirzepatide is a different molecule, so Mounjaro's numbers run higher than Wegovy's. The Wegovy pill is absorbed less reliably than the pen. The UK leaflet says the 25 mg daily tablet gives average exposure close to the 2.4 mg weekly injection.

Clinical evidence

What the main trials found

These are group averages from separate trials with different people, doses and lengths. Use them as background, not as a ranking or a forecast for you.

Results by treatment and dose

Swipe sideways to see every column.

Headline trial results for adults without type 2 diabetes. Every group also had diet and activity support.
Treatment and trial Study Average weight change How to read the figure
Wegovy injection 2.4 mg STEP 1 1,961 adults, 68 weeks 14.9% reduction
Placebo: 2.4%		 Counts everyone, including people who stopped treatment.
Wegovy injection 7.2 mg STEP UP 1,407 adults, 72 weeks 18.7% reduction
2.4 mg: 15.6%
Placebo: 3.9%		 Studied in adults with obesity. Not the standard dose for everyone.
Wegovy pill 25 mg OASIS 4 307 adults, 64 weeks 13.6% reduction
Placebo: 2.2%		 Counts everyone. Among people who kept taking the pill, the figure was 16.6% against 2.8%.
Mounjaro injection 15 mg SURMOUNT-1 2,539 adults, 72 weeks 22.5% reduction
Placebo: 2.4%		 Based on people who stayed on their assigned treatment for the full study.

SURMOUNT-5 tested the two side by side

Over 72 weeks, adults with obesity and no diabetes took the highest dose they could tolerate of Mounjaro or Wegovy injection. Weight fell further on Mounjaro on average.

The trial used Mounjaro 10 or 15 mg and Wegovy 1.7 or 2.4 mg. It did not test Wegovy 7.2 mg or the Wegovy pill.

20.2%Mounjaro average reduction
13.7%Wegovy average reduction
Open the GLP Med Compare Tool

The tool lists trial results, dose context and UK approval status. It does not predict your own weight loss.

Planning the switch

How a Wegovy to Mounjaro switch works

Your prescriber sets the plan. Most UK switches follow these four steps.

Give the exact details of your Wegovy use

The prescriber needs the product, your current dose, the date of your last pen or tablet, how long you have used Wegovy and any missed doses. A photo of the pen or dispensing label settles most questions.

Follow your pharmacy's timing for the first dose

Your new pharmacy sets the timing, so follow its instructions. Many tell you to take your first Mounjaro dose on the day your next Wegovy dose would have fallen. Others ask you to wait longer, sometimes 28 days, and then start again from the lowest dose. Semaglutide has a half-life of about one week, so some is still in your body when you switch. Never take both in the same week.

Agree the Mounjaro starting dose

The Mounjaro licence starts everyone at 2.5 mg weekly for four weeks, then 5 mg. No official chart converts a Wegovy dose into a Mounjaro dose. Some prescribers start people coming off a high Wegovy dose on a higher Mounjaro step. That is a clinical judgement made for you, outside the standard licensed plan.

Stay on a dose or move up

Once you are on Mounjaro, you can stay on a dose that works or step up by 2.5 mg after at least four weeks. You make that choice with your prescriber. The maximum is 15 mg weekly. If you have missed doses recently, expect the prescriber to hold you at your current dose or drop you a step before you go higher.

Missed doses change the plan

If you missed two or more Wegovy doses before switching, say so. Your body may have lost some tolerance, and a higher Mounjaro start is more likely to make you sick. On Mounjaro, take a missed dose within 4 days. After 4 days, skip it and take the next one on your usual day. Keep at least 3 days between two doses.

Week by week

A typical switching timeline

Here is how a standard switch plays out when your prescriber starts you at 2.5 mg. Your dates may differ.

Week 0: last Wegovy dose

Take your final Wegovy pen as normal. Send a photo of the prescription label on your box to the new pharmacy now, so the consultation is done before your next dose is due.

Week 1: first Mounjaro dose

Take Mounjaro 2.5 mg, or the dose your prescriber chose, on your usual injection day. Inject into the stomach, thigh or upper arm. Mild nausea in the first two or three days is common.

Weeks 2 to 4: settle in

Keep to the same day each week. Eat smaller meals and drink enough fluid. Note any side effects to mention at your review.

Week 5: first review

Most people move to 5 mg here. If 2.5 mg was hard going, ask to stay on it for longer. If you take the contraceptive pill, add a barrier method such as condoms for 4 weeks after starting and 4 weeks after each dose rise, because Mounjaro can make the pill less reliable.

Week 9 onward: stay or step up

Review every four weeks. You can stay on a dose or move up by 2.5 mg with your prescriber's agreement.

The consultation

What to send the new pharmacy

Online pharmacies check you are already on treatment before they prescribe above the starting dose. Good evidence speeds this up.

  • A clear photo of the prescription label stuck to your Wegovy box, showing your name, the dose and the pharmacy
  • Some pharmacies also ask for a screenshot of your last Wegovy order showing the pharmacy, date and dose
  • The date of your last injection
  • Your starting weight and current weight, with dates
  • Any missed doses in the last two months
  • Side effects you had on Wegovy and how bad they were
  • Your other medicines, especially insulin, sulfonylureas or the contraceptive pill
  • Your reason for switching

Answer the consultation form honestly. A wrong answer can put you on a dose that makes you ill.

Cost check

Check the price before you switch

UK Mounjaro prices rise with the dose, and the gap between pharmacies can be large. Price these three things first.

Your first month

Usually the 2.5 mg pen, or the step your prescriber chose. Many pharmacies discount this one.

Your likely maintenance dose

Many people settle on 5 mg to 10 mg. Price the pen you expect to stay on for months.

Delivery and consultation fees

Some pharmacies add these on top. A cheap pen with a delivery charge every month can cost more over a year.

See the Mounjaro discount price list
Wegovy and Mounjaro treatment switch guide

If needles are the problem

The Wegovy pill and Foundayo are other options

The UK Wegovy tablet leaflet covers one switch: from the 2.4 mg weekly injection to the 25 mg daily tablet, starting one week after the last injection, if your prescriber agrees.

That rule does not apply to other Wegovy doses or to Mounjaro. The tablet also needs a strict morning routine. Fast for at least eight hours, swallow the tablet whole with up to 120 ml of water, then wait 30 minutes before food, drink or other tablets.

Foundayo (orforglipron) is a second daily pill. The MHRA approved it on 10 August 2026. You can take it at any time of day, with no fasting or water rules. Neither pill is on the NHS for weight loss at present, so you pay privately.

Weight loss on the pills is lower than on Mounjaro. In trials, the Wegovy pill 25 mg gave about 13.6% average weight loss over 64 weeks. Foundayo gave about 11.2% at the top 36 mg dose over 72 weeks. Mounjaro gave 20.2% in SURMOUNT-5 and 22.5% at 15 mg in SURMOUNT-1. If you mainly want the biggest result, an injection is the stronger choice. If you want to stop injecting, a pill may still suit you.

See current Wegovy pill information and UK provider prices on Ogovy. Compare Foundayo prices and discount codes on Dayo.

What to watch for

Side effects after you switch

Nausea, diarrhoea, vomiting, constipation and stomach pain are common with both medicines. They tend to peak in the first few days after a new dose and ease over the following weeks. Some people find the first Mounjaro weeks easier than their last Wegovy weeks. Others find them harder.

Tell the new prescriber about

  • Any current nausea, vomiting, diarrhoea or constipation
  • Past pancreatitis, gallbladder problems or severe gut disease
  • Diabetes medicines, especially insulin or sulfonylureas
  • Diabetic eye disease or any sudden change in vision
  • Pregnancy, breastfeeding or plans to get pregnant
  • Planned surgery, sedation or a general anaesthetic

Get urgent medical help for

  • Severe stomach pain that will not go away, especially if it spreads to your back
  • Repeated vomiting or signs of dehydration
  • A severe allergic reaction or trouble breathing
  • Sudden loss of vision, even partial

Report a suspected side effect to a clinician and through the MHRA Yellow Card scheme. Call 999 in an emergency.

Before you change

Questions to ask your prescriber

  • Why is Mounjaro a better fit for me than staying on Wegovy or trying the pill?
  • On what date should I take my first Mounjaro dose?
  • Which Mounjaro dose will I start on, and why?
  • What should I do if I still feel sick on the planned start date?
  • Can I stay on a dose if it works, or do you expect me to move up?
  • Does this affect my other medicines or my contraception?

Moving the other way? Read our guide to switching to Wegovy from Mounjaro.

Independent comparison

Compare prices for each treatment

Prices and pharmacy policies change often. Each of these sites covers one format, so you can check doses and offers side by side.

Weekly tirzepatide
Monj

Mounjaro prices, provider policies, maintenance information and UK pharmacy options.

Compare Mounjaro on Monj
Weekly semaglutide
iGovy

Wegovy injection prices, including the current dose range, discounts and provider checks.

Compare Wegovy injections on iGovy
Daily semaglutide
Ogovy

Wegovy pill prices, dose information, availability notes and provider checks.

Compare Wegovy pills on Ogovy
Daily orforglipron
Dayo

Foundayo pill prices, dose information and UK pharmacy discount codes.

Compare Foundayo on Dayo

Sources

How we checked this guide

We checked doses and switching advice against UK product information on eMC, MHRA and NHS pages and NICE guidance, then checked trial figures against the published papers. Last checked on 14 October 2026. Monj is not a pharmacy and does not recommend a treatment.

Plain answers

Frequently asked questions

Can I switch straight from Wegovy to Mounjaro?

Yes, with a prescriber's agreement. Follow your new pharmacy's instructions on when to start. Many say one week after the last Wegovy dose, on your usual injection day. Never take both in the same week.

How long should I wait after my last Wegovy injection?

Follow the timing your new pharmacy gives you. Many start you one week later, on the day your next Wegovy dose would have been due. Some ask you to wait 28 days and restart at 2.5 mg. The UK product information sets no fixed washout period.

What Mounjaro dose do I start on after Wegovy?

The licensed start is 2.5 mg weekly for four weeks. No official chart converts Wegovy doses to Mounjaro doses. Some prescribers start people coming off a high Wegovy dose on a higher step. Follow the dose your prescriber gives you.

Do I have to keep moving up the doses?

No. You can stay on a dose that works or move up by 2.5 mg after at least four weeks. Decide with your prescriber. If you have missed doses, expect to stay put or drop a step first.

What evidence will the pharmacy ask for?

Most UK online pharmacies ask for a clear photo of the prescription label stuck to your box, showing your name, the dose and the pharmacy. Some also ask for a screenshot of your last order. Have the date of your last injection ready too.

Is Mounjaro proven to work better than Wegovy?

In SURMOUNT-5, people on Mounjaro lost more weight on average than people on Wegovy injection. The trial did not test Wegovy 7.2 mg or the pill, and an average cannot tell you how you will respond.

Could I use the Wegovy pill instead of changing to Mounjaro?

Ask about it if the injection itself is the problem. The pill contains semaglutide and needs strict fasting each morning. Only the 2.4 mg injection has a set switch to the 25 mg tablet in the UK leaflet.

Will Mounjaro cause fewer side effects?

There is no guarantee. Both cause stomach and gut side effects, mostly after a dose rise. Tell the prescriber how you got on with Wegovy before you agree a plan.

Important: This guide is general information for UK readers. It is not medical advice or a recommendation to start, stop or switch treatment. A qualified prescriber who knows your medical history must decide whether a switch suits you, when to make it and which dose to use. NHS access rules differ from the wider licence and change during the phased rollout.

Monj does not prescribe, sell or dispense medicines. Trial averages do not predict your own result. If you think you have a serious side effect, seek medical help and report it through the MHRA Yellow Card scheme.

Sources referenced on this page

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