Semaglutide vs Tirzepatide: How the Two Drugs Compare

Semaglutide and tirzepatide are the two best-known medicines in a class of drugs that started in type 2 diabetes care and is now also used for chronic weight management. You may know them by their brand names: semaglutide is sold as Ozempic, Rybelsus and Wegovy, and tirzepatide as Mounjaro and Zepbound. This guide compares semaglutide vs tirzepatide side by side: how each one works, what the FDA has approved it for, what the clinical trials found, and how their safety information differs.

Peptide Labs does not sell semaglutide, tirzepatide or any prescription drug. This article is general information, not medical advice. Both are prescription-only medicines, and the right choice for any one person is a decision to make with a licensed healthcare provider.

Semaglutide vs tirzepatide at a glance

	Semaglutide	Tirzepatide
Manufacturer	Novo Nordisk	Eli Lilly
How it works	GLP-1 receptor agonist	Dual GIP and GLP-1 receptor agonist
Type 2 diabetes brands	Ozempic (weekly injection), Rybelsus (daily tablet)	Mounjaro (weekly injection)
Weight-management brand	Wegovy (weekly injection, plus a daily pill approved in December 2025)	Zepbound (weekly injection)
Other approved uses	Wegovy: lowering the risk of major cardiovascular events in certain adults	Zepbound: moderate to severe obstructive sleep apnea in adults with obesity
Head-to-head result (SURMOUNT-5)	13.7% average weight loss at 72 weeks	20.2% average weight loss at 72 weeks
Boxed warning	Risk of thyroid C-cell tumors	Risk of thyroid C-cell tumors
Prescription required	Yes	Yes

What is the difference between semaglutide and tirzepatide?

The core difference between semaglutide and tirzepatide is how many hormone pathways each one acts on. Both are peptides, short chains of amino acids, designed to mimic gut hormones called incretins that the body releases after eating. (For background, see our guide to what peptides are.)

Semaglutide is a GLP-1 receptor agonist. It mimics glucagon-like peptide-1 (GLP-1), a hormone involved in insulin release, blood sugar control, how quickly the stomach empties, and signals of fullness.

Tirzepatide is a dual agonist. It activates the GLP-1 receptor and also the receptor for glucose-dependent insulinotropic polypeptide (GIP), a second incretin hormone. It was the first approved drug to act on both. Researchers think the added GIP activity is part of why tirzepatide produced larger average effects in trials, though exactly how the two pathways combine is still being studied.

Both drugs are modified so they last in the body for about a week, which is why the injectable brands are taken once weekly. Treatment starts at a low dose that a prescriber raises gradually, mainly to help the digestive system adjust.

FDA-approved brands and uses

Each drug is sold under different brand names for different approved uses. The active ingredient is the same within each family, but the approved doses, devices and indications differ, and a product is only FDA-approved for the uses on its own label.

Semaglutide brands

• Ozempic: once-weekly injection for adults with type 2 diabetes, alongside diet and exercise. Its label also covers lowering the risk of major cardiovascular events in adults with type 2 diabetes and heart disease, and of kidney disease worsening in adults with type 2 diabetes and chronic kidney disease.
• Rybelsus: a once-daily tablet for adults with type 2 diabetes.
• Wegovy: once-weekly injection for chronic weight management in adults and children aged 12 and older with obesity, and in adults with overweight plus a weight-related condition. It is also approved to lower the risk of heart attack, stroke and cardiovascular death in adults with heart disease and obesity or overweight. In December 2025 the FDA also approved a once-daily Wegovy pill for chronic weight management.

Tirzepatide brands

• Mounjaro: once-weekly injection for adults with type 2 diabetes, alongside diet and exercise (approved in 2022).
• Zepbound: once-weekly injection for chronic weight management in adults with obesity, or with overweight plus a weight-related condition (approved in 2023). In December 2024 it was also approved for moderate to severe obstructive sleep apnea in adults with obesity. It comes in single-dose pens and single-dose vials.

For a plain explanation of what these approvals mean, read what “FDA-approved prescription drug” means for semaglutide and tirzepatide.

Zepbound vs Wegovy: weight-management results

Zepbound vs Wegovy is the comparison most people mean when they ask whether tirzepatide or semaglutide works better for weight loss. For years the only answer came from separate trials run against placebo, and comparing across trials is unreliable because the people enrolled, the length of treatment and the methods differ.

• STEP 1 (semaglutide 2.4 mg, the Wegovy dose): adults with obesity or overweight without diabetes lost about 15% of body weight on average over 68 weeks, compared with about 2% on placebo.
• SURMOUNT-1 (tirzepatide, the Zepbound doses): adults with obesity or overweight without diabetes lost an average of about 15% to 21% of body weight over 72 weeks depending on dose, compared with about 3% on placebo.

The direct comparison came from SURMOUNT-5, a head-to-head trial published in the New England Journal of Medicine in 2025. About 750 adults with obesity and without type 2 diabetes took either tirzepatide or semaglutide at the highest dose they could tolerate for 72 weeks. Average weight loss was 20.2% with tirzepatide and 13.7% with semaglutide, and average waist circumference fell by about 18 cm and 13 cm respectively. The trial was open-label and funded by Eli Lilly, which makes tirzepatide.

These figures are group averages. In every trial, individual results varied widely, some people stopped treatment because of side effects, and studies of both drugs found that much of the weight tends to return after treatment stops.

Mounjaro vs Ozempic for type 2 diabetes

For type 2 diabetes, the main head-to-head evidence comes from SURPASS-2, a 40-week trial published in 2021 that compared three doses of tirzepatide with semaglutide 1 mg (an Ozempic dose at the time) in adults already taking metformin. All three tirzepatide doses lowered A1C, the standard measure of long-term blood sugar, more than semaglutide did, and produced more weight loss. Rates of digestive side effects were broadly similar between the groups.

Mounjaro vs Ozempic is not only about A1C, though. Ozempic has label indications for cardiovascular and kidney risk reduction in certain adults with type 2 diabetes, based on dedicated outcome trials, and prescribers weigh factors such as a patient’s heart and kidney health, other medicines, insurance coverage and supply.

Semaglutide vs tirzepatide side effects and safety

The safety profiles of semaglutide and tirzepatide overlap heavily because both act on the GLP-1 pathway. Details differ by product, so the official prescribing information and Medication Guide for each brand are the authoritative sources.

Common side effects

For both drugs, the most commonly reported side effects are digestive: nausea, diarrhea, vomiting, constipation, stomach pain and indigestion. They are most frequent while the dose is being increased and often ease over time. In SURMOUNT-5, digestive side effects were the most common in both groups and occurred at similar rates.

Shared warnings

• Both carry a boxed warning about thyroid C-cell tumors, which were seen in rodent studies; it is not known whether this applies to humans. Neither should be used by people with a personal or family history of medullary thyroid carcinoma or with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
• Labels for both warn about pancreatitis, gallbladder problems, low blood sugar when combined with insulin or a sulfonylurea, kidney problems linked to dehydration from vomiting or diarrhea, and serious allergic reactions.
• The weight-management products advise monitoring for depression and suicidal thoughts.
• Because these drugs slow stomach emptying, patients are asked to tell their care team before surgery or procedures that involve anesthesia or sedation.

A difference worth knowing: oral contraceptives

Tirzepatide can make oral hormonal birth control less effective. Its labels advise people using oral contraceptives to switch to a non-oral method, or add a barrier method, for 4 weeks after starting tirzepatide and for 4 weeks after each dose increase. Semaglutide’s labels do not carry the same advice. Neither drug should be used during pregnancy.

Switching from semaglutide to tirzepatide

People sometimes switch from semaglutide to tirzepatide, or the other way round, because of side effects, results, insurance coverage or supply. There is no official dose-conversion chart between the two drugs, and they are not taken together. A prescriber decides the starting dose and timing of a switch, usually taking into account the current dose, how it has been tolerated and when the last dose was taken. Switching without that guidance risks either stronger side effects or a gap in treatment.

Compounded semaglutide and tirzepatide

During the drug shortages of 2022 to 2024, pharmacies were allowed to compound copies of semaglutide and tirzepatide. The FDA declared the tirzepatide shortage resolved in late 2024 and the semaglutide shortage resolved in February 2025. Once a shortage ends, compounding pharmacies can no longer make essentially identical copies routinely, and the FDA’s grace periods for that ended in 2025.

Compounded drugs are not FDA-approved, which means the FDA has not reviewed them for safety, effectiveness or quality before they reach patients. The FDA has reported adverse events linked to compounded versions, including dosing errors, and has warned that some products use salt forms such as semaglutide sodium, which are not the ingredient in the approved drugs. Products sold online as “research use only” or “not for human consumption” are not approved for use in people at all, and the FDA has also warned about counterfeit pens.

GLP-1 supplements are not semaglutide or tirzepatide

Many over-the-counter supplements now use “GLP-1” in their names. They are dietary supplements, usually built on fiber, berberine or probiotics, and they are not GLP-1 medications. They do not contain semaglutide or tirzepatide, and none is FDA-approved to treat diabetes or obesity. Our guide to what “GLP-1 support” labels mean explains the difference.

What comes next: newer drugs in development

Several newer compounds build on the same approach, and none of them is FDA-approved as of this writing. Retatrutide acts on three receptors (GIP, GLP-1 and glucagon), and CagriSema combines semaglutide with the amylin analog cagrilintide. Both are investigational and available only in clinical trials. Our Peptide Guide lists the U.S. regulatory status of these and other peptides, including individual profiles of semaglutide and tirzepatide.

Frequently Asked Questions

Is tirzepatide better than semaglutide?

In the head-to-head SURMOUNT-5 trial, adults without diabetes lost more weight on average with tirzepatide (20.2%) than with semaglutide (13.7%) over 72 weeks, and in SURPASS-2 tirzepatide lowered A1C more in type 2 diabetes. Better on average does not mean better for everyone: tolerability, other health conditions, approved uses, coverage and supply all matter, and a prescriber weighs them.

Are Mounjaro and Zepbound the same drug?

Yes. Both contain tirzepatide. Mounjaro is approved for type 2 diabetes and Zepbound for chronic weight management and obstructive sleep apnea in adults with obesity.

Are Ozempic and Wegovy the same drug?

Both contain semaglutide, but they are approved for different uses and at different doses: Ozempic for type 2 diabetes and Wegovy for chronic weight management and cardiovascular risk reduction in certain adults.

Is there a pill version of semaglutide or tirzepatide?

Semaglutide is available as a daily tablet, Rybelsus, for type 2 diabetes, and the FDA approved a daily Wegovy pill for weight management in December 2025. Tirzepatide is available only as a weekly injection.

Do semaglutide and tirzepatide have the same side effects?

Largely, yes. Both most commonly cause digestive side effects such as nausea, diarrhea, vomiting and constipation, and both carry a boxed warning about thyroid C-cell tumors. One difference is that tirzepatide can reduce the effectiveness of oral contraceptives.

Can I buy semaglutide or tirzepatide without a prescription?

No. In the United States both are prescription-only drugs. Products sold without a prescription, including "research use only" peptides, are not FDA-approved for human use.

Last reviewed September 2026. Drug approvals and labels change; check the current prescribing information or ask a pharmacist for the latest details. These statements are general information and are not a substitute for advice from a licensed healthcare provider.