Dose conversion guide: Mounjaro to Wegovy
When switching from Mounjaro to Wegovy, your prescriber may start you at a higher dose than the standard 0.25 mg if they deem it appropriate based on your current dose and tolerance.
There’s no official conversion chart that matches a given Mounjaro dose to an exact Wegovy dose, so these are possible starting doses your prescriber might consider rather than fixed recommendations.
| Current Mounjaro dose |
Possible Wegovy starting dose |
Notes |
| 2.5 mg |
0.25 mg |
Standard licensed starting dose |
| 5 mg |
0.25-0.5 mg |
Higher doses are off-label |
| 7.5 mg |
0.5-1 mg |
Based on side effect history |
| 10 mg |
1 mg |
Off-label starting dose |
| 12.5 mg |
1-1.7 mg |
Prescriber discretion |
| 15 mg |
1.7 mg |
May still need escalation |
A note on ‘off-label’ dosing: Wegovy’s licensed starting dose is 0.25 mg.
Starting at a higher dose is technically off-label but is commonly used in specialist obesity practice when switching from another GLP-1 medication. Your prescriber will assess your tolerance and determine the safest approach.
If you experienced significant side effects with Mounjaro, your prescriber may recommend starting at a lower dose of Wegovy than shown above.
Whichever dose you start at, the licensed Wegovy maintenance dose is 2.4 mg. If you were on a higher Mounjaro dose and want to match the weight loss you had before, your prescriber may aim for the 7.2 mg Wegovy dose over time, once you have titrated up and tolerated 2.4 mg well.
Still, Second Nature recommend staying on the lowest effective dose for as long as possible. If you’re losing weight sustainably, there’s no clinical need to increase your dose.
Key differences: Mounjaro vs Wegovy
| Feature |
Mounjaro (tirzepatide) |
Wegovy (semaglutide) |
| Mechanism |
Dual GLP-1 and GIP receptor agonist |
GLP-1 receptor agonist only |
| Cardiovascular benefits |
Non-inferior to another GLP-1 (dulaglutide) for cardiac events in SURPASS-CVOT, with a 16% lower risk of death from any cause; not yet licensed for CVD reduction5 |
20% reduction in major cardiac events (SELECT trial); licensed for CVD risk reduction3 |
| Oral contraceptive interaction |
Can substantially reduce absorption (up to around two-thirds in some measures)4 |
No clinically relevant interaction4 |
| Pen priming |
Required before every injection |
Required once per pen only |
| Room temperature storage |
Up to 30 days |
Up to 42 days |
| Clinical trial weight loss |
Around 20% at the top dose1 |
Around 15% at 2.4 mg; 20.7% at 7.2 mg2,7 |
| Dose options |
6 doses (2.5-15 mg) |
6 doses (0.25-7.2 mg) |
| UK availability |
Private and limited NHS |
Private and NHS (where criteria met) |
Cardiovascular benefits and weight loss comparison
Both medications have shown cardiovascular benefits in clinical trials, though only Wegovy currently holds a UK licence for cardiovascular risk reduction.
The SELECT trial, which included 17,604 participants with established cardiovascular disease, found that semaglutide (Wegovy) reduced the risk of major adverse cardiovascular events (MACE) by 20% compared with placebo.3
MACE includes cardiovascular death, non-fatal heart attack, and non-fatal stroke. Based on these findings, the MHRA approved Wegovy for cardiovascular risk reduction in July 2024.
Tirzepatide (Mounjaro) has also shown cardiovascular benefits.
In the SURPASS-CVOT trial, which compared it with another GLP-1 medication (dulaglutide) rather than a placebo, tirzepatide was non-inferior for major cardiovascular events and reduced the risk of death from any cause by 16%.5
Mounjaro doesn’t yet hold a UK licence for cardiovascular risk reduction. A regulatory decision is expected to follow as the data are reviewed.
The most important current difference is regulatory: Wegovy is licensed to reduce cardiovascular risk, whereas tirzepatide’s cardiovascular licence is still being assessed. This means prescribers can specifically recommend Wegovy for patients with established heart disease, whereas Mounjaro’s cardiovascular benefits, while observed, are not yet part of its licensed uses.
If you have established cardiovascular disease or significant risk factors, discuss with your prescriber whether that licensed cardiovascular benefit is an important consideration for your treatment choice.
Weight loss: trials and real-world data
Clinical trials suggest Mounjaro produces greater weight loss than the 2.4 mg dose of Wegovy (around 20% versus around 15%).1,2
The higher 7.2 mg Wegovy dose, available since January 2026, produced around 20.7% in its own trial (STEP UP), which is comparable to Mounjaro.7 So the two drugs now support similar weight-loss results on average.
Real-world data also suggest the gap at standard doses may be smaller than trials indicate. On Second Nature’s programme, our members lose a similar amount of weight with both medications.
A 12-month retrospective study published in JMIR Formative Research compared outcomes for participants using either tirzepatide or semaglutide within the same behavioural support programme.6 The results showed:
- Tirzepatide users lost an average of 22.1% of their starting weight
- Semaglutide users lost an average of 17.1% of their starting weight
While tirzepatide showed greater average weight loss, both medications exceeded the 10% threshold considered clinically significant, with 95.2% of tirzepatide users and 83.1% of semaglutide users achieving this level of weight loss.
It’s worth noting that this was an observational study, not a randomised trial that compared the two directly, so the comparison has limitations.
However, it suggests that in real-world settings with appropriate lifestyle support, the difference between the medications may be smaller than trial data indicate.
Individual responses vary considerably, and some people respond better to one medication than the other.
Contraception considerations when switching
If you use oral contraceptives (the pill), there’s an important difference between these medications you should know about.
Mounjaro and oral contraceptives: Tirzepatide (Mounjaro) can substantially reduce the absorption of oral contraceptive pills (up to around two-thirds in some pharmacokinetic measures), potentially making them less effective.4
The manufacturer recommends using barrier contraception (such as condoms) for 4 weeks after starting Mounjaro and after each dose increase.
Wegovy and oral contraceptives: Semaglutide (Wegovy) has no clinically relevant effect on the absorption or effectiveness of oral contraceptives.4 No additional precautions are needed. This applies to both the Wegovy injection and the Wegovy pill.
Non-oral contraceptives: Neither medication affects non-oral contraceptives, including:
- Contraceptive patch
- Vaginal ring
- Hormonal IUD (coil)
- Contraceptive implant
- Contraceptive injection
If you’re currently using the pill while on Mounjaro and want to continue using oral contraception after switching, Wegovy offers the advantage of no interaction concerns.
What to expect when switching
The transition between these medications typically goes smoothly, but you may notice some changes.
During the washout period
The gap between stopping Mounjaro and starting Wegovy is short and doesn’t usually affect your progress:
- Tirzepatide has a half-life of around 5 days, meaning it remains active in your system for several days after your last injection
- Many people do not notice major appetite changes during a short washout period
- A short washout, such as 7 days, is not usually associated with marked weight regain, especially if lifestyle habits are maintained
First few weeks on Wegovy
The body needs time to adjust to the different medication. Wegovy works by mimicking one hormone (GLP-1), while Mounjaro mimics two (GLP-1 and GIP).
Appetite changes: You may notice slightly different hunger patterns initially. Some people report increased hunger during the first 2-3 weeks before the medication reaches full effect. Others notice no difference at all.
Side effects: You may experience different side effects as the medications work through slightly different pathways:
- Nausea and digestive symptoms may temporarily increase or change
- Some people report less fatigue with Wegovy compared to Mounjaro
- Headaches sometimes occur during the transition, but typically resolve
Weight: Your weight may fluctuate slightly during the transition. This is normal and doesn’t mean the medication isn’t working. Once you reach your maintenance dose, weight loss typically continues.
Common myths about switching
There’s a lot of misinformation about switching between these medications. Here’s what the evidence actually shows.
Myth: You’ll regain weight when switching
Reality: With a short washout period, significant weight regain is unlikely. Tirzepatide remains active in your system during this time, and Wegovy begins working shortly after your first injection.
In clinical practice, most people maintain their weight throughout the transition, especially when lifestyle habits are maintained.
Myth: You have to start at the lowest Wegovy dose
Reality: While the licensed starting dose is 0.25 mg, prescribers commonly start patients switching from Mounjaro at higher doses based on their current dose and tolerance. This is commonly used in specialist obesity practice and generally safe when supervised by an experienced prescriber, though anything above 0.25 mg is technically off-label.
Myth: Wegovy is ‘weaker’ than Mounjaro
Reality: Wegovy and Mounjaro work in different ways. In trials, the 2.4 mg Wegovy dose produced an average weight loss of around 15%, the 7.2 mg Wegovy dose around 20%, and Mounjaro around 20%.
The right option depends on the individual, and some people lose more weight on Wegovy.1,7
Myth: You need weeks off between medications
Reality: A commonly used protocol is 7 days between your last Mounjaro dose and first Wegovy injection, though some product information and clinics advise longer gaps (up to 30 days).
Your prescriber will balance this against the risk of interrupting treatment. There’s no single national standard, and different services use slightly different intervals.
Myth: Once you switch, you can’t go back
Reality: You can switch back to Mounjaro later if needed, under medical supervision. However, you would need to follow a similar protocol, potentially starting at a lower dose of Mounjaro.
How to switch safely from Mounjaro to Wegovy
Switching between these medications should follow a structured approach under medical supervision.
Step 1: Medical assessment
Before switching, your prescriber will evaluate:
- Your current Mounjaro dose and how long you’ve been on it
- Your weight loss progress so far
- Any side effects you’ve experienced
- Your overall health status and any other medications
- Your reasons for wanting to switch
Step 2: Timing the transition
- Take your final Mounjaro injection as scheduled
- Wait for the interval recommended by your prescriber (commonly 7 days, though this may vary)
- Start Wegovy at the dose recommended by your prescriber
- Continue injecting on the same day each week
Step 3: Dose escalation
If you’re starting at a lower Wegovy dose than your maintenance target, you’ll follow this escalation schedule:
- 0.25 mg for 4 weeks
- 0.5 mg for 4 weeks
- 1 mg for 4 weeks
- 1.7 mg for 4 weeks
- 2.4 mg maintenance dose
Your prescriber may adjust this schedule based on your starting dose and your response. If you need more weight loss than the 2.4 mg dose provides, the 7.2 mg dose is available once you’ve tolerated 2.4 mg well.
Step 4: Follow-up
Schedule a follow-up appointment 2-4 weeks after starting Wegovy to assess your response and address any concerns.
Managing side effects during the transition
Some people experience temporary side effects when switching between GLP-1 medications. Here are practical approaches to managing the most common issues.
Nausea and digestive discomfort
- Eat three balanced meals a day based on whole foods
- Choose easy-to-digest foods during the first few weeks, such as scrambled eggs, white fish, and cooked vegetables
- Stay well hydrated between meals (aim for 2 litres daily)
- Limit the intake of ultra-processed foods and takeaways
- Consider ginger tea or supplements, which may help reduce nausea in some people
Fatigue
- Ensure adequate protein intake at each meal
- Include iron-rich foods like red meat and spinach alongside vitamin C sources
- Maintain consistent sleep habits
- Don’t skip meals, even if your appetite is reduced
Changes in appetite
- Maintain three balanced meals a day based on whole foods, even if hunger is low
- Include a protein-rich food at each meal, roughly a palm-sized portion
- Include plenty of non-starchy vegetables to maximise the nutrient density of meals
- Plan healthy snacks for times when hunger might increase
Most transition-related side effects resolve within 2-4 weeks as the body adjusts to the new medication.
Frequently asked questions
Will I regain weight when switching from Mounjaro to Wegovy?
Significant weight regain during the switch is unlikely. Mounjaro stays active in your body for several days after your last dose, so its hunger-lowering effect will remain while Wegovy begins to take effect.
In clinical practice, most people maintain their weight throughout the transition, especially when lifestyle habits are maintained.
Do I have to start Wegovy at the lowest dose?
Not necessarily. While the licensed starting dose is 0.25 mg, prescribers commonly start patients switching from Mounjaro at higher doses.
Your starting dose depends on your current Mounjaro dose, your tolerance, and your prescriber’s assessment. Starting above 0.25 mg is off-label but commonly used in specialist practice.
Can I switch back to Mounjaro later?
Yes, switching back is possible under medical supervision.
You would follow a similar protocol, likely starting at a lower Mounjaro dose and titrating up.
However, factors like cost and availability may affect this decision.
Which medication has worse side effects?
Neither medication consistently has worse side effects. Responses are highly individual:
- Some people report less nausea with Wegovy than Mounjaro
- Others experience fewer digestive issues with Mounjaro
- Both medications can cause similar side effects (nausea, constipation, fatigue)
- The intensity often depends on how quickly doses are escalated
Does Wegovy affect my contraceptive pill?
No. Unlike Mounjaro, Wegovy (semaglutide) has no clinically relevant effect on oral contraceptives, in either its injection or pill form.4 This is an advantage if you rely on the pill for contraception.
Should I switch to the Wegovy pill instead of the injection?
The Wegovy pill is the same drug as the injection and produces similar weight loss to the 2.4 mg injection in trials (around 13.6%), but less than Mounjaro or the 7.2 mg injection.8
It mainly suits people who would rather take a daily tablet than a weekly injection. Our guide to switching to the Wegovy pill covers this in detail.
Why do some prescribers use 7 days rather than 30?
While some manufacturer guidance suggests 30 days, many UK prescribers use a 7-day protocol.
This shorter gap is based on clinical experience suggesting it’s safe and effective, while avoiding prolonged treatment interruption that could affect weight-loss progress.
However, there’s no single national standard, and your prescriber will advise based on your individual circumstances.
How long will it take for me to feel normal on Wegovy?
Most people adjust within 2-4 weeks after starting Wegovy. Any initial side effects or appetite fluctuations typically stabilise during this time.
Reaching your maintenance dose takes 4-5 months following the standard escalation schedule.
What if my appetite comes back strongly during the switch?
Some temporary increase in appetite is normal and doesn’t mean the medication won’t work. Continue eating regular, balanced meals with adequate protein.
Once Wegovy reaches therapeutic levels, appetite suppression typically returns. Contact your prescriber if you’re concerned.
Is Wegovy as effective as Mounjaro for weight loss?
At standard doses, clinical trials show Mounjaro produces higher average weight loss (around 20% versus around 15% for the 2.4 mg Wegovy dose).1,2
The higher 7.2 mg Wegovy dose produced around 20.7% weight loss, comparable to Mounjaro.7
Real-world observational data from Second Nature’s programme show a smaller gap at standard doses, with tirzepatide users losing 22.1% and semaglutide users losing 17.1% of their starting weight at 12 months, though this was not a randomised comparison.6
Individual responses vary, and some people achieve similar results with Wegovy.
How much does Wegovy cost compared to Mounjaro?
Following Eli Lilly’s price increase in September 2025, Wegovy is generally more affordable than Mounjaro at standard doses. At Second Nature, the ongoing monthly cost on the 12-month plan is:
- Wegovy (injection): from around £134 per month, rising to £224 at the standard 2.4 mg dose and £304 at 7.2 mg
- Mounjaro: from around £204 per month, rising to £324 at the top 15 mg dose
Prices vary between providers and over time; check current pricing with your chosen pharmacy or clinic.
NHS patients typically pay only the standard prescription charge (£9.90 per item in England) for either medication if they meet eligibility criteria.
Take home message
Switching from Mounjaro to Wegovy is safe and straightforward when done under medical supervision.
A short washout period (commonly 7 days, though this varies by prescriber) is usually enough to maintain treatment without interruption, and most people transition without significant issues.
In clinical trials, Mounjaro produced a higher average weight loss than the 2.4 mg dose of Wegovy.
On our own programme, that difference was smaller when medication was combined with lifestyle support.
The higher 7.2 mg Wegovy dose produced an average weight loss of around 20.7% in its trial, so a larger weight loss is possible with Wegovy at that dose.
Wegovy is also licensed to help reduce cardiovascular risk, and it doesn’t interact with the oral contraceptive pill, both of which may be relevant depending on your health and circumstances.
Second Nature's Mounjaro and Wegovy programmes
Second Nature provides Mounjaro or Wegovy as part of our Mounjaro and Wegovy weight-loss programmes.
Why choose Second Nature over other medication providers, assuming you're eligible?
Because peace of mind matters.
We've had the privilege of working with the NHS for over eight years, helping people across the UK take meaningful steps toward a healthier, happier life.
Our programmes are designed to meet people where they are, whether that means support with weight loss through compassionate one-to-one health coaching, or access to the latest weight-loss medications (like Mounjaro and Wegovy) delivered alongside expert care from a multidisciplinary team of doctors, psychologists, dietitians, and personal trainers.
At the heart of everything we do is a simple belief: real, lasting change comes from building better habits, not relying on quick fixes. We're here to support that change every step of the way.
With over a decade of experience, thousands of lives changed, and a long-standing record of delivering programmes used by the NHS, we believe we're the UK's most trusted weight-loss programme.
We hope to offer you something invaluable: peace of mind, and the support you need to take that first step.
