Tirzepatide vs Semaglutide

The structural difference

Semaglutide is a GLP-1 receptor agonist. Tirzepatide is a dual agonist at the GIP and GLP-1 receptors. Semaglutide acts at one receptor; tirzepatide adds a second. Tirzepatide was engineered from the native GIP sequence rather than from GLP-1, which is why it is described as GIP-based with added GLP-1 activity rather than the other way round.

Both are peptides, both are given weekly in their licensed presentations, and both belong to the same pharmacological family. That is why the comparison is asked so often, and the family resemblance is genuine.

The head-to-head trial

Most comparisons in this market have to be assembled from separate studies with different populations and different endpoints, which makes them weak. This one does not.

SURMOUNT-5 was a phase 3b trial that compared tirzepatide directly against semaglutide, published in the New England Journal of Medicine (doi:10.1056/NEJMoa2416394). A head-to-head design removes the largest source of error in cross-trial comparison: the two arms are the same people, enrolled under the same protocol, measured the same way.

We are not going to restate its numbers as a result you should expect, because that is the step where a trial finding turns into a use claim. The paper is linked and open to read. What we will say is that a randomised head-to-head comparison is a stronger form of evidence than two separate trials read side by side, and that it exists for this pair and for very few others.

Tirzepatide's own reference trial is SURMOUNT-1, phase 3, randomised, double-blind and placebo-controlled across 119 sites in nine countries (doi:10.1056/NEJMoa2206038).

Side by side

Those brand names are licensed medicines. They are listed so the vocabulary lines up, because a reader searching one of them is usually searching for the compound inside it and does not always know the two are different things.

Brand name, compound name, and why it matters

Half the confusion in this comparison is vocabulary. Mounjaro and Zepbound are brand names for tirzepatide. Ozempic, Wegovy and Rybelsus are brand names for semaglutide. A brand name identifies a licensed finished product: a specific manufacturer, a specific formulation, a specific presentation, a specific authorised indication. A compound name identifies a molecule and nothing else.

That is why "is tirzepatide the same as Mounjaro" has an awkward answer. The molecule is the same molecule. The product is not the same product, and the authorisation attaches to the product. What we supply is the compound as an unlicensed research material — see are peptides legal in the UK for how those categories work, and retatrutide vs Mounjaro for the same point made against a compound with no licensed form at all.

What we supply, and what we do not

We supply tirzepatide as an unlicensed research compound, in 10mg, 20mg, 30mg and 40mg vials, in 20mg and 40mg pens, in a starter kit and in a blend with cagrilintide.

Semaglutide is not in our range. Nothing on this page should be read as an offer to supply it, and we do not supply any licensed medicine under any name.

If the comparison you actually want is against a three-receptor compound, that is retatrutide vs tirzepatide.

Reading a specification instead of a label

A licensed medicine carries a Summary of Product Characteristics and a patient information leaflet, both published and maintained by the regulator, both describing an authorised use. An unlicensed research compound carries an analytical specification: the compound name, the quantity, and the purity determined by HPLC.

Those two documents answer different questions, and treating one as though it were the other is the most common error made when comparing a research compound to a branded medicine. The specification tells you what is in the vial. It does not tell you what to do with it, and it is not a shorter version of a leaflet.

Supply note. Peptiq supplies research compounds for laboratory research use only. We are not a pharmacy and we do not supply licensed medicines. Where a licensed medicine is named on this page it is named to draw a distinction, not because we sell it, and nothing here is guidance on use.