“My GP mentioned Wegovy. But my friend lost loads of weight on Mounjaro. Are they the same thing? Should I ask for the other one? Does it even matter?”
This is how most consultations at Easy Pharmacy start when patients in Chertsey, Ashford, and Walton-on-Thames first walk through the door.
They’ve done the research. They’ve watched the YouTube videos. They’ve read the Reddit threads. And now they’re more confused than when they started.
Most patients tell Dilip during their first appointment: “I wish someone had just explained the actual difference instead of making me feel like I should already know.”
The confusion makes sense. Both medications get talked about as “weight loss injections.” Both require weekly doses. Both seem to work. And until recently, there wasn’t a direct comparison to answer the obvious question: if you put them head-to-head, does one work better?
In May 2025, that changed. The New England Journal of Medicine published the first trial that tested Mounjaro and Wegovy against each other—same study, same people, same timeframe.
What the data actually shows, and more importantly, what it means for you.
WHAT THE HEAD-TO-HEAD TRIAL ACTUALLY FOUND
The SURMOUNT-5 trial did something most studies don’t: it directly compared Mounjaro and Wegovy in 751 people over 72 weeks.
Everyone in the trial had obesity or was overweight with health concerns (high blood pressure, prediabetes, that sort of thing). Half got Mounjaro at its maximum dose (15mg). Half got Wegovy at its maximum dose (2.4mg). Everyone received the same lifestyle advice.
After 72 weeks:
Mounjaro group:
- Lost 20.2% of their starting weight on average
- If you started at 100kg, that’s losing 20.2kg (ending around 79.8kg)
Wegovy group:
- Lost 13.7% of their starting weight on average
- Starting at 100kg, that’s losing 13.7kg (ending around 86.3kg)
That’s a 6.5kg difference in average results.
More than 9 out of 10 people on Mounjaro (91.7%) lost at least 5% of their weight. Just over 4 out of 10 (42.5%) lost 25% or more—that’s a quarter of their starting weight.
With Wegovy, about 8 out of 10 (81.9%) lost at least 5%. Around 1 in 7 (14%) lost 25% or more.
Patients ask when Dilip shows them these numbers: “So Mounjaro is better?”
Not quite that simple.
WHY “BETTER” IS THE WRONG QUESTION
These are averages from a clinical trial. Some people in the Wegovy group lost more weight than the Mounjaro average. Some people tolerated Wegovy better. Some preferred the dosing schedule.
What the trial tells you: if you took 751 people and randomly gave half Mounjaro and half Wegovy, the Mounjaro group would lose more weight on average.
What it doesn’t tell you: which medication you’ll respond to better.
Dilip explains in consultations: the trial data gives us a starting point. Your individual response over the first 8-12 weeks tells us whether that medication is working for you specifically.
Some patients walk in convinced they want Mounjaro because of the trial results. Three months later, they’re not tolerating the side effects well and we’re discussing switching to Wegovy. Others start on Wegovy, do brilliantly, and never need to consider switching.
The data matters. Your experience on the medication matters more.
THE ACTUAL DIFFERENCE: WHY MOUNJARO MIGHT WORK DIFFERENTLY
Slightly technical, but worth understanding.
Wegovy mimics one hormone: GLP-1 (glucagon-like peptide-1). This hormone tells your brain you’re full and slows down how quickly your stomach empties. You eat less because you genuinely feel less hungry.
Mounjaro mimics two hormones: GLP-1 (same as Wegovy) plus GIP (glucose-dependent insulinotropic polypeptide). The GLP-1 part works the same way—reducing appetite, slowing digestion. The GIP part may help your body process sugar and fat differently, potentially adding to the weight loss effect.
Think of it this way: Wegovy targets one mechanism that controls appetite. Mounjaro targets that same mechanism plus a second one that may affect metabolism.
Does that dual action explain why Mounjaro showed better results in the trial? Probably. Does it mean Mounjaro will definitely work better for you? Not necessarily.
Your body might respond brilliantly to Wegovy’s single-action approach. You might not need the dual mechanism to get the results you’re after.
THE SIDE EFFECTS REALITY: WHAT ACTUALLY HAPPENS
“Which one has worse side effects?”
Every patient asks this. The honest answer from the trial data:
Both medications work through similar pathways (they both use GLP-1), so the side effects are similar:
- Nausea (most common, especially weeks 1-8)
- Diarrhoea or constipation
- Feeling full quickly
- Reduced appetite (which is the point, but can feel strange at first)
In the SURMOUNT-5 trial:
- 6.2% of people on Mounjaro stopped because of side effects
- 4.3% of people on Wegovy stopped because of side effects
That’s remarkably close. Neither medication is clearly “easier to tolerate” based on the numbers.
What matters more than the statistics:
How you personally handle the first 8 weeks. This is where Easy Pharmacy’s face-to-face approach makes the difference. You’re not messaging a chatbot about nausea at 2am. You’ve got a scheduled review coming up where Dilip or one of the in-house weight loss experts can adjust your dose timing, discuss meal strategies, or slow down the escalation if needed.
Most side effects settle as your body adjusts. The patients who stick with treatment long enough to see the 20% weight loss results are the ones who had proper support through those early weeks.
THE DOSING DIFFERENCE: DOES IT MATTER?
Both medications start low and gradually increase over several months. This reduces side effects.
Wegovy escalation:
- Starts at 0.25mg
- Increases every 4 weeks
- Reaches the maintenance dose (2.4mg) after about 16 weeks
- Five dose strengths total
Mounjaro escalation:
- Starts at 2.5mg
- Increases every 4 weeks
- Reaches maintenance (usually 10mg or 15mg) over 3-6 months depending on tolerance
- Six dose strengths total: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, 15mg
Mounjaro has more intermediate doses. In practice, this means slightly more flexibility if you’re between doses—we can go from 7.5mg to 10mg rather than jumping larger gaps.
Does this make a meaningful difference? For some patients, yes. For others, Wegovy’s more standardised schedule feels simpler.
Neither approach is objectively “better.” It depends on your response.
WHAT ACTUALLY HAPPENS AT YOUR EASY PHARMACY CONSULTATION
When you book an appointment to discuss Mounjaro vs Wegovy, the realistic version of what happens:
First 15 minutes:
Dilip or one of the team takes your medical history. Current weight, previous attempts to lose weight, any health conditions (high blood pressure, prediabetes, joint problems), medications you’re on, any history of digestive issues.
This isn’t box-ticking. It’s working out whether either medication is appropriate, or if there’s a reason to avoid one or the other.
Next 10 minutes:
You explain what you’ve already read about both medications. What you’re hoping to achieve. What concerns you have.
Most patients say some version of: “I just want to know which one I should try first.”
The actual decision:
Based on your medical history and what you’ve told us, Dilip will recommend a starting point. Sometimes it’s clear: if you’ve tried Wegovy before and didn’t get on with it, Mounjaro makes sense. If cost is a major factor and Wegovy is more accessible, we start there.
Often, either medication would be clinically appropriate. In which case, the SURMOUNT-5 data suggests starting with Mounjaro gives you slightly better odds of achieving higher weight loss—but we’re monitoring your response either way.
What happens next:
You start on the lowest dose. You inject once weekly. You come back in 4 weeks for your first review.
At that review, we’re looking at: how you’ve tolerated it, whether you’ve noticed appetite changes, any side effects, early weight loss (usually modest at this stage), and whether you’re ready to increase the dose.
If it’s working and you’re tolerating it well, we continue. If you’re struggling with side effects, we slow down. If you’re not seeing any effect after a reasonable trial period, we discuss switching.
The honest truth:
Some patients stay on their first choice for the entire treatment period. Others switch after a few months because their response isn’t what we’d hoped. Both scenarios are completely normal.
The medication that works is the one you can tolerate long enough to see results.
THE SWITCHING QUESTION: “WHAT IF I PICK WRONG?”
“If I start on Wegovy and it doesn’t work, can I switch to Mounjaro?”
Yes. And it happens more often than you’d think.
Some patients start on Wegovy (often because their GP mentioned it first, or because a friend had success with it). After 12-16 weeks, they’ve lost some weight but not as much as they’d hoped. They’ve seen the SURMOUNT-5 data. They want to try Mounjaro.
We support that switch. Your prescriber will guide the transition—there’s usually a washout period, then starting Mounjaro at the lowest dose and escalating again.
The reverse happens too. Patients start on Mounjaro, struggle with nausea at higher doses, and find Wegovy suits them better.
Neither scenario means you “failed.” It means you’re finding what works for your body.
This is where face-to-face monitoring at Easy Pharmacy matters. You’re not locked into a medication choice made by an algorithm. You’ve got an actual prescriber who knows your history and can adjust the plan.
THE QUESTION NOBODY ASKS (BUT SHOULD)
After explaining the SURMOUNT-5 data, the side effects, and the dosing schedules, Dilip usually asks: “What would make this worth it for you?”
Most patients haven’t thought about this specifically. They know they want to lose weight. But what does success actually look like?
Is it fitting into clothes from five years ago? Getting off blood pressure medication? Being able to walk up stairs without getting breathless? Playing with your kids without your knees hurting?
Because the trial data doesn’t capture this: 13.7% weight loss on Wegovy might achieve all of those things for you. You might not need the extra 6.5 percentage points that Mounjaro showed in the trial.
Or you might want maximum possible weight loss and are willing to tolerate potentially more side effects to get there.
There’s no right answer. But knowing what you’re actually aiming for makes it easier to decide which medication to try first—and when to consider switching if you’re not getting there.
IMPORTANT SAFETY INFORMATION
Both Mounjaro and Wegovy carry the same thyroid tumour warning:
In rodent studies, these medications caused thyroid C-cell tumors. We don’t know if this happens in humans. Both medications are not suitable for anyone with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2.
Both medications may also cause pancreatitis, gallbladder problems, kidney problems (especially if you become dehydrated from nausea or vomiting), low blood sugar, changes in vision, increased heart rate, or allergic reactions.
Dilip or one of the weight loss specialists at Easy Pharmacy will discuss these risks during your consultation and assess whether either medication is appropriate for your medical history.
STARTING TREATMENT: WHAT ACTUALLY HAPPENS
Step 1: Call 01784 255 222 or email hello@easypharmacy.co.uk
Step 2: Book your consultation (usually available same-day or within 24-48 hours)
Step 3: Consultation with Dilip or one of the in-house weight loss experts at Easy Pharmacy in Chertsey (serving patients across Chertsey, Ashford, and Walton-on-Thames)
Step 4: If clinically appropriate, you start on whichever medication makes sense for your situation—either Mounjaro or Wegovy, at the lowest dose
Step 5: Monthly face-to-face reviews to monitor progress, manage side effects, adjust doses, and decide whether to continue or switch
No GP referral needed. No months-long waiting list. No being told “you don’t qualify.”
If you meet the clinical criteria (BMI 27+ with weight-related health concerns, or BMI 30+), and neither medication is contraindicated based on your medical history, you can start.
Ready to take the next step?
Book your consultation with Easy Pharmacy in Surrey. Same-day and next-day appointments usually available.
