UK guide updated for July 2026
Switching from Wegovy to Mounjaro
Wegovy is no longer just one weekly injection. There is now a daily Wegovy pill, plus the newer 7.2 mg injection dose for some adults with obesity. That makes the choice less obvious, so this guide looks at the current evidence, the practical differences and how a safe switch is actually planned.
Updated 22 July 2026: Wegovy tablets are approved in the UK in 1.5 mg, 4 mg, 9 mg and 25 mg strengths. Treatment is increased gradually, with at least one month at each dose. The tablet must be taken after an overnight fast, with no more than 120 ml of water, followed by a wait of at least 30 minutes before food, drink or other oral medicines.
Start with the real reason
What are you hoping a switch will fix?
It is easy to jump straight to the headline percentages. In practice, the best discussion starts with what is not working now.
Results have slowed or stopped
A prescriber may first look at dose, how long you have been on it, injection technique, tablet timing, other medicines and whether your expectations match the usual treatment curve.
Side effects are getting in the way
Mounjaro is not automatically gentler. Both treatments commonly cause gut side effects, especially while the dose is rising. A change may help, but it can also bring a new pattern of symptoms.
The format no longer suits you
If needles, travel or storage are the main issue, the daily Wegovy pill may be worth discussing before changing active ingredient. It has a stricter morning routine, so it is not the easier option for everyone.
The 2026 choice
Wegovy injection, Wegovy pill or Mounjaro?
Wegovy injection and Wegovy tablets both contain semaglutide. Mounjaro contains tirzepatide, which acts at GIP and GLP-1 receptors. The route and routine differ just as much as the name on the box.
Wegovy injection
- Semaglutide
- Once weekly
- Usual maintenance dose 2.4 mg
- 7.2 mg may be used for some adults with obesity if needed
Wegovy pill
- Semaglutide
- Once daily
- 1.5 mg, 4 mg, 9 mg and 25 mg dose steps
- Needs an overnight fast and a 30 minute wait after the dose
Mounjaro
- Tirzepatide
- Once weekly injection
- Licensed starting dose 2.5 mg
- Maintenance doses 5 mg, 10 mg and 15 mg
The pill is not simply the injection dose written in milligrams. Oral semaglutide has much more variable absorption. According to the UK product information, the 25 mg daily tablet produces average exposure comparable with the 2.4 mg weekly injection, but individual tablet absorption varies more widely.
Clinical evidence
What the main weight loss trials actually found
These are averages across study groups, not promises. Separate trials used different people, doses, designs and time periods. The figures are useful context, but they should not be treated as a simple ranking.
Results by treatment and dose
Swipe sideways to see every column.
| Treatment and trial | Study | Average weight change | How to read it |
|---|---|---|---|
| Wegovy injection 2.4 mg STEP 1 | 1,961 adults, 68 weeks | 14.9% reduction Placebo: 2.4% |
Treatment policy estimate, so it includes results regardless of stopping treatment or using other weight management approaches. |
| Wegovy injection 7.2 mg STEP UP | 1,407 adults, 72 weeks | 18.7% reduction 2.4 mg: 15.6% Placebo: 3.9% |
This higher dose was studied in adults with obesity. It is not the standard dose for everyone. |
| Wegovy pill 25 mg OASIS 4 | 307 adults, 64 weeks | 13.6% reduction Placebo: 2.2% |
Treatment policy estimate. If everyone had remained on treatment without other weight management therapy, the estimate was 16.6% versus 2.8%. |
| Mounjaro injection 15 mg SURMOUNT-1 | 2,539 adults, 72 weeks | 22.5% reduction Placebo: 2.4% |
Efficacy estimate, which asks what the result might look like if people stayed on their assigned treatment for the full study. |
The fairest direct comparison is SURMOUNT-5
In this 72 week head-to-head trial, adults with obesity but without diabetes received the maximum tolerated dose of Mounjaro or Wegovy injection. Average weight reduction was greater with tirzepatide at the doses studied.
Important limit: this trial compared Mounjaro 10 mg or 15 mg with Wegovy 1.7 mg or 2.4 mg. It did not test the 7.2 mg Wegovy injection or the Wegovy pill.
The tool shows direct trial results, dose context, UK approval status and clearly labelled estimates. It is an evidence guide, not a personal weight loss forecast.
Safe switching
How a Wegovy to Mounjaro switch is normally planned
The exact plan belongs to your prescriber. A sensible clinical review usually covers these four points.
Confirm what you are taking now
Your prescriber needs the exact product, dose, date of the last injection or tablet, how long you have used it and whether doses were missed. A photo of the box or dispensing label can help.
Review the reason for changing
Side effects, limited response, supply, cost and needle anxiety lead to different decisions. If symptoms are still active, a prescriber may want them to settle before another treatment starts.
Agree the last and first dose dates
There is no licensed dose conversion from Wegovy to Mounjaro. Semaglutide has a half-life of about one week and remains in the circulation for several weeks, so timing must be individual. Do not overlap the two or switch back and forth yourself.
Start low and review
The licensed Mounjaro starting dose is 2.5 mg once weekly, followed by 5 mg after four weeks. Any later rise is made in 2.5 mg steps after at least four weeks on the current dose, depending on response and tolerability.
There is no universal five week rule
The old version of this page told everyone to wait four to five weeks. That was too rigid. UK product information does not give one fixed Wegovy to Mounjaro washout period. A longer gap may be appropriate when side effects are ongoing or there are other clinical concerns, but the date should be set by the prescriber looking after you.
If needles are the problem
Changing format may be another option
The UK Wegovy tablet information includes one specific transition: someone using the 2.4 mg weekly Wegovy injection can move to the 25 mg daily tablet, starting one week after the last injection, if their prescriber considers it suitable.
That instruction does not create a general conversion chart. It does not cover a switch from 7.2 mg Wegovy, every lower injection dose or a move to Mounjaro. The tablet also needs a reliable routine: at least eight hours fasting, swallow it whole with no more than 120 ml of water, then wait at least 30 minutes before food, drink or other tablets.
See current Wegovy pill information and UK provider prices on Ogovy.
What to watch for
Side effects do not reset just because the brand changes
Nausea, diarrhoea, vomiting, constipation and stomach discomfort are common with both semaglutide and tirzepatide. They are often most noticeable while the dose is being increased.
Tell the new prescriber about
- Any current nausea, vomiting, diarrhoea or constipation
- Previous pancreatitis, gallbladder problems or severe digestive disease
- Diabetes treatment, especially insulin or sulfonylureas
- Diabetic eye disease or any sudden change in vision
- Pregnancy, breastfeeding or plans for pregnancy
- Planned surgery, sedation or a general anaesthetic
Get urgent medical help for
- Persistent severe stomach pain, especially if it reaches the back
- Repeated vomiting or signs of significant dehydration
- A severe allergic reaction or trouble breathing
- Sudden loss of vision, including partial loss
For a suspected side effect, speak to a clinician and use the MHRA Yellow Card scheme. Call 999 for a life threatening emergency.
Make the consultation useful
Questions worth asking before you change
- Why do you think Mounjaro is a better fit for me than staying on Wegovy or trying the pill?
- Exactly when should I take my last Wegovy dose and first Mounjaro dose?
- What should I do if I still have side effects on the planned start date?
- Which Mounjaro dose will I start on and when will it be reviewed?
- Could this affect any of my other medicines or blood sugar treatment?
- Who do I contact if symptoms become difficult between reviews?
Independent comparison
Use the right comparison site for the treatment
Prices and provider policies can change quickly. These three sites keep each format separate, which makes the dose and offer easier to check.
Mounjaro prices, provider policies, maintenance information and UK pharmacy routes.
Compare Mounjaro on MonjWegovy injection prices, including the current dose range, discounts and provider checks.
Compare Wegovy injections on iGovyWegovy pill prices, dose information, availability notes and provider checks.
Compare Wegovy pills on OgovyEvidence and accountability
How this guide was checked
Monj’s editorial team checked the current UK licences and dosing information against regulator and manufacturer supplied product information, then checked the trial figures against peer reviewed publications. Monj is not a pharmacy and has not turned the data into a treatment recommendation.
- MHRA: Wegovy tablet UK approvalApproval, eligibility and tablet dosing, 11 June 2026
- eMC: Wegovy tablet SmPCDosing, administration, switching and OASIS 4 data
- eMC: Wegovy injection SmPC2.4 mg and 7.2 mg dosing, STEP and STEP UP data
- eMC: Mounjaro KwikPen SmPCStarting dose, titration, safety and SURMOUNT data
- New England Journal of Medicine: OASIS 4Oral semaglutide 25 mg trial
- New England Journal of Medicine: SURMOUNT-5Direct tirzepatide and semaglutide comparison
- NICE TA875: semaglutideNHS recommendations for weight management and obesity
- NICE TA1026: tirzepatideNHS recommendations and phased implementation information
- MHRA: what patients need to know about GLP-1 medicinesOfficial safety and use information
- Monj GLP Med Compare ToolTrial data, dose context, approval status and labelled estimates
Plain answers
Frequently asked questions
Can I switch straight from Wegovy to Mounjaro?
You may be able to move from one treatment to the other, but the start date must be agreed with a prescriber. There is no universal gap or direct dose conversion. Do not take them together.
Do I always need to wait five weeks after Wegovy?
No fixed five week rule appears in the UK product information for a Wegovy to Mounjaro switch. Semaglutide stays in the body for several weeks, so your prescriber should choose the timing using your last dose, current symptoms and clinical history.
Can I start Mounjaro at a high dose because I used high dose Wegovy?
There is no equivalent dose chart. The licensed Mounjaro starting dose is 2.5 mg once weekly, followed by 5 mg after four weeks. Follow the plan given by your prescriber.
Is Mounjaro proven to work better than Wegovy?
In SURMOUNT-5, tirzepatide produced greater average weight reduction than semaglutide injection at the doses studied. The trial did not include Wegovy 7.2 mg or the Wegovy pill, and a group average cannot tell you which treatment will suit you personally.
Could I use the Wegovy pill instead of changing to Mounjaro?
Possibly. It may be worth discussing if the injection itself is the problem. The pill contains semaglutide and needs strict fasting and timing for reliable absorption. It is not a like for like dose swap for every Wegovy injection dose.
Will Mounjaro cause fewer side effects?
There is no guarantee. Both treatments commonly cause digestive side effects. Some people prefer one, while others tolerate neither well. Tell the prescriber what happened on Wegovy before the new plan is agreed.
