Medically reviewed by Dr Dan McNally.
Mounjaro contains tirzepatide, which acts on both the GLP-1 and GIP receptors. Wegovy acts on GLP-1 alone. That second pathway is the reason Mounjaro produces the largest average weight loss of the options Emerald offers.
Mounjaro: what is it?
Mounjaro is the brand name for tirzepatide. It is a dual agonist, which means it activates two gut hormone receptors rather than one: GLP-1 and GIP. Wegovy, by comparison, acts on GLP-1 alone.
GLP-1 activation reduces appetite and slows gastric emptying. GIP activation appears to add further appetite regulation and to improve how your body handles fat and glucose.
Acting on both pathways is the most likely explanation for the larger average weight loss seen in head to head trials, though individual response still varies widely.
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Dosing schedule
Mounjaro is injected under the skin once a week, on the same day each week. There is no fasting window and no timing rules around meals, so you can take it whenever suits you.
Like all GLP-1 medication, the dose is increased gradually so your body has time to adjust. This is the single most effective way to keep early side effects manageable.
Here is the typical dosing schedule for Mounjaro:
Month 1: 2.5mg
Month 2: 5mg
Month 3: 7.5mg
Month 4: 10mg
Month 5: 12.5mg
Month 6+: 15mg
Mounjaro needs to be kept refrigerated, so plan ahead if you are travelling. Use an insulated case with a cool pack and carry it in hand luggage.
Efficacy
Mounjaro produces the largest average weight loss of the treatments Emerald offers. In SURMOUNT-1, people taking the 15mg dose lost an average of 22.5% of their body weight over 72 weeks under the efficacy estimand. The treatment-regimen analysis, which counts everyone regardless of adherence, gives 20.9%.
SURMOUNT-5 compared the two drugs directly. At 72 weeks, tirzepatide produced 20.2% average weight loss against 13.7% for semaglutide, with both given at maximum tolerated dose.
Acting on two hormone pathways rather than one is the most likely explanation for the difference.
Averages do not tell the whole story. Your own response depends on your starting point, your history with GLP-1 medication, and the habits you build alongside treatment.
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Side Effects
Just as with any other medication, Mounjaro comes with some side effects. Most side effects are mild to moderate, cluster around the start of treatment and each dose increase, and settle on their own.
Contact your Emerald clinician if side effects stop you eating or drinking normally, or if you develop severe or persistent abdominal pain.
Is Wegovy pen right for you?
All the treatments Emerald offers work. The question is which one you can live with day to day.
What works well:
The largest average weight loss of the options Emerald offers
One action per week rather than a daily commitment
No fasting window and no timing rules around meals
Six dose steps, so there is room to find a level that suits you
What to weigh up:
Requires injecting, which is a barrier for some
Needs refrigeration, which complicates travel
Can reduce the effectiveness of oral contraception
Side effects can be more pronounced at the higher doses
This may suit you if:
You have more weight to lose and want the strongest available option
You have tried a GLP-1 before and plateaued
You are comfortable with, or willing to learn, injecting
You have discussed contraception with your clinician, if relevant
How it compares
Emerald offers three treatments. They differ in how you take them, how often, and how much weight people lose on average.
A Emerald clinician will confirm which options are safe and suitable for you before anything is prescribed.
What arrives, and what happens next
Once your assessment is reviewed and your treatment approved, your first delivery arrives in plain packaging with nothing on the outside that names the medication.
Your first delivery includes:
Your Mounjaro KwikPen, containing four weekly doses
Four disposable needles, one per injection
Sharps bin for safe disposal at home
Plan information leaflet with your dose schedule
From there, a UK clinician reviews you at each dose step rather than only at the start. You log your weight and doses in the Emerald app, and you can message the clinical team whenever something does not feel right.
Conclusion
Mounjaro produces the largest average weight loss of the treatments Emerald offers, because it works on two hormone pathways rather than one. That does not automatically make it the right choice for you.
Whichever form you choose, the medication is only part of it. Emerald pairs treatment with clinical review and habit work, because appetite generally returns to its previous pattern once treatment stops.
If you are not sure which is right for you, start the assessment and let a clinician confirm which options are safe and suitable.
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