Semaglutide vs Tirzepatide
Two molecules, five brands, and a set of FDA labels that do not say what most articles imply. Here is the mechanism, the label-by-label indication map, the head-to-head trial evidence, and what each one costs.
Semaglutide is a GLP-1 receptor agonist (Ozempic, Wegovy, Rybelsus). Tirzepatide is a dual GIP and GLP-1 receptor agonist (Mounjaro, Zepbound). In SURMOUNT-5, the 72-week head-to-head trial, mean weight change was -20.2% with tirzepatide versus -13.7% with semaglutide. Only Wegovy and Zepbound are approved for weight management; Ozempic, Rybelsus and Mounjaro are approved for type 2 diabetes. This is information, not medical advice.
Sourced to current FDA labeling and peer-reviewed trials · 14 min read
Semaglutide vs Tirzepatide at a Glance
| Attribute | Semaglutide | Tirzepatide |
|---|---|---|
| Drug class | GLP-1 receptor agonist (single incretin) | Dual GIP + GLP-1 receptor agonist (two incretins) |
| Manufacturer | Novo Nordisk | Eli Lilly |
| Brands | Ozempic, Wegovy, Rybelsus | Mounjaro, Zepbound |
| Type 2 diabetes brand | Ozempic (injection), Rybelsus (tablet) | Mounjaro (injection) |
| Weight-management brand | Wegovy | Zepbound |
| Oral form available | Yes (semaglutide tablets) | No (injection only) |
| Label dose range (weekly injection) | Ozempic 0.25 to 2 mg; Wegovy 0.25 to 2.4 mg, up to 7.2 mg | Mounjaro and Zepbound 2.5 to 15 mg |
| Head-to-head weight trial (SURMOUNT-5, 72 weeks) | -13.7% mean body-weight change | -20.2% mean body-weight change |
| Head-to-head diabetes trial (SURPASS-2, 40 weeks) | -1.86 percentage points A1C (1 mg) | -2.01 to -2.30 percentage points A1C (5 to 15 mg) |
| Boxed warning | Thyroid C-cell tumors in rodents | Thyroid C-cell tumors in rodents |
Mechanism, indication and dose-range rows are read off the current FDA labeling for each brand. Trial rows are group averages from the published SURMOUNT-5 and SURPASS-2 studies, not individual outcomes. Doses are set by a prescriber. For the wider category, see the full list of GLP-1 medications and the complete GLP-1 weight-loss guide.
On the spelling. The drug is tirzepatide. It is very commonly searched as "tirzepitide," "terzepatide" or "tirzepatide vs semaglutide" in either order. All of those point at the same molecule described here. If a seller spells it differently on a label or invoice, treat that as a reason to check what you are actually being sold.
Mechanism: One Incretin Pathway vs Two
The comparison starts with receptors, not brands. Your gut releases incretin hormones after you eat. Two of them matter here: GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide). Both amplify insulin release when glucose is high, and both influence appetite signaling and how quickly the stomach empties.
Semaglutide is a GLP-1 receptor agonist. It is a single-target molecule: it binds the GLP-1 receptor and mimics that one hormone. That mechanism drives the effects the labels describe for both its diabetes and its weight indications, glycemic improvement and reduced energy intake.
Tirzepatide is a dual GIP and GLP-1 receptor agonist. It is a single peptide engineered to activate both receptors. FDA labeling describes tirzepatide as a GIP and GLP-1 receptor agonist, which is the structural difference between the two drugs, and the reason no straight milligram-for-milligram equivalence exists between them.
Two practical consequences follow from that, and they are the ones worth carrying into a clinician conversation:
- The dose numbers are not comparable. Semaglutide injection labels run 0.25 mg to 2.4 mg weekly (with a higher 7.2 mg option on the Wegovy label); tirzepatide labels run 2.5 mg to 15 mg weekly. A larger number on a tirzepatide pen does not mean a larger dose in any clinical sense.
- Response and tolerability can differ per person. Adding GIP activity changes the pharmacology. Group averages from trials say nothing certain about how one individual will respond or what side effects they will have.
Everything downstream, the brands, the trial results, the pricing, is a consequence of this one structural difference plus the commercial choices Novo Nordisk and Eli Lilly made about which indication to pursue under which brand name.
Which Brand Is Which, and What Each Is Actually Approved For
This is where most comparisons get sloppy. Two molecules carry five US brand names, and the FDA-approved indication belongs to the brand, not the molecule. Semaglutide is approved for weight management as Wegovy but not as Ozempic. Tirzepatide is approved for weight management as Zepbound but not as Mounjaro. The indications below are taken from the current prescribing information for each product.
| Brand | Molecule | FDA-approved indication | Weight loss? |
|---|---|---|---|
| Ozempic (injection) | Semaglutide | Type 2 diabetes: adjunct to diet and exercise to improve glycemic control in adults, plus cardiovascular and kidney risk reduction in defined populations | Not approved for weight loss |
| Wegovy (injection and tablet) | Semaglutide | Chronic weight management in adults and, for the injection, patients 12 and older; reduction of major adverse cardiovascular events in adults with established CV disease and obesity or overweight; the injection also carries an accelerated approval in noncirrhotic MASH with F2-F3 fibrosis | Approved |
| Rybelsus (tablet) | Oral semaglutide | Type 2 diabetes: adjunct to diet and exercise to improve glycemic control in adults, plus cardiovascular risk reduction in adults with type 2 diabetes | Not approved for weight loss |
| Mounjaro (injection) | Tirzepatide | Type 2 diabetes: adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years and older | Not approved for weight loss |
| Zepbound (injection) | Tirzepatide | Chronic weight reduction and long-term maintenance in adults with obesity, or overweight with at least one weight-related comorbidity; also moderate to severe obstructive sleep apnea in adults with obesity | Approved |
Off-label prescribing, named plainly
Ozempic, Rybelsus and Mounjaro are approved to improve glycemic control in type 2 diabetes. None of the three is approved for weight loss. Prescribing any of them for weight reduction is off-label prescribing, which is legal for a licensed clinician but is not the same as an FDA-approved use, and it frequently changes what insurance will cover. If weight management is the goal, the on-label options are Wegovy and Zepbound. See our Wegovy vs Ozempic comparison for the same-molecule version of this problem on the semaglutide side, and Mounjaro vs Ozempic for the diabetes-brand comparison.
Two label details deserve their own line, because they are unique to one side of this comparison:
- Zepbound carries an obstructive sleep apnea indication. Tirzepatide was the first medication FDA-approved to treat moderate to severe obstructive sleep apnea in adults with obesity. No semaglutide product carries that indication.
- Semaglutide is the only one of the two available as a tablet. Oral semaglutide tablets are marketed for type 2 diabetes under the Rybelsus name, and the Wegovy label now covers a tablet as well as the injection. Tirzepatide is injection only. If swallowing a pill instead of injecting is the deciding factor, that is a semaglutide-only path today. Our GLP-1 pill guide covers the oral options in detail.
Head-to-Head Evidence: What the Trials Actually Compared
Most drug comparisons are cross-trial guesswork, comparing a number from one study against a number from a different study with different patients. Semaglutide and tirzepatide are an unusual case: they have been compared directly, in two randomized trials, one for obesity and one for type 2 diabetes.
SURMOUNT-5: obesity, 72 weeks
Published in the New England Journal of Medicine in 2025, SURMOUNT-5 randomized 751 adults with obesity and without type 2 diabetes to tirzepatide (maximum tolerated dose of 10 or 15 mg weekly) or semaglutide (maximum tolerated dose of 1.7 or 2.4 mg weekly) for 72 weeks.
- Mean percentage change in body weight: -20.2% with tirzepatide (95% CI, -21.4 to -19.1) versus -13.7% with semaglutide (95% CI, -14.9 to -12.6), P<0.001.
- The most common adverse events in both groups were gastrointestinal, mostly mild to moderate, and occurred primarily during dose escalation.
SURPASS-2: type 2 diabetes, 40 weeks
Published in the New England Journal of Medicine in 2021, SURPASS-2 was an open-label 40-week trial that randomized 1,879 adults with type 2 diabetes to tirzepatide 5, 10 or 15 mg weekly or semaglutide 1 mg weekly.
- A1C reduction: -2.01, -2.24 and -2.30 percentage points for tirzepatide 5, 10 and 15 mg respectively, versus -1.86 percentage points for semaglutide 1 mg.
- Body-weight reduction was greater with tirzepatide, with least-squares mean estimated treatment differences of -1.9 kg, -3.6 kg and -5.5 kg versus semaglutide 1 mg.
Read these numbers correctly
- They are group averages. A trial mean is not a prediction for any individual, and both trials paired the drug with diet and activity changes. No result is guaranteed.
- SURMOUNT-5 used the weight-management brands. The doses studied correspond to Zepbound and Wegovy, not to Mounjaro and Ozempic.
- SURPASS-2 compared semaglutide at 1 mg, the diabetes dose, not the higher weight-management doses. That comparison is about glycemic control in type 2 diabetes.
- Bigger average is not automatically better for you. Tolerability, coverage, comorbidities, the pill-versus-injection question and the sleep-apnea indication all move the decision. That decision belongs to a prescriber.
Dosing: What the FDA Labels Specify
The table below reports the titration schedules printed in the current FDA prescribing information for each brand. It is educational reporting of published labeling, nothing more. A prescriber determines your dose, your escalation pace, and whether you escalate at all. Do not start, change, combine or convert doses on your own.
| Product | Label starting dose | Label escalation | Label maximum |
|---|---|---|---|
| Ozempic (semaglutide) | 0.25 mg once weekly for 4 weeks | 0.5 mg, then 1 mg, then 2 mg, each after at least 4 weeks at the prior dose | 2 mg once weekly |
| Wegovy injection (semaglutide) | 0.25 mg once weekly, weeks 1 to 4 | 0.5 mg (weeks 5 to 8), 1 mg (weeks 9 to 12), 1.7 mg (weeks 13 to 16), then maintenance from week 17 | Maintenance 1.7 or 2.4 mg; label permits 7.2 mg once weekly for weight reduction in adults tolerating 2.4 mg for at least 4 weeks |
| Rybelsus (oral semaglutide, type 2 diabetes) | 3 mg once daily, days 1 to 30 | 7 mg once daily from day 31; may increase to 14 mg from day 61 if more glycemic control is needed | 14 mg once daily |
| Mounjaro (tirzepatide) | 2.5 mg once weekly for 4 weeks | Increase to 5 mg, then in 2.5 mg increments after at least 4 weeks at the current dose | 15 mg once weekly in adults; 10 mg in patients 10 years and older |
| Zepbound (tirzepatide) | 2.5 mg once weekly for 4 weeks | Increase to 5 mg, then in 2.5 mg increments after at least 4 weeks at the current dose | 15 mg once weekly (maintenance 5, 10 or 15 mg for weight; 10 or 15 mg for obstructive sleep apnea) |
There is no conversion table between these two drugs. Semaglutide milligrams and tirzepatide milligrams are not interchangeable units, and this guide will not tell you how to switch between them. Switching, restarting after a gap, splitting a vial, or holding a dose are all clinical decisions. Bring the question to the prescriber. For deeper label detail, see our semaglutide dosing guide and tirzepatide dosing guide.
Side Effects and Warnings: Mostly Shared
Since both drugs act on the GLP-1 receptor, their most common adverse reactions overlap almost completely. The labels for both list gastrointestinal effects at the top: nausea, diarrhea, vomiting, constipation, decreased appetite, abdominal pain and dyspepsia, generally most noticeable during dose escalation. The Mounjaro label reports these as occurring in at least 5% of patients, with nausea up to 18% and diarrhea up to 17%.
Both molecules carry the same FDA boxed warning: in rodents, they caused thyroid C-cell tumors at clinically relevant exposures, and it is unknown whether they cause thyroid C-cell tumors, including medullary thyroid carcinoma, in humans. Both are contraindicated in people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. Both labels also describe rarer serious risks including pancreatitis, gallbladder disease, and, when combined with insulin or a sulfonylurea, hypoglycemia.
A shared consideration that neither label frames as a side effect: weight lost on either drug is not exclusively fat. Preserving lean mass through protein intake and resistance training is part of a serious plan on either molecule, which we cover in GLP-1 and muscle loss.
Brand-specific detail lives in the dedicated guides: tirzepatide side effects and Ozempic side effects.
Cost: Semaglutide vs Tirzepatide
Neither molecule is structurally cheaper than the other. Four things set what you actually pay, and the drug class is not one of them:
- The brand you are prescribed. List prices differ by product. Novo Nordisk publishes a list price (wholesale acquisition cost) of $1,349.02 per package for Wegovy and $1,027.51 per package for Ozempic. Almost nobody pays list. Eli Lilly publishes its own list and self-pay pricing for Mounjaro and Zepbound on its product and LillyDirect sites; check the current figures there rather than trusting a number in an article.
- The purchase route. A manufacturer self-pay program, a retail pharmacy with a savings card, a telehealth program, and a local weight-loss clinic are four different prices for the same prescription.
- What the monthly fee includes. A clinic program that bundles the medication, visits and labs is not comparable to a membership fee that bills the drug separately, even when the headline numbers look alike.
- Coverage. Plans routinely cover a GLP-1 for type 2 diabetes and deny the same molecule for weight management, or require prior authorization. Coverage, not chemistry, is usually the largest single swing in your out-of-pocket cost.
Price both molecules before you decide
We track cash-pay program prices quoted from clinics' own websites and dated, so the comparison is like-for-like rather than anecdote-for-anecdote:
One honest framing on value. If SURMOUNT-5 is your reason for preferring tirzepatide, note that the trial compared the on-label weight-management products. Chasing that result through a cheaper off-label or non-FDA-approved supply is not the same intervention that produced the number.
Compounded Semaglutide and Tirzepatide Are Not FDA-Approved
A large share of the cheap semaglutide and tirzepatide advertised online is compounded, not brand product. This distinction is not a technicality:
- Compounded drugs are not FDA-approved. FDA does not review compounded versions of semaglutide or tirzepatide for safety, effectiveness or quality before they are sold.
- FDA has warned specifically about dosing errors with compounded GLP-1 products. The agency has received reports of adverse events tied to patients measuring and self-administering doses from multi-dose vials and syringes, including overdoses of many times the intended amount, and has flagged unapproved GLP-1 drugs sold for weight loss as a safety concern.
- Product identity is not guaranteed. Salt forms, research-use-only peptides, and products bought from unregulated sellers are not the same as the studied medicine, whatever the label says.
None of this means every compounding pharmacy is illegitimate. It means a compounded product is a different risk category from the brand product a trial studied, and it should be discussed with the prescriber rather than assumed equivalent. Our compounded semaglutide guide covers the regulatory picture in full.
Retatrutide vs Tirzepatide: Investigational, Not Approved
"Retatrutide vs tirzepatide" is now a heavily searched comparison, so here is the honest version of it.
Retatrutide is an investigational drug. It is not FDA-approved for any use. It cannot be legally prescribed or dispensed as an approved medicine in the United States, it has no FDA label, and it has no approved indication for weight loss, diabetes or anything else. Anything sold as retatrutide today, including "research use only" peptide vials, is outside the FDA-approval system entirely, with no assurance of identity, purity, sterility or dose.
What is known comes from clinical research. Mechanistically, retatrutide goes one receptor further than tirzepatide: it is an agonist of the GIP, GLP-1 and glucagon receptors, a triple agonist, versus tirzepatide's dual GIP and GLP-1 action. In a phase 2 trial published in the New England Journal of Medicine in 2023, 338 adults with obesity were randomized for 48 weeks; mean body-weight change at 48 weeks was -24.2% at the 12 mg dose versus -2.1% with placebo, with dose-dependent results across the lower dose groups.
A phase 3 program is underway, including TRIUMPH-1, a completed placebo-controlled trial of about 2,335 participants without type 2 diabetes, and a registered phase 3 trial comparing retatrutide directly against tirzepatide in adults with obesity, listed on ClinicalTrials.gov as active and not recruiting.
What this means practically
- A phase 2 percentage cannot be compared to tirzepatide's phase 3 numbers as if the two were equivalent evidence. Different trials, different populations, different duration.
- The direct comparison people are searching for is literally still being run. Until that trial reports, "retatrutide beats tirzepatide" is a claim without head-to-head data behind it.
- The only tirzepatide products you can legally obtain as approved medicines are Mounjaro and Zepbound, on their labeled indications. That is the practical comparison available today.
If a seller offers you retatrutide, the correct response is not price-shopping. It is recognizing that you are being offered an unapproved drug. Bring it up with a licensed clinician before considering it.
Which One Fits Your Situation?
There is no universal winner. These are the honest framings a prescriber conversation usually lands on.
Tirzepatide may be discussed if
- ✓The head-to-head obesity trial average matters to you and you qualify for the on-label product
- ✓You have moderate to severe obstructive sleep apnea with obesity, the one indication only tirzepatide carries
- ✓Your coverage or self-pay route lands cheaper on the Lilly side
Semaglutide may be discussed if
- ✓You want or need an oral option, which exists only on the semaglutide side
- ✓You need the cardiovascular or MASH indications carried on the Wegovy label
- ✓It is what your plan covers, or you are already established and tolerating it
Bring these four questions to the appointment:
- Is my diagnosis type 2 diabetes or obesity, and which brand is on-label for it?
- What does my plan cover, and does it require prior authorization?
- What is the total cash price if coverage is denied, including labs and visits?
- What is the plan for tolerability during escalation, and for the long term?
To see what cash-pay programs charge and who prescribes what near you, start at the GLP-1 and weight-loss clinic directory.
Frequently Asked Questions
What is the difference between semaglutide and tirzepatide?▼
Semaglutide is a GLP-1 receptor agonist: it mimics one gut incretin hormone. Tirzepatide is a dual GIP and GLP-1 receptor agonist: one molecule that activates two incretin pathways. Semaglutide is made by Novo Nordisk and sold as Ozempic, Wegovy and Rybelsus; tirzepatide is made by Eli Lilly and sold as Mounjaro and Zepbound. Both are once-weekly subcutaneous injections, and semaglutide is also available as a tablet. The FDA-approved use depends on the brand, not the molecule.
Is tirzepatide better than semaglutide for weight loss?▼
In SURMOUNT-5, the head-to-head trial published in the New England Journal of Medicine, 751 adults with obesity and without type 2 diabetes were randomized for 72 weeks. Mean weight change was -20.2% with tirzepatide (10 or 15 mg) versus -13.7% with semaglutide (1.7 or 2.4 mg). Those are group averages under trial conditions, not a promise of an individual result, and the trial used the weight-management brands Zepbound and Wegovy. Which drug is appropriate for you is a decision for a licensed prescriber.
Which brands are semaglutide and which are tirzepatide?▼
Semaglutide brands: Ozempic (injection, approved for type 2 diabetes), Wegovy (approved for chronic weight management and cardiovascular risk reduction), and Rybelsus (oral tablet, approved for type 2 diabetes). Tirzepatide brands: Mounjaro (approved for type 2 diabetes) and Zepbound (approved for chronic weight management and for moderate to severe obstructive sleep apnea in adults with obesity). Using a diabetes-labeled brand for weight loss is off-label prescribing.
Is semaglutide or tirzepatide cheaper without insurance?▼
Neither molecule is reliably cheaper than the other, because your cash price is set by the brand, the dose, and the purchase route rather than by the drug class. Novo Nordisk publishes a list price of $1,349.02 per package for Wegovy and $1,027.51 per package for Ozempic, and both manufacturers run direct self-pay programs that price well below list. Clinic and telehealth programs are priced separately again. Compare the verified per-clinic monthly medians in our semaglutide cost and tirzepatide cost guides, then confirm the current number with the pharmacy or clinic.
Can you switch from semaglutide to tirzepatide?▼
Switching is a prescriber decision, and there is no milligram-to-milligram conversion between the two. They are different molecules with different receptor targets and different label titration schedules: the semaglutide injection labels start at 0.25 mg weekly, while the tirzepatide labels start at 2.5 mg weekly. Do not convert, stack or self-adjust doses. Ask the prescribing clinician how a transition should be handled.
Do semaglutide and tirzepatide have different side effects?▼
The profiles overlap heavily. Both labels list gastrointestinal reactions as the most common: nausea, diarrhea, vomiting, constipation, decreased appetite and abdominal pain, mostly during dose escalation. The Mounjaro label reports nausea up to 18% and diarrhea up to 17%. Both molecules carry the FDA boxed warning for thyroid C-cell tumors seen in rodents, and both are contraindicated in people with a personal or family history of medullary thyroid carcinoma or MEN 2. Review your own risk with a clinician.
How does retatrutide compare to tirzepatide?▼
Retatrutide is investigational and not FDA-approved, so no honest comparison to tirzepatide as a treatment is possible yet. It is a triple agonist of the GIP, GLP-1 and glucagon receptors, one more target than tirzepatide. In a 338-person phase 2 trial published in the New England Journal of Medicine, mean weight change at 48 weeks was -24.2% at the 12 mg dose versus -2.1% with placebo. A phase 3 head-to-head trial of retatrutide against tirzepatide in adults with obesity is registered on ClinicalTrials.gov and listed as active, not recruiting. Any retatrutide sold today is not an FDA-approved product.
Compare Cash-Pay GLP-1 Programs
See what clinics and telehealth programs actually charge for semaglutide and tirzepatide, with every price quoted from the source and dated.
Explore Weight-Loss OptionsRelated Guides
Sources & References
- • DailyMed (FDA labeling) — Ozempic (semaglutide) injection: indications, titration, boxed warning
- • DailyMed (FDA labeling) — Wegovy (semaglutide) injection and tablet: indications, titration, boxed warning
- • DailyMed (FDA labeling) — Rybelsus and oral semaglutide tablets: type 2 diabetes indication
- • DailyMed (FDA labeling) — Mounjaro (tirzepatide): indication, titration, adverse reactions
- • DailyMed (FDA labeling) — Zepbound (tirzepatide): weight and obstructive sleep apnea indications
- • FDA — Mounjaro (tirzepatide) approved prescribing information (PDF)
- • FDA — Zepbound (tirzepatide) approved prescribing information (PDF)
- • FDA — first medication approved for obstructive sleep apnea
- • SURMOUNT-5 — Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (N Engl J Med, 2025)
- • SURPASS-2 — Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (N Engl J Med, 2021)
- • Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial (N Engl J Med, 2023)
- • ClinicalTrials.gov — phase 3 retatrutide compared with tirzepatide in adults with obesity (NCT06662383)
- • ClinicalTrials.gov — TRIUMPH-1 phase 3 retatrutide trial (NCT05929066)
- • FDA — concerns with unapproved GLP-1 drugs used for weight loss (including compounded dosing errors)
- • Novo Nordisk — published list price (WAC) for Wegovy
- • Novo Nordisk — published list price (WAC) for Ozempic
- • Zepbound (Eli Lilly) — official product site
- • LillyDirect — Eli Lilly direct self-pay pharmacy
Educational Disclaimer
This guide is published for educational purposes only. It is not medical advice, and it is not a substitute for diagnosis, treatment, or a prescription from a licensed clinician. Dosing information here is a report of what published FDA labeling specifies; your prescriber determines whether a medication is appropriate, at what dose, and on what schedule. Never start, stop, change, combine, or convert a prescription on your own. Trial results are group averages under study conditions and are not a prediction or guarantee of any individual result. Compounded semaglutide and compounded tirzepatide are not FDA-approved, and retatrutide is investigational and not FDA-approved for any use. Prices are gathered from published sources, change without notice, and must be confirmed with the pharmacy, manufacturer, or clinic. Consult a licensed clinician before making any decision about these medications.
Medical disclaimer: This page is general information, not medical advice. Listings are aggregated from public sources and prices are estimates that may be out of date — confirm current pricing, services, and provider credentials directly with each clinic. Talk to a licensed clinician before starting any medication or treatment.
Affiliate disclosure: VitalityScout may earn a commission from some links, at no additional cost to you. This never affects which providers we list or how we describe them.
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