What's the Difference Between Semaglutide and Tirzepatide? A Complete Side-by-Side Comparison

Key Takeaways

• Semaglutide is a GLP-1 receptor agonist. Tirzepatide is a dual GLP-1 and GIP receptor agonist. The dual mechanism is the main reason tirzepatide produces larger weight loss and A1C reductions in head-to-head trials.
• Both drugs are weekly subcutaneous injections approved for type 2 diabetes (semaglutide as Ozempic, tirzepatide as Mounjaro). Both have weight-loss-approved siblings (Wegovy and Zepbound respectively).
• In SURPASS-2 (head-to-head, type 2 diabetes), tirzepatide produced A1C reductions of 2.0 to 2.3 points vs 1.86 points for semaglutide 1 mg, and weight loss of 7.6 kg to 11.2 kg vs 5.7 kg.
• In SURMOUNT-5 (head-to-head, obesity without diabetes), tirzepatide produced 20.2% mean weight loss vs 13.7% for semaglutide 2.4 mg over 72 weeks.
• Side effect profiles overlap. Both cause nausea, diarrhea, vomiting, and constipation. Tirzepatide has marginally higher GI rates at peak doses, but discontinuation rates are similar between the two drugs.

Direct answer (40-60 words)

Semaglutide is a GLP-1 receptor agonist; tirzepatide is a dual GLP-1 and GIP receptor agonist. Both are weekly injections for type 2 diabetes and obesity. In head-to-head trials, tirzepatide produces larger weight loss (about 20% vs 14%) and bigger A1C reductions. Side effects overlap. Tirzepatide is the newer drug, approved in 2022.

Table of contents

1. The 30-second answer
2. Mechanism of action: GLP-1 only vs GLP-1 plus GIP
3. Brand names: which drug is in which product
4. Head-to-head clinical trial data
5. Dosing schedules and titration
6. Side effects compared
7. Cardiovascular and other outcomes data
8. Cost and insurance coverage
9. Pen design, storage, and travel
10. How to decide between them with your provider
11. Compounded versions of each drug
12. FAQ

Mechanism of action: GLP-1 only vs GLP-1 plus GIP

This is the single most important difference between the two drugs.

Semaglutide acts on GLP-1 receptors only. GLP-1 (glucagon-like peptide-1) is a gut hormone released in response to meals. Semaglutide is a 31-amino-acid peptide based on the natural GLP-1 sequence with a fatty-acid side chain (C18 diacid) that extends its half-life to about 7 days. When semaglutide binds the GLP-1 receptor, it:

• Stimulates glucose-dependent insulin secretion from pancreatic beta cells
• Suppresses glucagon release from alpha cells
• Slows gastric emptying
• Reduces appetite via central nervous system effects (hypothalamus, brainstem)
• Improves cardiovascular outcomes in established CV disease (per SUSTAIN-6 and SELECT)

Tirzepatide acts on both GLP-1 and GIP receptors. GIP (glucose-dependent insulinotropic polypeptide) is a separate gut hormone with overlapping but distinct effects on insulin secretion and adipose tissue. Tirzepatide is a 39-amino-acid peptide engineered with a GIP-based scaffold modified to also bind the GLP-1 receptor. The dual-receptor activation produces:

• Stronger insulin secretion (additive GLP-1 and GIP effects)
• Larger gastric emptying delay than GLP-1 alone
• Possibly enhanced lipid metabolism and energy expenditure via GIP-mediated effects
• Greater weight loss in head-to-head trials

The GIP component is what differentiates tirzepatide from earlier GLP-1 agonists. Whether GIP activation alone produces meaningful metabolic effects has been debated for years; in combination with GLP-1, the data is now clear that the dual approach outperforms GLP-1 alone for weight loss.

A 2024 Nature Metabolism paper (Müller et al.) reviewed the combined GIP/GLP-1 receptor pharmacology and concluded that GIP receptor activation enhances the satiety and metabolic effects of GLP-1 activation rather than acting independently.

Brand names: which drug is in which product

Both drugs are sold under multiple brand names depending on the FDA-approved indication.

Semaglutide products:

• Ozempic (Novo Nordisk): subcutaneous injection 0.25 mg, 0.5 mg, 1 mg, 2 mg weekly. FDA-approved for type 2 diabetes (2017) and reduced cardiovascular risk in T2D + established CVD (2020).
• Wegovy (Novo Nordisk): subcutaneous injection 0.25 mg titrated up to 2.4 mg weekly. FDA-approved for chronic weight management (2021) and reduced major adverse cardiovascular events in adults with overweight/obesity and CVD (2024).
• Rybelsus (Novo Nordisk): oral tablet 3 mg, 7 mg, 14 mg daily. FDA-approved for type 2 diabetes (2019).

Tirzepatide products:

• Mounjaro (Eli Lilly): subcutaneous injection 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg weekly. FDA-approved for type 2 diabetes (2022).
• Zepbound (Eli Lilly): subcutaneous injection same dose range. FDA-approved for chronic weight management (2023) and obstructive sleep apnea in adults with obesity (2024).

So when someone says "I'm on semaglutide for weight loss," they're typically on Wegovy. "Tirzepatide for weight loss" is Zepbound. Compounded versions of both active ingredients are also available through state-licensed compounding pharmacies under specific FDA shortage rules.

Head-to-head clinical trial data

Two large head-to-head trials directly compared the two drugs.

SURPASS-2 (Frias et al., NEJM 2021): N = 1,879 adults with type 2 diabetes, 40-week comparison.

Measure	Tirzepatide 5 mg	Tirzepatide 10 mg	Tirzepatide 15 mg	Semaglutide 1 mg
A1C reduction	-2.01%	-2.24%	-2.30%	-1.86%
Body weight change	-7.6 kg	-9.3 kg	-11.2 kg	-5.7 kg
Patients reaching A1C < 7%	85%	89%	86%	79%
Patients reaching A1C < 5.7% (non-diabetic range)	27%	40%	46%	19%

SURMOUNT-5 (Aronne et al., NEJM 2025): N = 751 adults with obesity but without diabetes, 72-week comparison.

Measure	Tirzepatide max-tolerated dose	Semaglutide 2.4 mg
Mean weight loss	-20.2%	-13.7%
Patients losing ≥ 25% body weight	32%	16%
Patients losing ≥ 15% body weight	64%	40%
Treatment discontinuation due to AEs	6.1%	8.0%

The pattern is consistent across both populations. Tirzepatide produces larger metabolic effects than semaglutide at maximum doses. The magnitude of difference is approximately 5 to 7 percentage points of body weight loss for obesity, and 0.15 to 0.45 percentage points of A1C for diabetes.

For patients comparing the two drugs in lower-dose ranges, the gap narrows. Semaglutide 1 mg and tirzepatide 5 mg produce closer effects than semaglutide 2.4 mg and tirzepatide 15 mg.

Dosing schedules and titration

Both drugs require gradual dose escalation to reduce GI side effects. The titration schedules differ.

Semaglutide (Ozempic for diabetes):

• Weeks 1 to 4: 0.25 mg weekly
• Weeks 5 to 8: 0.5 mg weekly
• Optional: 1 mg weekly after at least 4 weeks at 0.5 mg
• Maximum: 2 mg weekly

Semaglutide (Wegovy for weight loss):

• Weeks 1 to 4: 0.25 mg
• Weeks 5 to 8: 0.5 mg
• Weeks 9 to 12: 1 mg
• Weeks 13 to 16: 1.7 mg
• Weeks 17+: 2.4 mg (target maintenance)

Tirzepatide (Mounjaro and Zepbound):

• Weeks 1 to 4: 2.5 mg weekly
• Weeks 5 to 8: 5 mg weekly
• Optional: 7.5 mg, 10 mg, 12.5 mg, 15 mg (escalate every 4 weeks if tolerated)
• Maximum: 15 mg weekly

The two drugs are not dose-equivalent. There is no "1 mg semaglutide equals X mg tirzepatide" conversion. Each drug has its own dose range based on the receptor binding affinity and pharmacokinetics of the molecule.

If switching between drugs, providers typically restart titration at the new drug's lowest starting dose with re-escalation every 4 weeks.

Side effects compared

Side effect profiles are similar but not identical.

Side effect	Tirzepatide 15 mg	Semaglutide 2.4 mg
Nausea	22 to 31%	16 to 44% (varies by trial)
Diarrhea	17 to 23%	12 to 30%
Vomiting	9 to 12%	5 to 24%
Constipation	7 to 11%	5 to 24%
Reflux / heartburn	8 to 10%	5 to 11%
Treatment discontinuation due to AEs	6 to 7%	5 to 8%

(Sources: SURMOUNT-1, SURPASS-2, STEP 1, STEP 4 trial reports.)

The wider semaglutide range reflects that the STEP trials (Wegovy 2.4 mg) reported higher GI rates than SUSTAIN trials (Ozempic 1 mg). At maximum doses, both drugs cause meaningful GI symptoms in the majority of patients during titration.

Both share boxed warnings:

• Risk of thyroid C-cell tumors (rodent studies; clinical relevance unknown)
• Contraindicated in patients with personal/family history of medullary thyroid carcinoma or MEN-2

Both share other warnings:

• Pancreatitis (rare, but reported)
• Gallbladder disease (gallstones during rapid weight loss)
• Acute kidney injury (typically secondary to dehydration from vomiting/diarrhea)
• Hypoglycemia when combined with insulin or sulfonylureas
• Hypersensitivity reactions

A 2024 meta-analysis (Karagiannis et al., Diabetologia 2024) of GLP-1 vs dual GIP/GLP-1 head-to-head trials found that tirzepatide had marginally higher rates of nausea and vomiting at maximum doses, but treatment discontinuation rates were comparable.

Cardiovascular and other outcomes data

The cardiovascular evidence base is currently larger for semaglutide than tirzepatide.

Semaglutide cardiovascular outcomes:

• SUSTAIN-6 (Marso et al., NEJM 2016): semaglutide reduced major adverse cardiovascular events by 26% in patients with type 2 diabetes and high CV risk.
• SELECT (Lincoff et al., NEJM 2023): semaglutide 2.4 mg reduced cardiovascular events by 20% in adults with overweight/obesity and established CV disease but without diabetes.

Tirzepatide cardiovascular outcomes:

• SURPASS-CVOT (results published 2024): tirzepatide non-inferior to dulaglutide for MACE in patients with type 2 diabetes and CV risk. Tirzepatide showed numerical superiority but the trial was powered for non-inferiority. A separate obesity CVOT (SURMOUNT-MMO) is enrolling.

Other endpoints:

• Heart failure with preserved ejection fraction (HFpEF): STEP-HFpEF (semaglutide) and SUMMIT (tirzepatide) both showed improvements in HFpEF symptoms with weight loss and reduced inflammation.
• Obstructive sleep apnea: SURMOUNT-OSA (tirzepatide) led to FDA approval of Zepbound for OSA in 2024.
• NASH/MASH: semaglutide ESSENCE trial showed liver fibrosis improvement.
• Kidney outcomes: FLOW (semaglutide) showed slowed CKD progression in T2D patients with CKD.

For patients with established CV disease, semaglutide currently has the larger evidence base. For patients with HFpEF, OSA, or maximum weight loss as the priority, tirzepatide has stronger trial-level evidence.

Cost and insurance coverage

Product	List price (Q1 2026, monthly)	Manufacturer savings card minimum
Ozempic (semaglutide)	$997 to $1,029	As low as $25 (commercial + T2D)
Wegovy (semaglutide)	$1,349	$0 to $225 with eligible coverage
Mounjaro (tirzepatide)	$1,069	As low as $25 (commercial + T2D)
Zepbound (tirzepatide)	$1,059 to $1,086	$25 to $650 depending on coverage
Rybelsus (oral semaglutide)	$987	$10 to $25

Commercial insurance covers most of these products with prior authorization for type 2 diabetes. Weight-loss-only coverage is plan-specific.

Medicare Part D covers Ozempic and Mounjaro for type 2 diabetes. Statutory rules generally exclude Medicare coverage of weight-loss medications, so off-label or labeled weight-loss prescriptions (Wegovy, Zepbound) are typically not covered. The Inflation Reduction Act may change this for some plans starting 2026.

A 2024 KFF analysis estimated average net cost (after manufacturer rebates and savings cards) at $87 monthly for commercially insured T2D patients, similar across both Ozempic and Mounjaro.

Compounded semaglutide and tirzepatide are typically priced at $200 to $400 monthly through telehealth platforms, depending on dose and pharmacy. (See section 11.)

Pen design, storage, and travel

Feature	Semaglutide pens	Tirzepatide pens
Manufacturer	Novo Nordisk	Eli Lilly
Doses per pen	Multi-dose (4 to 6 doses)	Single-dose (1 dose)
Dose adjustment	Dial dose on pen	Pen replaced for each dose
Refrigeration before first use	36 to 46 °F	36 to 46 °F
Room temperature stability after first use	56 days	21 days unrefrigerated
Typical needle	32G pen needle (patient-attached)	32G pen needle (patient-attached)

The tirzepatide single-dose pen is mechanically simpler (no dialing) but produces more medical waste than a multi-dose pen. The semaglutide multi-dose pen requires patients to track which dose they're on each week.

Both products are subcutaneous injections in the abdomen, thigh, or upper arm. Site rotation is recommended to prevent injection-site reactions.

For travel, both can be transported in an insulated bag with a frozen gel pack (not direct ice contact, which can freeze and degrade the peptide). TSA permits both medications in carry-on luggage with appropriate documentation.

How to decide between them with your provider

The choice between semaglutide and tirzepatide comes down to seven factors most often:

1. Indication and FDA approval. For diabetes, both Ozempic and Mounjaro are approved. For weight loss specifically, the FDA-approved options are Wegovy (semaglutide) and Zepbound (tirzepatide), not Ozempic or Mounjaro. For OSA in obese adults, only Zepbound is FDA-approved.
2. Insurance coverage. Your plan's formulary may prefer one over the other; prior authorization criteria can differ.
3. Weight-loss goals. If maximum weight loss is the priority, tirzepatide produces somewhat greater results in head-to-head data.
4. Cardiovascular history. If you have established CV disease, semaglutide has a larger CV outcomes evidence base.
5. Tolerance to GI side effects. Tirzepatide patients had marginally higher GI rates at peak doses; if you've tried one and tolerated it poorly, switching may or may not help.
6. Comorbid conditions. OSA, HFpEF, NASH/MASH, CKD all have specific outcomes data favoring one drug or the other.
7. Pen preference. Multi-dose semaglutide pens vs single-dose tirzepatide pens; some patients have strong preferences.

Self-selection between brand-name GLP-1 medications is not appropriate. The decision should involve your provider's review of medical history, contraindications, and treatment goals. (See our guide to getting started on GLP-1 therapy for the typical evaluation process.)

Compounded versions of each drug

Compounded semaglutide and compounded tirzepatide are not the same as the FDA-approved brand-name products. They contain the same active ingredients but are prepared by state-licensed compounding pharmacies in response to individual prescriptions, not manufactured under FDA New Drug Application standards.

Compounded versions are legally available under specific FDA shortage rules (section 503A of the Federal Food, Drug, and Cosmetic Act). When a brand-name drug is on the FDA shortage list, compounding pharmacies can prepare a copy. The FDA removed semaglutide and tirzepatide from its shortage list in early 2025, then partially reinstated specific dosage forms later in the year.

Compounded prices typically run $200 to $400 monthly through legitimate telehealth platforms, depending on dose, vial size, and pharmacy. The prescription requires the same provider evaluation as brand-name products. The compounded vial is supplied with the pharmacy's reconstitution and dose-draw instructions; the patient draws weekly doses on a U-100 insulin syringe.

Compounded versions sometimes contain additives like vitamin B12 (cyanocobalamin), which produces a pink, red, or orange tint. Plain compounded semaglutide and tirzepatide are clear and colorless. (See our why is my compounded semaglutide red and bacteriostatic water for 10 mg semaglutide guides for more.)

FAQ

What's the difference between semaglutide and tirzepatide? Semaglutide is a GLP-1 receptor agonist. Tirzepatide is a dual GLP-1 and GIP receptor agonist. The dual mechanism produces larger weight loss and bigger A1C reductions in head-to-head trials. Both are weekly subcutaneous injections.

Which is more effective, semaglutide or tirzepatide? For weight loss and A1C reduction at maximum doses, tirzepatide has produced larger effects in head-to-head trials. SURMOUNT-5 (2025) showed 20.2% mean weight loss with tirzepatide vs 13.7% with semaglutide 2.4 mg. Individual response varies.

Are the side effects of semaglutide and tirzepatide the same? Mostly yes. Both cause nausea, diarrhea, vomiting, constipation, and reduced appetite. Tirzepatide has marginally higher GI rates at peak doses, but treatment discontinuation rates are similar between the two drugs.

Can I switch from semaglutide to tirzepatide? Yes, with provider supervision. There is no direct dose conversion. Most clinicians restart titration from tirzepatide's 2.5 mg starting dose with re-escalation every 4 weeks if tolerated. Switching is typically done because of insurance changes, side effect issues, or efficacy goals.

Are Ozempic and Wegovy the same drug? Both contain semaglutide. Ozempic is FDA-approved for type 2 diabetes; Wegovy is FDA-approved for chronic weight management. They have different dose schedules (Ozempic max 2 mg, Wegovy max 2.4 mg). Insurance coverage differs.

Are Mounjaro and Zepbound the same drug? Both contain tirzepatide. Mounjaro is FDA-approved for type 2 diabetes; Zepbound is FDA-approved for chronic weight management and (since 2024) obstructive sleep apnea. The dose ranges are the same. Insurance coverage differs.

Why is tirzepatide considered more effective for weight loss? The dual GLP-1 and GIP receptor activation produces stronger appetite suppression and possibly enhanced metabolic effects compared to GLP-1 alone. The mechanism difference shows up consistently in head-to-head trials.

Can I take semaglutide and tirzepatide together? No. Combining two GLP-1 receptor agonists (or a GLP-1 with a dual GLP-1/GIP) is not approved and risks additive adverse effects without proportional benefit. Patients should be on one or the other.

Which has better cardiovascular outcomes data? Semaglutide currently has the larger CV evidence base, with SUSTAIN-6 (T2D) and SELECT (obesity without diabetes) both showing meaningful CV risk reduction. Tirzepatide's SURPASS-CVOT showed non-inferiority with numerical advantage; the obesity CVOT is enrolling.

Is compounded semaglutide the same as Ozempic? No. Both contain semaglutide, but Ozempic is FDA-approved and manufactured by Novo Nordisk under New Drug Application standards. Compounded semaglutide is prepared by a state-licensed compounding pharmacy and is not FDA-approved. The two products are not interchangeable.

Which is cheaper, semaglutide or tirzepatide? List prices are similar across brand-name products, with Ozempic slightly lower than Mounjaro. Manufacturer savings cards bring eligible commercially insured patients to as low as $25 monthly on either drug. Compounded versions of both run $200 to $400 monthly.

How long do you have to stay on semaglutide or tirzepatide? GLP-1 therapy is generally considered chronic for both diabetes and weight management. Stopping either drug typically results in weight regain over 12 to 24 months and loss of A1C control in diabetic patients. The decision to stop should be a provider-guided clinical conversation.

Do they have the same boxed warning? Yes. Both semaglutide and tirzepatide carry the same boxed warning about thyroid C-cell tumors based on rodent studies, and both are contraindicated in patients with a personal or family history of medullary thyroid carcinoma or MEN-2.

Sources (numbered list)

1. Frias JP, et al. Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes (SURPASS-2). N Engl J Med. 2021;385:503-515.
2. Aronne LJ, et al. Tirzepatide vs semaglutide for obesity (SURMOUNT-5). N Engl J Med. 2025.
3. Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med. 2022;387:205-216.
4. Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021;384:989-1002.
5. Marso SP, et al. Semaglutide and cardiovascular outcomes in type 2 diabetes (SUSTAIN-6). N Engl J Med. 2016;375:1834-1844.
6. Lincoff AM, et al. Semaglutide and cardiovascular outcomes in obesity without diabetes (SELECT). N Engl J Med. 2023;389:2221-2232.
7. Müller TD, et al. GIP and GLP-1 dual agonism: pharmacology and clinical translation. Nature Metabolism. 2024.
8. Karagiannis T, et al. Comparative efficacy of GLP-1 and dual GIP/GLP-1 receptor agonists. Diabetologia. 2024.
9. Eli Lilly. Mounjaro and Zepbound Prescribing Information, 2026 update.
10. Novo Nordisk. Ozempic, Wegovy, and Rybelsus Prescribing Information, 2026 update.
11. Malhotra A, et al. Tirzepatide for the treatment of obstructive sleep apnea (SURMOUNT-OSA). N Engl J Med. 2024.
12. Newsome PN, et al. Semaglutide for nonalcoholic steatohepatitis (ESSENCE). N Engl J Med. 2024.
13. American Diabetes Association. Standards of Care in Diabetes 2026, Pharmacologic approaches to glycemic treatment.

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Compounded Medication Notice. Compounded semaglutide and tirzepatide are not FDA-approved. They are prepared by a state-licensed compounding pharmacy in response to an individual prescription. Compounded medications have not undergone the same review process as FDA-approved drugs and are not interchangeable with brand-name products.

Results Disclaimer. Individual results vary. Weight-loss outcomes depend on diet, exercise, adherence, baseline weight, and individual response to treatment. Statements about average outcomes reference published clinical trial data, which may differ from real-world results.

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