Tirzepatide vs semaglutide
One works better. The other is cheaper. Here is the actual size of both gaps.
Updated 2026-09-18 · every price checked by hand
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Two questions decide this, and they pull in opposite directions: which one works better, and which one costs less.
On results, it is settled by a head-to-head trial. SURMOUNT-5 compared the two drugs directly. Participants on tirzepatide lost an average of 50.3 lb (22.8 kg); those on semaglutide lost 33.1 lb (15.0 kg). On cost, semaglutide wins almost everywhere: the cheapest compounded semaglutide runs about $1,188 a year against roughly $1,788 to $2,388 for tirzepatide.
What the trials found
Tirzepatide. In SURMOUNT-1, adults with obesity lost an average of 19.5% of body weight on 10 mg and 20.9% on 15 mg over 72 weeks.
Semaglutide. In STEP-1, adults on 2.4 mg lost an average of about 14.9% of body weight over 68 weeks.
Those are averages from controlled trials with structured support behind them. Real-world results vary more, and people who stop taking either drug generally regain a substantial share of the weight.
How they work
Tirzepatide — A single weekly injection that activates two gut hormone receptors, GIP and GLP-1, rather than one. Sold as Zepbound and Mounjaro.
Semaglutide — A weekly injection that activates the GLP-1 receptor, slowing stomach emptying and reducing appetite signalling. Sold as Wegovy and Ozempic.
What each costs
| Tirzepatide | Semaglutide | |
|---|---|---|
| Cheapest compounded, per year | $1,788–$2,388 | $1,188–$1,788 |
| Typical compounded, per year | $2,592–$4,788 | $1,812–$3,564 |
| Brand-name self-pay, per month | $299–$499 | $199–$349 |
Full tables: cheapest tirzepatide and cheapest semaglutide.
Side effects
Tirzepatide: Nausea, diarrhoea, constipation and reflux, concentrated in the weeks after each dose increase.
Semaglutide: Nausea, vomiting, diarrhoea and constipation, usually worst in the first weeks and after dose increases.
Both are worst in the fortnight after a dose increase, which is a good argument for a slower titration even where a programme offers a faster one.
So which?
If the budget is tight, semaglutide — it is cheaper everywhere and still produced roughly 15% average weight loss in its trials. If you can afford the difference and want the larger average result, tirzepatide. Either way this is a conversation for the clinician who will be prescribing it; both drugs have contraindications a questionnaire will not catch.