Semaglutide vs. Tirzepatide
These are the two medications that dominate the weight-loss market, and the choice between them is usually framed as "tirzepatide works better." That is broadly supported by the trial data — but it is not the whole answer, and it is not always the right answer for an individual patient. Cost, side-effect tolerance, cardiovascular history and what your insurance will cover all shift the calculation.
The short version
| Semaglutide | Tirzepatide | |
|---|---|---|
| Brand names | Ozempic, Wegovy, Rybelsus | Mounjaro, Zepbound |
| Mechanism | GLP-1 receptor agonist | Dual GIP and GLP-1 receptor agonist |
| Dosing | Once weekly, 0.25 mg → 2.4 mg | Once weekly, 2.5 mg → 15 mg |
| Average trial weight loss | ≈15% at 2.4 mg over 68 weeks (STEP 1) | ≈21% at 15 mg over 72 weeks (SURMOUNT-1) |
| Cardiovascular outcomes data | Strong — SELECT trial showed reduced major adverse cardiovascular events | Growing, but a smaller outcomes evidence base to date |
| Cheapest FDA-approved route | $149/mo pill, $199/mo pen (NovoCare Pharmacy) | $299/mo at 2.5 mg (LillyDirect) |
| Typical compounded price | $70–$299/mo | $100–$545/mo |
| Oral version | Yes — Rybelsus and the Wegovy pill | No FDA-approved oral form |
They work differently, not just at different strengths
Semaglutide is a GLP-1 receptor agonist. It mimics glucagon-like peptide-1, a gut hormone released after eating that stimulates insulin secretion, suppresses glucagon, slows gastric emptying and signals satiety to the brain. Semaglutide is engineered to resist the enzymatic breakdown that limits natural GLP-1, so a single injection lasts about a week.
Tirzepatide does the same thing at the GLP-1 receptor, but it also activates the GIP (glucose-dependent insulinotropic polypeptide) receptor. GIP is a second incretin hormone, and adding its activation appears to improve both glycemic control and weight loss beyond what GLP-1 agonism achieves alone. That dual mechanism is the reason tirzepatide tends to outperform in head-to-head comparisons — it is not simply a stronger version of the same drug.
Read the individual guides for more depth on each: the semaglutide guide and the tirzepatide guide.
What the trials actually showed
In STEP 1, adults without diabetes taking semaglutide 2.4 mg weekly for 68 weeks lost roughly 15% of body weight on average, against about 2.4% on placebo. In SURMOUNT-1, adults taking tirzepatide for 72 weeks lost roughly 15% at the 5 mg dose, 19.5% at 10 mg and 20.9% at 15 mg, against about 3.1% on placebo.
Those are separate trials with different populations, so comparing them directly is imperfect. The SURMOUNT-5 trial addressed that by testing the two head to head over 72 weeks, and tirzepatide produced substantially greater average weight loss than semaglutide. That is the strongest evidence available on the efficacy question, and it favours tirzepatide.
But semaglutide has something tirzepatide does not yet match: the SELECT trial, which showed that semaglutide 2.4 mg reduced major adverse cardiovascular events in people with established cardiovascular disease and overweight or obesity who did not have diabetes. If you have cardiovascular disease, that outcomes evidence may matter more to your prescriber than a few percentage points of additional weight loss.
Averages are not predictions. Trial results describe group means. Individual response to both medications varies widely — some people lose more on semaglutide than they would have on tirzepatide, and some tolerate one far better than the other. Your prescriber's judgment about your history matters more than the headline percentage.
Side effects are broadly similar
Both medications share the same dominant side-effect profile, which is gastrointestinal: nausea, vomiting, diarrhea, constipation and abdominal discomfort. These are most common during titration and often ease as the body adapts. Both carry a boxed warning about thyroid C-cell tumors observed in rodent studies, and both are contraindicated in people with a personal or family history of medullary thyroid carcinoma or MEN 2 syndrome.
Serious but less common risks for both include pancreatitis, gallbladder disease, kidney problems related to dehydration from vomiting or diarrhea, and diabetic retinopathy complications in people with type 2 diabetes. Neither is appropriate during pregnancy.
Practically, the titration schedules differ enough to matter. Because tirzepatide steps from 2.5 mg to 15 mg — a sixfold range — patients who struggle with GI effects sometimes find they can settle at an effective intermediate dose. Our guide to managing GLP-1 side effects covers practical strategies for both.
Cost is where the choice often gets decided
Semaglutide is currently the cheaper molecule at almost every level. Novo Nordisk sells FDA-approved Wegovy and Ozempic direct through NovoCare Pharmacy from $149/month for the pill and $199/month for the pen. Eli Lilly sells Zepbound through LillyDirect from $299/month, rising to $449 at 7.5 mg and above.
The compounded market follows the same pattern. Compounded semaglutide runs roughly $70–$299/month across the providers we track; compounded tirzepatide runs roughly $100–$545. The gap widens as you titrate, because most compounded programs price by milligrams dispensed — which is why flat-price programs matter more for tirzepatide than for semaglutide.
Roughly speaking: if budget is the binding constraint, semaglutide gives you more medication per dollar. If maximum weight loss is the priority and you can absorb the cost, the trial data favours tirzepatide. See the full cost guide for the arithmetic.
Which should you ask about?
- Consider semaglutide if…
- Cost is a real constraint; you have established cardiovascular disease and want the medication with the strongest outcomes data; you want an oral option; or you want the cheapest route to an FDA-approved product.
- Consider tirzepatide if…
- Maximum weight reduction is the priority; you have a large amount of weight to lose; you have already tried semaglutide with disappointing results; or you have type 2 diabetes and want the additional glycemic benefit of dual incretin action.
- Neither is right if…
- You have a personal or family history of medullary thyroid carcinoma or MEN 2 syndrome, you are pregnant or planning pregnancy, or you have a history of severe pancreatitis. See our eligibility guide.
Frequently asked questions
Is tirzepatide just a stronger semaglutide?
No. Tirzepatide activates both the GIP and GLP-1 receptors, while semaglutide activates only GLP-1. The dose numbers are also on completely different scales — 15 mg of tirzepatide is not comparable to 15 mg of semaglutide.
Can I switch between them?
Yes, and it is common. Because the dosing scales differ, you generally restart titration on the new medication rather than converting your dose across. This should be managed by your prescriber.
Do compounded versions work the same way?
Compounded semaglutide and tirzepatide contain the same active molecules, but they are not FDA-approved finished drug products and the FDA does not review them for safety, effectiveness or quality. Compounded formulations frequently add ingredients such as B12 or glycine that are not in the approved products, and the clinical trial results above were generated using the approved medications. See compounded vs. brand-name.
Will I regain the weight if I stop?
Weight regain after stopping is well documented for both medications. Obesity is treated as a chronic condition, and both drugs are generally intended for long-term use rather than a short course. This is worth discussing with your prescriber before you start, because it shapes the real long-run cost.
Where to go next
Medical disclaimer
This article is general information, not medical advice. Clinical trial results describe group averages and do not predict individual outcomes. GLP-1 medications are prescription drugs with serious potential risks, including a boxed warning regarding thyroid C-cell tumors, and are not appropriate for everyone. Talk to a licensed healthcare professional about your own medical history before starting, stopping, or changing treatment. Compounded medications are not FDA-approved and are not reviewed by the FDA for safety, effectiveness, or quality.
Date reviewed: August 3, 2026