The landscape of weight loss has been completely transformed by the arrival of two breakthrough medications: Wegovy (semaglutide) and Mounjaro (tirzepatide). Both are incredibly effective, MHRA-approved injectable treatments, but they work in slightly different ways.
If you are considering starting a clinical weight management plan with Prescriptly, understanding the difference between these two treatments is the first step.
How They Work
Wegovy (Semaglutide)
Wegovy is a single-agonist medication. It mimics a naturally occurring hormone in your body called GLP-1 (Glucagon-Like Peptide-1). By binding to GLP-1 receptors in the brain, it regulates your appetite, significantly reducing feelings of hunger and increasing your sense of fullness after smaller meals. It also slows down gastric emptying, keeping you satisfied for longer.
Mounjaro (Tirzepatide)
Mounjaro represents the next generation of these treatments. It is a dual-agonist, meaning it mimics two hormones: GLP-1 and GIP (Glucose-Dependent Insulinotropic Polypeptide).
While the GLP-1 component works similarly to Wegovy to suppress appetite, the GIP component works synergistically to further improve how the body breaks down sugar and fat. This dual action makes Mounjaro incredibly potent.
Efficacy: How Much Weight Can You Lose?
Both medications offer life-changing results, but clinical trials show a slight edge for Mounjaro.
- Wegovy Results: In the pivotal STEP clinical trials, patients taking the maximum dose of Wegovy (2.4mg) lost an average of 15% of their body weight over 68 weeks.
- Mounjaro Results: In the SURMOUNT clinical trials, patients taking the maximum dose of Mounjaro (15mg) lost an average of 20% to 22.5% of their body weight over 72 weeks.
While Mounjaro statistically leads to greater absolute weight loss, a 15% reduction with Wegovy is still considered highly clinically significant and dramatically improves cardiovascular health and mobility.
Dosage and Administration
Both medications are administered via a once-weekly injection using a virtually painless, pre-filled pen.
- Wegovy: You start on a 0.25mg dose and gradually titrate up every 4 weeks until you reach the maintenance dose of 2.4mg.
- Mounjaro: You start on a 2.5mg dose and titrate up every 4 weeks, with maintenance doses typically ranging between 5mg, 10mg, or 15mg depending on your individual response.
Mounjaro’s KwikPen device contains four doses in a single pen, meaning you only need one pen per month, whereas some Wegovy distributions utilize single-use pens (four pens per month).
Side Effects
Because both medications work by altering gut motility and digestion, their side effect profiles are very similar. The most common side effects include:
- Nausea
- Diarrhea or Constipation
- Vomiting
- Fatigue
- Acid Reflux
These side effects are typically mild to moderate and are most pronounced during the dose-escalation phase. Most patients find that side effects subside completely as their body adjusts to the medication. Our clinicians at Prescriptly provide comprehensive guidance on how to manage these symptoms through diet and hydration.
Which Should You Choose?
There is no one-size-fits-all answer.
- Wegovy has been on the market slightly longer specifically for weight loss and has extensive, long-term cardiovascular safety data behind it (showing a 20% reduction in major adverse cardiovascular events).
- Mounjaro offers the highest potential for total weight loss and may be preferable for patients with significant insulin resistance.
During your free online consultation at Prescriptly, our expert clinical team will review your medical history, BMI, and weight loss goals to recommend the medication that is safest and most effective for your unique biology.