Semaglutide and tirzepatide are incretin-based medications available as once-weekly injections. Semaglutide also has daily oral formulations. Semaglutide activates GLP-1 receptors, while tirzepatide activates both GIP and GLP-1 receptors.
In SURMOUNT-5, a 72-week head-to-head trial, tirzepatide produced greater average weight loss than semaglutide.
| Attribute | Semaglutide | Tirzepatide |
|---|---|---|
| Drug class | GLP-1 receptor agonist | Dual GIP and GLP-1 receptor agonist |
| FDA-approved brands | Ozempic®, Wegovy®, Rybelsus® | Mounjaro®, Zepbound® |
| Approved for weight management | Wegovy® | Zepbound® |
| Head-to-head result (SURMOUNT-5, 72 wks) | -13.7% mean body weight | -20.2% mean body weight |
| Discontinued for GI side effects (SURMOUNT-5) | 5.6% | 2.7% |
| Most common side effects | Nausea, vomiting, diarrhea, constipation | Nausea, vomiting, diarrhea, constipation |
| Boxed warning | Thyroid C-cell tumors; MTC/MEN 2 contraindication | Thyroid C-cell tumors; MTC/MEN 2 contraindication |
| Dose escalation | Increases generally at intervals of at least 4 weeks; timing depends on formulation, selected maintenance dose, and tolerability | Increases generally at intervals of at least 4 weeks; timing depends on selected maintenance dose and tolerability |
| Cardiovascular indication | Wegovy®: reduces CV risk in adults with established CVD and obesity/overweight | No equivalent approved CV indication as of Aug 27, 2026 |
| FDA status of compounded products | Compounded products are not FDA-approved | Compounded products are not FDA-approved |
Figures from the FDA-approved products’ prescribing information and the cited trials.
Since the inception of GLP-1s hitting the broader market in 2022, you’ve probably read one or more headlines about “the new weight loss shot” and wondered which name actually applies to you.
Semaglutide and tirzepatide get thrown around like they’re interchangeable, and a lot of marketing out there doesn’t clear that up.
They’re related. They’re not the same. The difference matters for what you can expect from either one, so let’s get into it.
What is semaglutide?
Semaglutide is a GLP-1 receptor agonist, basically a lab-made version of a hormone your gut already releases after you eat to help you feel full. The FDA has approved it under three brand names:
Ozempic®:
available as an injection and, more recently, a tablet. Its approved uses include glycemic control in adults with type 2 diabetes, cardiovascular risk reduction in certain adults with type 2 diabetes and established cardiovascular disease, and kidney-risk reduction in adults with type 2 diabetes and chronic kidney disease (Ozempic prescribing information).
Rybelsus®:
a daily tablet for type 2 diabetes, also approved to reduce the risk of major cardiovascular events in adults with type 2 diabetes who are at high risk for these events (Rybelsus prescribing information).
Wegovy®:
approved for chronic weight management and for reducing cardiovascular risk in adults with established heart disease who also carry obesity or overweight.
The FDA has also approved Wegovy tablets for once-daily oral use for weight reduction and cardiovascular risk reduction in the indicated populations.
Current Wegovy labeling also includes a 7.2 mg injectable dose and a separate adult MASH (metabolic dysfunction-associated steatohepatitis) indication (Wegovy prescribing information).
These products contain semaglutide, but their formulations, doses, administration instructions, and approved indications differ.
What is tirzepatide?
Tirzepatide works on two receptors instead of one, activating both GIP and GLP-1, the dual mechanism that sets it apart from semaglutide. The FDA has approved it under two brand names:
Mounjaro®:
approved, alongside diet and exercise, to improve blood sugar control in adults and children aged 10 years and older with type 2 diabetes (Mounjaro prescribing information).
Zepbound®:
approved for chronic weight management in adults with obesity, or with overweight plus a weight-related condition. It also holds an indication for moderate-to-severe obstructive sleep apnea in adults with obesity, the first drug to earn that specific approval (Zepbound prescribing information).
Both brands contain tirzepatide, although their approved indications and labeling requirements differ.
Eli Lilly first brought tirzepatide to market as Mounjaro in 2022, then followed with Zepbound the next year once the weight-management trials read out.
How semaglutide and tirzepatide work differently
Here’s the single most useful fact in this whole comparison: semaglutide activates one receptor, GLP-1. Tirzepatide activates two, GIP alongside GLP-1.
Both medications reduce calorie intake by affecting appetite, stimulate insulin secretion in a glucose-dependent manner, and delay gastric emptying.
Current labeling notes that GIP activation may further contribute to food-intake regulation, while tirzepatide as a medication has also been shown to increase insulin sensitivity.
The dual-receptor mechanism may contribute to the greater average weight reduction observed with tirzepatide, but the precise reasons for the difference are not fully established.
That head-to-head comparison is what we’ll get into next.
Tirzepatide vs semaglutide for weight loss: what the trial found
SURMOUNT-5 (Aronne LJ et al., NEJM 2025) gave us the first real head-to-head answer, instead of comparing separate trials with different patient groups.
Researchers randomized 751 adults with obesity, or overweight plus a weight-related condition, to either tirzepatide or semaglutide, titrated each person to the highest tolerated dose (10 mg or 15 mg for tirzepatide, 1.7 mg or 2.4 mg for semaglutide), and followed everyone for 72 weeks in this open-label trial (Aronne et al., New England Journal of Medicine, 2025).
Both groups followed the same behavioral support program.
The results:
Tirzepatide (Zepbound):
lost an average of 20.2% of starting body weight
Semaglutide (Wegovy):
lost an average of 13.7% of starting body weight
Waist circumference:
-18.4 cm for tirzepatide vs. -13.0 cm for semaglutide
Statistical significance
p<0.001 The difference between groups was statistically significant.
Real, meaningful numbers, but a single trial can’t capture everything that matters for one person.
A few things worth keeping in mind:
- this trial excluded anyone with diabetes, so it speaks to weight loss specifically, not blood sugar control;
- it measured group averages, and individual results always spread wider than the headline number;
- and genetics, starting weight, and consistency all move the needle for any one person.
Semaglutide vs tirzepatide side effects
Semaglutide and tirzepatide have overlapping gastrointestinal side effects, including nausea, diarrhea, vomiting, and constipation, although the frequency of individual effects may differ. We cover semaglutide side effects in more detail separately.
These effects frequently occur during dose escalation and may lessen over time, although individual experiences vary. In SURMOUNT-5, most adverse events were mild to moderate and occurred mainly during escalation, and a slower titration schedule can help.
In that same trial, GI side effects severe enough to stop treatment happened more often on semaglutide than tirzepatide:
- Semaglutide (Wegovy): 5.6% discontinued
- Tirzepatide (Zepbound): 2.7% discontinued
That’s a real difference in tolerability, not a verdict on which drug is safer overall.
Boxed warning: both products carry boxed warnings concerning thyroid C-cell tumors observed in animal studies and are contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
Several overlapping serious risks also apply to both, including pancreatitis, gallbladder problems, and kidney injury from dehydration. None of this is meant to alarm you, it’s exactly why a LaSara physician reviews your full history before prescribing either one.
Do you lose more muscle on semaglutide or tirzepatide?
Substantial weight reduction commonly includes some loss of lean mass as well as fat mass. That’s normal physiology, not a flaw specific to these drugs. Keep in mind that lean mass measured using DXA is not identical to skeletal muscle.
Separate trials of each medication have measured this:
Wegovy (STEP 1 body-composition substudy):
lean mass made up close to 40% of total weight lost. This came from a substudy, not the full STEP 1 population (Wilding et al., STEP 1 DXA substudy).
Zepbound (SURMOUNT-1 DXA substudy):
approximately 26% of the weight reduction among tirzepatide-treated participants was attributed to lean mass, based on 160 participants with usable measurements.
Those come from different trials with different participants, so they don’t translate into a clean comparison, and SURMOUNT-5 itself didn’t report body composition data for either drug.
A 2026 observational preprint compared lean-mass changes among patients receiving tirzepatide and semaglutide, including analyses based on the degree of weight loss. Because it has not been peer-reviewed, its findings should be treated as preliminary.
Strength training and enough protein remain the best-supported ways to protect lean mass either way.
Semaglutide vs tirzepatide dosing schedules
Every FDA-approved version of these drugs starts low and increases gradually to reduce GI side effects during adjustment. Dose increases generally occur at intervals of at least four weeks; the exact timing depends on the formulation, selected maintenance dose, and tolerability.
For semaglutide
the Wegovy injection generally begins maintenance dosing around week 17, the oral Wegovy tablet reaches its maintenance dose on day 91, and the newer 7.2 mg injectable dose requires an additional step.
Zepbound
starts at 2.5 mg once weekly for four weeks and may then increase in 2.5 mg steps after at least four weeks at each dose; the time required depends on the selected maintenance dose (5, 10, or 15 mg) and tolerability.
Your prescriber can slow this down if needed. That flexibility is one reason FDA-approved products differ from compounded versions, which may have different concentrations, packaging, and dosing instructions, and can increase the risk of measurement or calculation errors.
In reports submitted to the FDA involving compounded semaglutide dosing errors, some patients administered five to 20 times the intended dose.
For the complete week-by-week breakdown, see the full semaglutide dosing guide.
Which is safer, tirzepatide or semaglutide?
Neither drug comes out safer overall in the data we have, and that’s a fair, honest answer rather than a dodge. SURMOUNT-5 measured tolerability, the discontinuation rates covered above, not a safety verdict.
Both drugs carry boxed warnings for thyroid C-cell tumors, several overlapping serious risks (pancreatitis, gallbladder disease, severe allergic reactions), and the same family of GI side effects, just at different rates.
What actually differs comes down to your own history and how your body responds, not a universal ranking. Someone prone to nausea might tolerate one better than the other.
As specific examples: Ozempic has a kidney-risk-reduction indication for adults with type 2 diabetes and chronic kidney disease, while Wegovy has a cardiovascular risk-reduction indication for adults with established cardiovascular disease and obesity or overweight; and someone managing obesity alongside sleep apnea may find Zepbound’s indication more directly relevant.
That’s a judgment call for a physician with your labs and history in front of them, not something a comparison chart can settle.
What semaglutide and tirzepatide cost
Here’s what semaglutide costs, in detail. The short version is that cost depends on a few things: your insurance coverage, which brand and dose you’re prescribed, and whether you qualify for a manufacturer savings program.
Without insurance, injectable semaglutide and tirzepatide products can cost several hundred dollars per month, even up to over $1,000 for 4 weeks of medication.
Actual out-of-pocket costs vary by brand, dose, formulation, pharmacy, insurance coverage, and eligibility for manufacturer savings programs (Wegovy cost and savings; Zepbound pricing).
Semaglutide is available in injectable and oral tablet formulations, while FDA-approved tirzepatide products are currently available as injections.
With insurance that covers GLP-1s for your specific diagnosis, your out-of-pocket cost can drop dramatically, though many plans still exclude weight-loss indications even when they cover that same drug for a diabetes diagnosis.
Brand-name vs compounded: what people actually pay
With coverage and a manufacturer savings card, patients often pay less than $100 for a 4-week supply of Wegovy, Zepbound, or Mounjaro, and in some cases as little as $25.
Without it, manufacturer self-pay programs sit well below retail list price: Wegovy runs $349 a month through NovoCare, Zepbound $299 to $449 through LillyDirect depending on dose, and Wegovy tablets $149 a month at some doses.
Compounded semaglutide and tirzepatide sit in that same band, typically $200 to $400 a month, and some formulations pair the medication with additional ingredients such as glycine, B12, B6, or levocarnitine.
Two things to be clear about. Compounded products are not FDA-approved and are not reviewed by the FDA for safety, effectiveness, or quality. And formulations that add other ingredients have not been studied as a combination.
Dose and formulation are decisions your prescriber makes with your history in front of them.
Cost alone is not a clinical basis for compounding. The FDA’s position is that affordability does not by itself establish the medical need that justifies a compounded product, and manufacturer self-pay programs have narrowed the price gap considerably.
Where a compounded formulation is appropriate, it is because a prescriber has documented a clinical reason an approved product cannot meet, not because it is the cheaper option. A LaSara physician can tell you which applies to you.
What happens to coverage when you reach your goal weight?
This is the part almost nobody plans for. Insurance criteria for GLP-1 coverage generally mirror the FDA-approved indications, which means a BMI of 30 or above, or 27 and above with a weight-related condition.
Losing enough weight to fall below that threshold is the goal of treatment. It can also be what ends your coverage.
For someone who wants to stay on a low maintenance dose to hold their new weight, that shift is abrupt. The $25 copay depends on the plan covering the drug, so when coverage stops the savings card usually goes with it.
There are more options than most people realize:
- Ask your prescriber to submit a continuation-of-therapy request. Many plans have a formulary exception process for exactly this situation.
- Manufacturer self-pay. Wegovy runs $349 a month through NovoCare and Zepbound $299 to $449 through LillyDirect, well below retail list price.
- Consider the oral formulation. Wegovy tablets are $149 a month at some doses, which can make low-dose maintenance considerably cheaper than the injection.
- A compounded product prescribed and monitored by a physician is another route, though compounded products are not FDA-approved and are not reviewed by the FDA for safety, effectiveness, or quality.
Worth raising with your prescriber before you get close to your goal rather than after coverage stops.
Compounded semaglutide and tirzepatide: what to know
Compounded drugs containing semaglutide or tirzepatide are not FDA-approved and are not reviewed by the FDA for safety, effectiveness, or quality before marketing.
The FDA’s concerns with unapproved GLP-1 drugs flags two risks that show up again and again:
Salt-form risk
some compounders use salt forms like semaglutide sodium or semaglutide acetate, chemically different from the active ingredient in FDA-approved products, with no approved use in humans.
Dosing-by-hand risk
some compounded injectable products are supplied in multidose vials, and their concentrations, packaging, and dosing instructions may vary. As of May 2026, the FDA had logged 990 adverse event reports for compounded semaglutide and more than 730 for compounded tirzepatide, many involving reported dosing errors of five to 20 times the intended dose after confusing milligrams, milliliters, and units (FDA dosing-error alert).
Not FDA-approved doesn’t mean unregulated
Compounding pharmacies answer to their state board of pharmacy, follow United States Pharmacopeia preparation standards, and in the case of 503B outsourcing facilities register with the FDA and are inspected under manufacturing practice requirements.
Many also send batches to independent labs for potency and sterility testing. What none of that includes is the premarket review that defines an FDA-approved drug, so the difference is in what’s been formally reviewed, not in whether anyone is watching.
In April 2026 the FDA proposed removing semaglutide and tirzepatide from the 503B bulk substances list, the pathway large outsourcing facilities use.
A final decision is still pending, and it does not affect patient-specific compounding under 503A, the route behind an individual prescription written for you.
LegitScript certification adds an outside check. It verifies a provider’s licensure, legal compliance, medication sourcing, and advertising accuracy. It isn’t a clinical endorsement, and it doesn’t make the product FDA-approved.
LaSara works only with LegitScript-certified compounding pharmacies, and every compounded prescription is written by a physician who has reviewed your full history.
Why a prescriber might choose a compounded formulation
Dose flexibility is the clinical reason compounding exists. A compounded product supplied in a vial can be dosed in small increments using an insulin syringe, which is also where the dosing-error risk covered above comes from.
That same granularity gives a prescriber room to move a patient up or down in steps smaller than a fixed dose allows. For a patient who tolerates one dose poorly but doesn’t respond to the one below it, that can be the difference between staying on treatment and stopping.
This is also the standard the FDA applies. Compounded products are appropriate when a patient’s medical need can’t be met by an available FDA-approved product, and a documented need for a dose or formulation the approved products don’t offer is exactly that kind of case.
It’s a clinical determination made by a prescriber with your history and tolerance in front of them, not a preference you select.
This doesn’t mean every compounding pharmacy operates the same way, and the FDA notes the adverse event reports cited above don’t prove the drug caused the event.
The FDA recommends that compounded drugs be used only when a patient’s medical needs cannot be met by an available FDA-approved drug. Compounded GLP-1s carry a layer of risk FDA-approved products don’t.
How to decide which GLP-1 is right for you
With this much overlap in side effects and safety, the decision usually comes down to specifics a comparison chart can’t see: your health conditions, what you’ve already tried, your insurance formulary, and how you feel about a weekly injection.
Someone managing type 2 diabetes alongside their weight has different considerations than someone focused purely on weight management. And neither medication should be used by someone with a personal or family history of medullary thyroid carcinoma or with MEN 2.
This is exactly the kind of decision that benefits from a real conversation with a physician who can look at your labs, history, and goals together. LaSara’s medical weight loss program pairs you with a physician who can walk through both options and help you land on a plan that fits your life.
FAQs on Semaglutide vs Tirzepatide
Which is better, tirzepatide or semaglutide?
In SURMOUNT-5, the only head-to-head trial between the two, tirzepatide (Zepbound) produced greater average weight loss than semaglutide (Wegovy): 20.2% vs. 13.7% at 72 weeks, with fewer GI-related discontinuations. That still depends on your health history and how each drug affects you personally.
How does tirzepatide work compared with semaglutide?
Semaglutide activates one gut hormone receptor, GLP-1. Tirzepatide activates that receptor plus a second one, GIP. The dual-receptor mechanism may contribute to tirzepatide’s greater average weight reduction in clinical trials, though the precise reasons are not fully established.
Can you switch from semaglutide to tirzepatide?
A prescriber may recommend switching in some circumstances, but the medications are not equivalent dose for dose. Because there is no standard dose-equivalence conversion, the prescriber must select an appropriate starting regimen rather than matching the previous dose number.
Don’t attempt this on your own, and mention any side effects from your current medication first.
Is Ozempic the same as semaglutide?
Ozempic is a brand name. Semaglutide is the active ingredient inside it, the same molecule found in Wegovy. Ozempic is not FDA-approved specifically for weight management; when it is prescribed for that purpose, the use is off-label.
Wegovy is the semaglutide brand with an FDA-approved weight-management indication.
Are semaglutide and tirzepatide used for PCOS?
Neither medication is FDA-approved specifically for PCOS. A clinician may consider off-label use based on a patient’s other diagnoses and individual health profile, but evidence for treating PCOS directly remains limited. That decision belongs to you and your prescriber.
The bottom line
Semaglutide and tirzepatide both work. Both come from the same incretin-based family, and both carry overlapping core risks alongside real, trial-documented results.
The honest difference, in the one trial that’s compared them directly, is degree: In SURMOUNT-5, tirzepatide produced greater average weight loss and fewer GI-related discontinuations than semaglutide at 72 weeks.
The medications have overlapping adverse effects and similar boxed warnings, but their complete safety information is not identical. Which one fits you is a question for a physician, not a blog post.
Ready to talk it through? Book a free consultation with a LaSara physician, and we’ll help you figure out what’s right for your health and goals.
References
- Aronne LJ, Horn DB, le Roux CW, et al. Tirzepatide as compared with semaglutide for the treatment of obesity. New England Journal of Medicine, 2025. DOI: 10.1056/NEJMoa2416394. (SURMOUNT-5)
- U.S. Food and Drug Administration. FDA’s Concerns with Unapproved GLP-1 Drugs Used for Weight Loss.
- U.S. Food and Drug Administration. FDA Alerts Health Care Providers, Compounders and Patients of Dosing Errors Associated with Compounded Semaglutide.
- Novo Nordisk. Wegovy (semaglutide) prescribing information.
- Novo Nordisk. Ozempic (semaglutide) prescribing information.
- Novo Nordisk. Rybelsus (semaglutide) prescribing information.
- Eli Lilly. Zepbound (tirzepatide) prescribing information.
- Eli Lilly. Mounjaro (tirzepatide) prescribing information.
- Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1), body-composition substudy. New England Journal of Medicine, 2021.
- Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1), DXA body-composition substudy. New England Journal of Medicine, 2022.
- Novo Nordisk. Wegovy cost and savings information.
- Eli Lilly. Zepbound coverage and savings.
- Cleveland Clinic. Cleveland Clinic on tirzepatide vs semaglutide.
- Novo Nordisk. Wegovy self-pay and savings pricing, NovoCare Pharmacy.
- Eli Lilly. Zepbound self-pay pricing, LillyDirect.
- LegitScript. Healthcare Certification: what certification verifies.
- U.S. Food and Drug Administration. FDA Proposes to Exclude Semaglutide, Tirzepatide, and Liraglutide on 503B Bulks List, April 30, 2026.
- Federal Register. List of Bulk Drug Substances for Which There Is a Clinical Need Under Section 503B, 91 FR 23431, May 1, 2026.
About the medical reviewer
Courtney Patterson-Manfredi, APRN, is a board-certified Family Nurse Practitioner with more than 15 years of clinical experience and over a decade in telemedicine.
Licensed in 47 states, she specializes in hormone optimization, testosterone replacement therapy (TRT), weight management, sexual health, and longevity-focused care.
Courtney is known for taking the time to understand each patient beyond their labs and medical history, including their lifestyle, priorities, and personal goals, so treatment can be tailored to the way they actually live.
She earned both her Bachelor of Science in Nursing and Master of Science as a Family Nurse Practitioner from Wichita State University and is deeply committed to providing thoughtful, accessible, patient-centered care.