Over the last year, I’ve seen a surge in interest around weight management medications—particularly Wegovy (semaglutide) and, more recently, Mounjaro (tirzepatide). With media coverage, patient demand, and growing clinical evidence supporting these treatments, they are becoming central to many patients’ weight loss journeys.
One of the most common questions I’m asked—both by patients and fellow practitioners—is:
“Can I switch from Wegovy to Mounjaro?”
The short answer is yes. But the more important answer is: you must understand that these are not the same medications—and switching between them needs to be done with care, medical oversight, and clear expectations.
In this blog, I’m going to explain the difference between Wegovy and Mounjaro, why they’re not interchangeable, and what I recommend when patients are transitioning between them.
Understanding the Medications: Wegovy vs Mounjaro
Let’s begin with the basics.
Wegovy (Semaglutide)
Wegovy is a GLP-1 receptor agonist, a class of drugs that mimics the action of the naturally occurring hormone glucagon-like peptide-1. This hormone works by increasing insulin secretion, suppressing appetite, and slowing gastric emptying, leading to reduced food intake and weight loss.
It’s been widely used, particularly in the UK and the Isle of Man, and has shown consistent, effective results for weight management. Wegovy is typically started at 0.25 mg per week, increasing gradually to a maintenance dose of 2.4 mg weekly.
Mounjaro (Tirzepatide)
Mounjaro is a dual agonist, meaning it mimics the action of two hormones: GLP-1 and GIP (glucose-dependent insulinotropic polypeptide). The addition of GIP makes this drug different—both pharmacologically and physiologically.
In short: Mounjaro is not just a stronger version of Wegovy. It is a different medication.
While Mounjaro is also administered weekly and used for weight management, it has a different mechanism of action, side effect profile, and dosing schedule. Its introduction into the UK and Isle of Man markets has been met with excitement—and rightly so, as it appears to show even more promising results in some patients.
Why You Can’t Compare Them Like-for-Like
This is critical: Wegovy and Mounjaro are not interchangeable in terms of dose.
I’ve had patients ask, “I’m on 1.7 mg of Wegovy, so can I just move to 7.5 mg of Mounjaro?” or “Should I go straight to the same strength?”
The answer is no.
Because tirzepatide (Mounjaro) includes the second hormone GIP, it behaves differently in the body. Some patients find it more effective. Others may experience stronger gastrointestinal side effects—nausea, bloating, diarrhoea—particularly if they jump in at too high a dose.
Even though both drugs target appetite and blood sugar regulation, they do so through different pathways. This means that your body needs time to adjust when making the switch. It’s not just a new number on the pen; it’s a whole new chemical experience for your system.
Recommended Approach: How I Guide My Patients
Step 1: Patient Assessment
Before making any change, we assess the patient’s medical history, current medications, side effects experienced, and current weight trajectory. We also talk about expectations—because one medication doesn’t guarantee better or faster results than the other.
Step 2: Explain the Differences
As a prescriber, I take the time to explain to patients that:
- Wegovy is GLP-1 only
- Mounjaro is GLP-1 and GIP
- The two are not interchangeable in strength or action
- Switching may involve temporary side effects
- We are starting a new treatment—not just continuing the same journey
Step 3: Start Mounjaro at 2.5 mg
No matter what Wegovy dose the patient was on previously, I always recommend starting Mounjaro at the lowest dose—2.5 mg weekly for the first 4 weeks.
This gives the body a chance to adapt to the dual-action therapy without overwhelming the gastrointestinal system. It’s also supported by the manufacturer’s guidance and clinical trials.
Step 4: Titrate Gradually
After 4 weeks, depending on tolerance and effect, we may increase the dose incrementally. Most patients move to 5 mg, then possibly 7.5 mg or 10 mg as needed—but never without reassessment.
Each patient is different. This is not a one-size-fits-all model. The key is monitoring and adjusting.
What Staff and Clinics Must Know
If you’re working in aesthetics or medical weight loss, it’s crucial that your receptionists, nurses, and clinic coordinators understand this distinction too.
Why? Because many patients call asking questions like:
- “Can I switch from Wegovy to Mounjaro?”
- “I’ve got some side effects—should I go back to Wegovy?”
- “Is Mounjaro stronger?”
Your team needs to know that:
- Yes, patients can switch—but it must be medically managed.
- The drugs are not the same, and not directly dose-comparable.
- Starting at 2.5 mg of Mounjaro is non-negotiable.
- Only a face-to-face consultation with a prescriber (doctor, dentist, nurse prescriber, pharmacist) can authorise this change, as per UK regulations.
This isn’t just best practice—it’s a regulatory requirement. The GMC, GDC, NMC and MHRA have all reiterated the importance of face-to-face consultations before prescribing weight loss medications. Delegation may follow, but prescribing must be clinically led and personally assessed.
Common Patient Questions Answered
“Is Mounjaro better than Wegovy?”
Not necessarily—it depends on how your body responds. Some people lose more weight on Mounjaro. Others find Wegovy more tolerable.
“Can I use up my old Wegovy and then switch?”
You must discuss this with your prescriber. In most cases, we finish the current Wegovy course before transitioning—but again, this is clinical judgement.
“Will I gain weight during the switch?”
Possibly not—but don’t expect weight loss to continue at the same pace during the transition. The goal is stability, then progress.
“Can I just order Mounjaro online and switch myself?”
Absolutely not. This is unsafe, non-compliant, and puts you at risk of serious side effects. Always consult a registered prescriber.
Final Thoughts: A Personal Reflection
As a clinician deeply committed to patient-centred care, I believe the introduction of Mounjaro offers fantastic opportunities—but it must be done right.
It’s not about the brand, the hype, or who lost the most weight on Instagram. It’s about sustainable, safe, and medically-led change.
I’ve always said this: the medicine is just one part of the journey. Support, education, behaviour change, and clinical monitoring are what lead to long-term success.
So yes—you can switch from Wegovy to Mounjaro. But please, do it properly. Respect the differences, trust the process, and seek the right guidance.
If you’re a patient considering this change, get in touch. If you’re a practitioner unsure how to guide your clients, feel free to reach out for professional collaboration- always
We learn from each other
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