Should You Switch from Mounjaro to Wegovy?

A Look at the Current Evidence and Comprehensive Guide to Making the Right Choice.

Written by Dr Francis O'Neill, our in house specialist in clinical research.
Last reviewed 16/09/25

 

Important Disclaimer

IMPORTANT DISCLAIMER: This guide is for educational purposes only. All treatment decisions must be made in consultation with a qualified healthcare professional who can assess your individual medical situation.

If you've been taking Mounjaro (tirzepatide) for weight loss, you might be wondering whether switching to Wegovy (semaglutide) could be the right move for you. This decision isn't straightforward, and the choice between these two groundbreaking medications involves weighing multiple factors including effectiveness, long-term outcomes, cardiovascular benefits, and practical considerations like cost and availability.

In this comprehensive guide, we'll explore everything you need to know about switching from Mounjaro to Wegovy, including the latest clinical evidence, what to expect during the transition, and how to make an informed decision with your healthcare provider.

Understanding the Key Differences: Mounjaro vs. Wegovy

Before diving into the switching process, it's crucial to understand what makes these medications different and why someone might consider making the change.

Mounjaro (tirzepatide) is a dual agonist targeting both GLP-1 and GIP receptors. Think of it like “filling a basin with both taps turned on” – this dual mechanism potentially offers enhanced effectiveness for weight loss. It's the newer treatment on the block, approved for weight management in late 2023.

Wegovy (semaglutide) is a GLP-1 receptor agonist that mimics hormones released after eating to control blood sugar, slow digestion, and promote satiety. Whilst it has a single mechanism of action, it has been around longer and has accumulated substantial long-term data.

The Clinical Evidence: What the Studies Really Tell Us

Short-term Weight Loss: Mounjaro Takes the Lead

When it comes to initial weight loss, the evidence clearly favours Mounjaro. The SURMOUNT-1 trial demonstrated impressive results with tirzepatide achieving up to 22.5% weight reduction over 72 weeks. But the real game-changer came with the SURMOUNT-5 trial – the first direct head-to-head comparison between these medications.

Published in the New England Journal of Medicine in 2025, SURMOUNT-5 definitively showed Mounjaro's superiority for initial weight loss, with participants achieving an average of 20.2% weight reduction compared to 13.7% with Wegovy. That's a 47% greater relative weight loss – a substantial difference that caught the attention of both healthcare providers and patients.

In contrast, Wegovy's STEP trials showed solid but more modest results, with an average 15.2% weight loss over 104 weeks. Whilst this is still clinically significant, it's clear that if your primary goal is rapid, dramatic weight loss, Mounjaro has the edge.

Long-term Maintenance: Where Wegovy Shines

Here's where the picture becomes more complex and interesting. Whilst Mounjaro excels at initial weight loss, Wegovy has something that's incredibly rare in obesity medicine: proven long-term maintenance data.

The SELECT trial, a landmark study following over 17,000 participants for nearly four years, showed that Wegovy users maintained an average of 10.2% weight loss over this extended period. This is crucial because weight regain is unfortunately common with obesity treatments, making sustained effectiveness perhaps more important than initial dramatic results.

Currently, we don't have comparable long-term data for Mounjaro beyond the initial trial periods. This represents a significant knowledge gap, but it's one that favours Wegovy for patients prioritising long-term success over short-term dramatic results.

Cardiovascular Benefits: A Unique Wegovy Advantage

Perhaps the most compelling reason to consider switching to Wegovy is its proven cardiovascular protection. The SELECT trial didn't just show weight maintenance – it demonstrated a 20% reduction in major adverse cardiovascular events (MACE), including heart attacks, strokes, and cardiovascular death.

This cardiovascular benefit extends beyond weight loss alone and represents additional therapeutic value, particularly for patients with existing heart disease risk factors. Mounjaro's cardiovascular outcome trials are still ongoing, so we don't yet know how it compares in this crucial area.

For patients with hypertension, diabetes risk, or existing cardiovascular disease, this proven cardioprotective effect could be a decisive factor in choosing Wegovy, even if it means sacrificing some initial weight loss potential.

Why Consider Switching from Mounjaro to Wegovy?

  1. Proven Long-term Success
    If you're looking at this as a lifelong journey rather than a quick fix, Wegovy's four-year maintenance data provides confidence that your results will be sustainable. Weight cycling – losing weight only to regain it – is one of the most frustrating aspects of obesity treatment, and Wegovy's track record suggests better long-term outcomes.
  2. Cardiovascular Protection
    For patients with heart disease risk factors, the proven MACE reduction with Wegovy offers benefits that extend far beyond the scales. This could literally be a life-saving consideration for the right patient.
  3. Cost has become a major concern
    Recent Mounjaro price increases have made it significantly more expensive, and Wegovy's broader insurance coverage might make long-term treatment more financially feasible.
  4. Side Effect Profile
    Whilst both medications have similar gastrointestinal side effects, some patients find they tolerate one better than the other. If you're experiencing persistent side effects with Mounjaro, switching might provide relief.
  5. Established Safety Profile
    Wegovy has been on the market longer with extensive real-world safety data across diverse populations. For patients prioritising a well-understood safety profile, this extensive track record provides reassurance.

The Critical Evidence Gap: No Switching Studies Exist

Here's something crucial that every patient considering this switch needs to understand: there are currently no published clinical trials specifically examining switching from Mounjaro to Wegovy for weight loss. This represents a significant limitation in our knowledge.

What this means:

  • All switching protocols are based on clinical experience and expert opinion rather than controlled research data
  • We don't have definitive evidence on optimal switching methods, timing, or outcomes
  • Healthcare providers are working from theoretical safety considerations and clinical judgement

However, existing clinical guidelines from healthcare providers suggest that medication switching can be managed safely without adverse events when properly supervised. The lack of formal studies doesn't mean switching is unsafe – it simply means the protocols aren't based on randomised controlled trials.

Sequential therapy (a clinical possibility): Using Mounjaro for initial rapid weight loss followed by switching to Wegovy for long-term maintenance could theoretically combine the best of both medications. This “sequential therapy” approach – leveraging Mounjaro's superior short-term effectiveness and Wegovy's proven long-term sustainability – is clinically plausible and could potentially result in optimal maintained weight loss outcomes. Unfortunately, no pharmaceutical company has commercial incentive to study this approach, leaving healthcare providers to develop these strategies based on clinical experience and logical therapeutic reasoning.

How to Switch Safely: Understanding the Conflicting Protocols

One of the most confusing aspects of switching between these medications is that different healthcare providers recommend different approaches. This isn't due to medical uncertainty about safety, but rather reflects varying clinical philosophies and risk assessment.

Protocol A: The Conservative Medical Approach

Most traditional medical guidelines recommend a washout period:

Washout Requirements:

  • Low-dose Mounjaro (<7.5mg): Stop for 2 weeks
  • High-dose Mounjaro (≥7.5mg): Stop for 4 weeks

Wegovy Titration Schedule:

  • Weeks 1-4: 0.25mg weekly
  • Weeks 5-8: 0.5mg weekly
  • Weeks 9-12: 1.0mg weekly
  • Weeks 13-16: 1.7mg weekly
  • Weeks 17+: 2.4mg weekly (maintenance)

Why the washout? Both medications work on similar pathways, and overlapping them could theoretically cause severe gastrointestinal side effects, dangerous blood sugar drops, or unpredictable drug interactions.

Protocol B: The Direct Conversion Approach

At DoToR we recommend the direct conversion approach, which is similar to most private providers, including services like Boots Online Doctor, who suggest direct conversion without washout periods:

Direct Dose Equivalents:

  • Mounjaro 2.5mg → Wegovy 0.25mg
  • Mounjaro 5mg → Wegovy 0.5mg
  • Mounjaro 7.5mg+ → Wegovy 0.5 to 1.0mg
  • Mounjaro 10mg → Wegovy 1.0 to 1.7mg
  • Mounjaro 12.5mg → Wegovy 1.7 to 2.4mg
  • Mounjaro 15mg+ → Wegovy 2.4mg

Advantages: No treatment interruption, faster return to therapeutic effect, potentially less weight regain during transition.

What to Expect During Your Switch

If Following the Washout Approach

During the washout period:

  • Your appetite will likely return as the medication leaves your system
  • You may experience some weight regain (typically temporary)
  • Previous side effects should resolve completely
  • This can be psychologically challenging but is usually temporary

When starting Wegovy:

  • Initial side effects (nausea, stomach upset) may return as your body adjusts to the new medication
  • Weight loss will pause during the titration period
  • You may experience less dramatic initial results compared to your Mounjaro experience
  • Full effectiveness is delayed until reaching the 2.4mg maintenance dose

If Following Direct Conversion

Immediate transition:

  • No treatment gap or appetite return
  • Continued therapeutic effect throughout the switch
  • Potentially different side effect profile as your body adjusts to the new mechanism
  • Possible need for dose adjustments based on individual response

Timeline Expectations

Conservative approach:

  • Minimum switch duration: 5-9 weeks
  • Return to effective weight loss: 6-10 weeks
  • Reach maintenance dose: 17+ weeks

Direct conversion:

  • Immediate switch possible
  • No treatment interruption
  • Faster return to stable therapeutic effect

Making the Decision: Is Switching Right for You?

The decision to switch from Mounjaro to Wegovy is highly individual and should be based on your specific circumstances, goals, and medical profile. Here are key factors to consider:

Consider Switching to Wegovy If:

  • You prioritise long-term sustainability...
  • You have cardiovascular risk factors...
  • Cost has become a major concern...
  • You're experiencing side effects with Mounjaro...
  • You value established safety data...

Consider Staying with Mounjaro If:

  • You're achieving excellent results...
  • You prioritise maximum weight loss...
  • You're early in your treatment journey...
  • You're concerned about treatment interruption...

Cost Considerations: The Financial Reality

The financial aspect of these medications can't be ignored, especially with recent significant price increases for Mounjaro making cost a major factor in treatment decisions.

Recent Price Changes:

  • Mounjaro costs have increased substantially in 2025...
  • However, Wegovy is available at established prices...

Regardless, weight loss following GLP-1 administration is likely to have a beneficial impact on healthcare and patients should consider a strategy to facilitate and maintain weight loss.

The Importance of Medical Supervision

Given the conflicting protocols and lack of switching studies, medical supervision throughout this process is absolutely essential. Your healthcare provider will:

Assess your individual situation:

  • Current Mounjaro dose and treatment duration
  • Previous side effects and tolerance patterns
  • Medical history and cardiovascular risk factors
  • Treatment goals and timeline preferences

Determine the appropriate protocol:

  • Whether a washout period is necessary...
  • Starting dose and titration schedule for Wegovy
  • Monitoring schedule and follow-up appointments
  • Contingency plans if the switch doesn't go smoothly

Provide ongoing monitoring:

  • Regular check-ins during the transition period
  • Adjustment of doses based on your response and tolerance
  • Management of any side effects that arise
  • Long-term tracking of weight loss and health outcomes

Looking to the Future: What We Need to Know

  • Switching Studies...
  • Long-term Mounjaro Data...
  • Cardiovascular Outcomes...
  • Real-world Switching Experiences...
  • Cost-effectiveness Research...

The Bottom Line: Making an Informed Choice

Switching from Mounjaro to Wegovy represents a trade-off between superior short-term effectiveness and proven long-term sustainability with cardiovascular benefits...

Key takeaways:

  1. Mounjaro excels at initial weight loss...
  2. Wegovy offers evidenced based cardiovascular protection...
  3. No switching studies exist...
  4. Multiple switching protocols exist...
  5. Individual factors matter most...

Why comparison data is limited: Pharmaceutical companies have no financial incentive...

The untested clinical opportunity: A therapeutic approach using Mounjaro for rapid initial weight loss followed by switching to Wegovy for long-term maintenance... However, no pharmaceutical company will fund studies of this approach since it doesn't exclusively benefit either product.

The decision to switch should be based on a comprehensive evaluation... Whilst the lack of switching studies means we're working without perfect evidence, the clinical experience suggests that for the right patient, switching from Mounjaro to Wegovy can be both safe and beneficial.

Remember: This guide provides background information... Your provider has access to your complete medical picture and can ensure safe, effective treatment transitions tailored to your specific needs.

Whether you decide to switch or stay with your current treatment, the most important factor is finding a sustainable, effective approach that fits your life and health goals – and that decision is best made in partnership with qualified medical professionals who know you and your situation.

References

  1. Jastreboff AM, Aronne LJ, Ahmad NN, et al., for the SURMOUNT-1 Investigators. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216. doi:10.1056/NEJMoa2206038
  2. Aronne LJ, Horn DB, le Roux CW, et al., for the SURMOUNT-5 Trial Investigators. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. N Engl J Med. 2025;393(1):31-42. doi:10.1056/NEJMoa2416394
  3. Lincoff AM, Brown-Frandsen K, Colhoun HM, et al., for the SELECT Trial Investigators. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. N Engl J Med. 2023;389(24):2221-2232. doi:10.1056/NEJMoa2307563
  4. Ryan DH, Lingvay I, Colhoun HM, et al. Long-term weight loss effects of semaglutide in obesity without diabetes in the SELECT trial. Nat Med. 2024;30(8):2049-2057. doi:10.1038/s41591-024-02996-7