Guide

Tirzepatide vs semaglutide

One trial put them head to head. The result was not close — but the cheaper drug still wins for some people.

Updated 2026-09-18 · Prices verified independently

Why you can trust this: we take payment from one company on this page — Coreage Rx — when a reader signs up through our link. It does not change the prices we print or the rubric we score against, both of which are published in full on how we rate. Read our full disclosure.

These two drugs get talked about as though they were interchangeable. They are not, and there is a head-to-head trial that settles the weight-loss question fairly clearly.

SURMOUNT-5 compared them directly. 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). That is a meaningful gap, and it is the main reason tirzepatide costs more almost everywhere you look.

What each one is

Tirzepatide

A single weekly injection that activates two gut hormone receptors, GIP and GLP-1, rather than one. Sold as Zepbound and Mounjaro by Eli Lilly. 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.

Doses step up through 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg.

Semaglutide

A weekly injection that activates the GLP-1 receptor, slowing stomach emptying and reducing appetite signalling. Sold as Wegovy and Ozempic by Novo Nordisk. In STEP-1, adults on 2.4 mg lost an average of about 14.9% of body weight over 68 weeks.

Doses step up through 0.25 mg, 0.5 mg, 1 mg, 1.7 mg, 2.4 mg.

So why would anyone choose semaglutide?

It is consistently cheaper. Compounded semaglutide runs roughly $99 to $198 a month against $149 to $449 for tirzepatide.
It has been in wide use longer, so there is more real-world experience with it.
Some people tolerate it better, though both carry the same broad side-effect profile.
Insurance is somewhat more likely to have a pathway for branded 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 the argument for a slower titration even when a programme offers a faster one.

What they cost

	Tirzepatide	Semaglutide
Cheapest compounded, all in	$199/mo	$149/mo
Typical compounded	$278–$399/mo	$178–$297/mo
Brand-name self-pay	$299–$499/mo	$199–$349/mo

Our full workings are in the cheapest GLP-1 programmes, and the rankings are in best tirzepatide providers and best semaglutide providers.

Which should you ask for?

If cost is the binding constraint, semaglutide. If you want the largest average weight loss and can afford the difference, tirzepatide. This is a conversation to have with the clinician who will actually be prescribing it — neither drug is right for everyone, and both have contraindications that a questionnaire alone will not catch.