Mounjaro vs Wegovy

The basic distinction

Tirzepatide acts at GIP and GLP-1 receptors; semaglutide acts at GLP-1 receptors. Both are prescription medicines with weight-management uses, but different molecular mechanisms do not, by themselves, tell us which will suit an individual. That requires evidence and a clinical assessment. [2][3]

Mounjaro's KwikPen provides four weekly injections. Wegovy also has daily tablets. Comparing only “two weekly jabs” misses part of the choice. [4][5]

What SURMOUNT-5 found

SURMOUNT-5 was a randomised, open-label, 72-week study in adults with obesity without diabetes. It compared maximum tolerated tirzepatide 10 or 15 mg weekly with semaglutide 1.7 or 2.4 mg weekly. Average weight reduction was 20.2% versus 13.7% in the modified treatment-regimen analysis, a difference of 6.5 percentage points. Eli Lilly funded the study. [1]

This is stronger evidence for those regimens than placing unrelated trials alongside each other. However, the study did not test 7.2 mg semaglutide, daily Wegovy tablets, every lower maintenance dose or people with type 2 diabetes. Its result should stay attached to those boundaries. [1]

“Percentage points” describes subtraction between two percentages. It is clearer here than a claim that one treatment produces a certain percentage “more” weight loss, which uses a different denominator and can sound more dramatic.

Questions to ask of any comparison

Before accepting a chart, identify five things: the population, exact dose and formulation, duration, comparator and analysis method. Then check whether it reports a mean, the proportion reaching a threshold, or a change among people who remained on treatment. These are different outcomes.

A trial average is not a personal target. Nor does the average describe whether someone could tolerate the treatment, obtain repeat supplies or achieve the health outcome they cared about most. A useful consultation connects the study result to the reason treatment is being considered.

For cardiovascular benefit, SELECT tested semaglutide 2.4 mg injection in people with established cardiovascular disease and overweight or obesity, without diabetes. It provides evidence about that population and endpoint; it is not a direct heart-outcome comparison against tirzepatide. [6]

Compare the treatment routines

Mounjaro calculations count four doses per KwikPen. For Wegovy, identify FlexTouch, the separate single-dose device or tablets before comparing prices. Ask about storage, supplies and disposal. [4][7]

For tablets, consider the routine on an ordinary day rather than assuming that oral treatment is automatically simpler. Wegovy tablets have fasting and waiting requirements. A morning routine that works at home may need planning around shift work or other medicines. [8]

Ask each service the same practical questions: who conducts reviews, who responds to side effects, what happens during a supply interruption, and what the full cost includes. Record the answers beside the product rather than comparing prices in isolation.

Side effects and interactions are part of the choice

Both medicines can cause gastrointestinal side effects. Neither should be chosen on a promise that nausea is impossible. The relevant leaflet and your previous experience of treatment should inform the discussion. [9][10]

Tirzepatide has specific advice for users of oral contraception: additional barrier protection or a suitable non-oral method is needed during the periods after starting and increasing a dose described by the MHRA. Semaglutide has a very rare NAION warning. These differences merit discussion without turning them into an overall safety ranking. [11][12]

Explain which side effects would be particularly difficult for your work, caring duties or eating routine. Ask what the prescriber would do if those problems occurred. A practical response plan is more informative than reassurance that most people manage well.

Licence, funding and follow-up

NICE guidance and NHS commissioning arrangements do not simply reproduce the broader product licences. England's tirzepatide rollout is phased, and local services determine access within the relevant arrangements. [13][14]

Ask what a proposed switch aims to solve. Bring dose history, symptoms and goals. Do not overlap treatments or calculate a switching dose yourself; obtain a prescriber-led plan. [15]

Questions and answers