Guide
Semaglutide vs Tirzepatide
The two medications behind almost every GLP-1 programme sold online. They are not interchangeable: one acts on a single incretin pathway, the other on two, and in the only head-to-head trial the difference showed up in the results.
| Semaglutide | Tirzepatide | |
|---|---|---|
| How it works | GLP-1 receptor agonist — mimics one incretin hormone | Dual GIP and GLP-1 receptor agonist — acts on two incretin pathways |
| Brand names | Ozempic and Rybelsus (type 2 diabetes), Wegovy (weight management) | Mounjaro (type 2 diabetes), Zepbound (weight management) |
| Manufacturer | Novo Nordisk | Eli Lilly |
| Headline trial result | STEP 1: mean 14.9% body weight loss at 68 weeks on 2.4 mg weekly, vs 2.4% placebo | SURMOUNT-1: mean 20.9% at 72 weeks on 15 mg weekly, vs 3.1% placebo |
| Lean mass share of loss | STEP 1 substudy: roughly 45% of weight lost was lean tissue | SURMOUNT-1 substudy: roughly 25% |
| Oral option | Yes — Rybelsus, an approved tablet, with strict dosing conditions | No approved oral tirzepatide exists in any form |
| Room-temperature window | Ozempic up to 56 days after first use; Wegovy up to 28 days at or below 86°F | Up to 21 days at or below 86°F, and it cannot go back in the fridge afterwards |
| Typical compounded price | Commonly $99–$159/month from the providers we price | Commonly $125–$239/month — consistently more expensive |
The Head-To-Head Trial
Cross-trial comparison is a weak form of evidence — STEP 1 and SURMOUNT-1 ran at different times with different populations, and lining up 14.9% against 20.9% overstates how confidently you can rank them. What settles it more directly is SURMOUNT-5, a 72-week head-to-head phase IIIb trial that compared tirzepatide with semaglutide in the same study. It found greater weight loss and greater waist circumference reduction with tirzepatide.
So the direction of the answer is reasonably settled: on average, tirzepatide produces more weight loss than semaglutide. That does not make it the right choice for any particular person — averages are not predictions, tolerability varies, and the cheaper, more widely available drug that you actually stay on beats the more effective one you stop taking.
These figures describe the approved branded products
Every number above comes from trials of FDA-approved medication at approved doses. Most of what is sold online is compounded, which is not FDA-approved, has not been through equivalent trials, and shares an active ingredient rather than an evidence base. Microdosed protocols in particular deliver well below the trial doses and should not be expected to produce trial results.
Which Should You Ask About?
Reasons to lean semaglutide
- ✓Consistently cheaper — often $30–$100 a month less
- ✓An approved oral form exists (Rybelsus) if injections are the barrier
- ✓Longer real-world track record and more prescriber familiarity
- ✓More forgiving storage — Ozempic tolerates 56 days at room temperature after first use
Reasons to lean tirzepatide
- ✓Greater average weight loss, including in a direct head-to-head trial
- ✓A better lean-mass profile in the published body-composition substudies
- ✓Some people who plateau or do not respond on semaglutide respond to it
- —But it costs more, and there is no approved oral version
This is a conversation to have with the clinician who prescribes for you, not a decision to make from a table. Both drugs share the same contraindications and the same common side effects, and the practical determinants — cost, what your insurance covers, whether you tolerate it, and which one you can reliably get hold of — matter more for most people than the difference in trial averages. See verified semaglutide pricing and verified tirzepatide pricing.
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Medical Disclaimer: This page is for informational purposes only and does not constitute medical advice. Always consult a licensed healthcare provider before starting or changing any treatment. Compounded medications are not FDA-approved, are not evaluated by the FDA for safety, effectiveness or quality, and are not equivalent to the branded drug beyond sharing an active ingredient. GLP-1 medications commonly cause nausea, vomiting, diarrhoea and constipation, and carry risks including pancreatitis, gallbladder disease and kidney injury; they are contraindicated in people with a personal or family history of medullary thyroid carcinoma or MEN 2, and should not be used in pregnancy, when trying to conceive, or while breastfeeding. Prescribing is subject to clinician approval and is never guaranteed. Individual results vary and no outcome is promised.