Why Mounjaro doses are higher than Wegovy doses — and what that actually means

Step 1: understand why the milligram figures don't translate directly

The most common misconception is that Mounjaro's 15mg maximum must be stronger than Wegovy's 2.4mg maintenance dose simply because 15 is bigger than 2.4. It isn't that straightforward. Tirzepatide (the active ingredient in Mounjaro) and semaglutide (the active ingredient in Wegovy) are structurally distinct molecules. They bind to receptors differently, they are absorbed differently, and their effective concentrations at the receptor level aren't proportional to the milligram figure on the pen.

Mounjaro is a dual GIP and GLP-1 receptor agonist, it activates two separate gut-hormone pathways simultaneously. Wegovy targets the GLP-1 pathway alone. Because tirzepatide's mechanism is broader, the molecule itself is engineered and dosed differently to achieve the right degree of receptor activation. The NHS's medicines information for tirzepatide explains this dual-action profile clearly. If you're wondering why Wegovy's dose is lower than Mounjaro's, the answer comes down to how each molecule interacts at a cellular level, not simply what the number on the pen says.

If you want to explore how specific doses map across the two medicines, the Mounjaro equivalent dose to Wegovy guide goes through the clinical thinking in more detail.

Step 2: trace how each dose ladder is designed

Mounjaro starts at 2.5mg (a tolerability step whose job is to let your body adjust, not to drive weight loss) then moves through 5, 7.5, 10, 12.5 and 15mg, typically in roughly four-week increments set by your prescriber. The escalation is gradual deliberately: GI side effects such as nausea, constipation and indigestion are most likely at the start or after a step up, and the slow climb keeps them manageable for most people. Our prescribers review dose increases individually; there's no automatic schedule.

Wegovy's standard pathway runs 0.25mg → 0.5mg → 1.0mg → 1.7mg → 2.4mg, also in roughly four-week steps. The MHRA approved a higher 7.2mg dose in January 2026, initially delivered as three 2.4mg pens per week, with a dedicated single-dose 7.2mg pen approved on 14 April 2026. Trial data at 7.2mg showed around 20.7% average weight loss over 72 weeks, closing the gap with tirzepatide's highest-dose results considerably. Whether a specific dose or pen format is available is confirmed at consultation, not before.

For a closer look at where the two ladders overlap, the Wegovy dose vs Mounjaro comparison page maps out the titration sequences side by side.

Step 3: look at the evidence, side by side

The SURMOUNT-1 trial, published in the New England Journal of Medicine, found that adults taking tirzepatide 15mg lost around 20–21% of body weight on average over 72 weeks. The STEP 1 trial, also published in the New England Journal of Medicine, reported around 15% average weight loss with semaglutide 2.4mg over 68 weeks. In the SURMOUNT-5 head-to-head trial (751 adults, 72 weeks, published in NEJM 2025), tirzepatide produced greater average weight reduction than semaglutide 2.4mg directly, though the 7.2mg semaglutide data narrows that gap. NICE's appraisal of tirzepatide (TA1026) notes that indirect comparisons favour tirzepatide, while acknowledging uncertainty.

The table below summarises the key factual differences. Nothing in it should be read as a recommendation, it is a reference, not a verdict.

If cost is part of your thinking, the Mounjaro and Wegovy price comparison covers what private treatment typically costs for each.

Step 4: what this means for the clinical decision

Knowing that Mounjaro's milligram figures are larger than Wegovy's tells a prescriber almost nothing on its own. What does matter: your starting BMI, any weight-related conditions you have, how you've responded to treatment before, whether you're on oral contraceptives (tirzepatide specifically can reduce absorption of the pill during the first four weeks of treatment and for four weeks after each dose increase, so an additional non-oral method is advised), and your own preferences around injection experience and side-effect profile.

If you're switching between medicines (or curious whether a particular Wegovy dose has a Mounjaro equivalent) that question is worth putting directly to a prescriber rather than working from the numbers alone. The Mounjaro to Wegovy dose conversion page explains the clinical thinking behind how switches are handled, and the broader Wegovy vs Mounjaro overview covers efficacy, side effects and licensing in a single place.

Which medicine suits you is a clinical decision our prescribers make with you, not one any comparison table can settle. If you'd like that conversation, start your free consultation and a GPhC-registered prescriber will review your details the same day.