Comparisons

Semaglutide vs Tirzepatide

Published Jul 4, 2026 · Updated Sep 12, 2026 · 9 minute read

The two molecules behind five brands. They have met in two trials, one in obesity and one in diabetes, and tirzepatide won both on weight. Semaglutide holds the outcomes evidence.

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Key Takeaways

  • Semaglutide activates the GLP-1 receptor. Tirzepatide activates GLP-1 and GIP. Both are weekly injections from rival companies, each sold under two brand names.
  • Weight loss, head-to-head: 20.2% on tirzepatide versus 13.7% on semaglutide 2.4 mg over 72 weeks in SURMOUNT-5.
  • Blood sugar, head-to-head: tirzepatide beat semaglutide 1 mg at every dose in SURPASS-2, with 5.5 kg more weight loss at the top dose.
  • Semaglutide has more outcomes evidence: SELECT, SUSTAIN-6, FLOW, and ESSENCE, all placebo-controlled. Tirzepatide's SURPASS-CVOT showed it matched dulaglutide.
  • Only semaglutide comes as a tablet. Safety warnings are identical. Half-life is about 7 days for semaglutide and 5 for tirzepatide.
Semaglutide Tirzepatide
Receptors GLP-1 GIP and GLP-1
Maker Novo Nordisk Eli Lilly
First approved 2017 2022
Weight-loss brand Wegovy, 2.4 mg or 7.2 mg Zepbound, up to 15 mg
Diabetes brand Ozempic, up to 2 mg Mounjaro, up to 15 mg
Tablet Rybelsus; Wegovy and Ozempic tablets None
Half-life About 1 week About 5 days
Head-to-head trials SURMOUNT-5, SURPASS-2 SURMOUNT-5, SURPASS-2

Weight loss, head-to-head

SURMOUNT-5 randomised 751 adults with obesity and no diabetes to the maximum tolerated dose of either molecule for 72 weeks. It was open-label with no placebo arm.

Head-to-head in obesity: SURMOUNT-5Mean percent weight change at 72 weeks, adults with obesity and no diabetes, n=751, open-label, no placebo
Tirzepatide 10 or 15 mg
Tirzepatide
20.2%
Semaglutide 1.7 or 2.4 mg
Semaglutide
13.7%

Tirzepatide at 10 or 15 mg 20.2% versus semaglutide at 1.7 or 2.4 mg 13.7%. Waist circumference fell 18.4 cm versus 13.0 cm.

Source: Aronne 2025, N Engl J Med

6.5 ppmore weight loss on tirzepatide, and 5.4 cm more off the waist, at 72 weeks.
10% to 25%every weight-loss threshold in that range was reached by more tirzepatide participants.
2.4 mgthe semaglutide ceiling in the trial. The 7.2 mg dose was approved afterwards and has not been compared with tirzepatide.

The 7.2 mg caveat matters. Each molecule’s own placebo-controlled trials show where the top doses now sit.

Each molecule's top dose vs placebo in adults without diabetesMean percent weight change; three trials, not head-to-head
  • Active drug
  • Placebo
Semaglutide 2.4 mgSTEP 1 · 68 weeks
Active drug
14.9%
Placebo
2.4%
Semaglutide 7.2 mgSTEP UP · 72 weeks
Active drug
18.7%
Placebo
3.9%
Tirzepatide 15 mgSURMOUNT-1 · 72 weeks
Active drug
20.9%
Placebo
3.1%

Semaglutide 2.4 mg, STEP 1, 68 weeks: 14.9% vs 2.4%. Semaglutide 7.2 mg, STEP UP, 72 weeks: 18.7% vs 3.9%. Tirzepatide 15 mg, SURMOUNT-1, 72 weeks: 20.9% vs 3.1%.

Source: Wilding 2021; Wharton 2025; Jastreboff 2022

On paper, semaglutide 7.2 mg closes most of the gap, 18.7% against 20.9%. But those are different trials with different populations, and STEP UP found dysaesthesia in 22.9% of the 7.2 mg group versus 6% on 2.4 mg. Until a trial puts tirzepatide against semaglutide 7.2 mg, the direct answer is SURMOUNT-5’s.

Blood sugar, head-to-head

SURPASS-2 randomised 1,879 adults with type 2 diabetes on metformin to tirzepatide 5, 10, or 15 mg or semaglutide 1 mg for 40 weeks. Weight fell 7.6, 9.3, and 11.2 kg on tirzepatide against 5.7 kg on semaglutide. HbA1c followed.

Head-to-head in type 2 diabetes: SURPASS-2HbA1c reduction at 40 weeks in percentage points, n=1,879, open-label
  • Tirzepatide
  • Semaglutide 1 mg
Tirzepatide 5 mg
Tirzepatide
2.01 pp
Tirzepatide 10 mg
Tirzepatide
2.24 pp
Tirzepatide 15 mg
Tirzepatide
2.3 pp
Semaglutide 1 mg
Semaglutide 1 mg
1.86 pp

Tirzepatide 5 mg 2.01, 10 mg 2.24, 15 mg 2.30; semaglutide 1 mg 1.86. Weight fell 7.6, 9.3, and 11.2 kg on tirzepatide against 5.7 kg on semaglutide.

Source: Frías 2021, N Engl J Med

Every tirzepatide dose was non-inferior and then superior. The estimated difference at 15 mg was 0.45 points. Semaglutide 1 mg was the ceiling at the time; Ozempic now goes to 2 mg, which lowered HbA1c by 2.2 points against 1.9 for 1 mg in SUSTAIN FORTE, so the gap at the top of each ladder is smaller than SURPASS-2 alone suggests.

Why two receptors beat one

Semaglutide mimics GLP-1, a gut hormone that slows gastric emptying, boosts insulin when glucose is high, and reduces appetite. Tirzepatide mimics GLP-1 and GIP, the other incretin. On its own, GIP does little for weight. Paired with GLP-1 agonism it appears to add appetite suppression and to blunt nausea at a given level of effect, which would explain why tirzepatide reaches a larger effect at tolerable doses. The mechanism is still being worked out; the GLP-1 vs GLP-2 vs GLP-3 page covers what single, dual, and triple agonists mean, and what is GIP covers the second hormone.

Outcomes: where semaglutide leads

Weight and HbA1c are surrogate endpoints. Heart attacks, strokes, kidney failure, and liver histology are outcomes, and semaglutide has four placebo-controlled heart, kidney, and liver outcomes trials. Tirzepatide has one placebo-controlled cardiovascular trial, SUMMIT, in heart failure with preserved ejection fraction, plus the sleep apnea trials; it has no placebo-controlled trial of heart attack and stroke.

Trial Molecule Population Result
SELECT Semaglutide 2.4 mg Cardiovascular disease and obesity, no diabetes, n=17,604 Major events 6.5% vs 8.0% on placebo, HR 0.80
SUSTAIN-6 Semaglutide 0.5 or 1 mg Type 2 diabetes, n=3,297 Major events 6.6% vs 8.9%, HR 0.74
FLOW Semaglutide 1 mg Type 2 diabetes with kidney disease, n=3,533 Kidney and cardiovascular composite down 24%; all-cause death down 20%
ESSENCE Semaglutide 2.4 mg MASH with fibrosis Combined resolution and fibrosis improvement 32.7% vs 16.1%
SURPASS-CVOT Tirzepatide up to 15 mg Type 2 diabetes with cardiovascular disease, n=13,299 Major events 12.2% vs 13.1% on dulaglutide, HR 0.92, non-inferior
SUMMIT Tirzepatide up to 15 mg Heart failure with preserved ejection fraction and obesity, n=731 Cardiovascular death or worsening heart failure 9.9% vs 15.3% on placebo, HR 0.62; no indication yet
SURMOUNT-OSA Tirzepatide 10 or 15 mg Sleep apnea and obesity AHI down 25 to 29 events per hour vs about 5 on placebo

SURPASS-CVOT tested tirzepatide against dulaglutide, itself a drug shown to reduce cardiovascular events, so it establishes that tirzepatide is at least as good, not how much better than nothing it is. Tirzepatide’s own outcomes trial in obesity, SURMOUNT-MMO, has not reported. Sleep apnea is the one outcome indication tirzepatide holds that semaglutide does not.

Pharmacokinetics and dosing

Semaglutide Tirzepatide
Half-life About 7 days About 5 days
Time to steady state About 4 to 5 weeks About 4 weeks
Present after last dose About 5 weeks About 4 weeks
Dose ladder, diabetes 0.25 to 2 mg 2.5 to 15 mg
Dose ladder, weight 0.25 to 2.4 mg, then 7.2 mg 2.5 to 15 mg
Step interval 4 weeks 4 weeks
Missed-dose window 5 days (Ozempic); take if next dose more than 2 days away (Wegovy) 4 days

Milligrams do not translate between the two. A 1 mg semaglutide dose and a 5 mg tirzepatide dose are different molecules at different potencies, and no label offers a conversion. The half-life visualizer models both.

Safety

The labels are the same on every major point: the boxed warning on thyroid C-cell tumors, the contraindication for medullary thyroid carcinoma history or MEN 2, and the warnings on pancreatitis, gallbladder disease, severe gastrointestinal reactions, and acute kidney injury from dehydration. In SURPASS-2, nausea was 17% to 22% on tirzepatide and 18% on semaglutide, vomiting 6% to 10% and 8%. Semaglutide has five more years of post-marketing data. One difference sits in the drug-interactions section: the tirzepatide label tells people on oral hormonal contraceptives to switch to a non-oral method or add a barrier method for four weeks after starting and after each dose increase; the semaglutide label has no such instruction.

The brand families

Molecule Weight reduction Type 2 diabetes Oral
Semaglutide Wegovy Ozempic Rybelsus; Wegovy tablet; Ozempic tablets
Tirzepatide Zepbound Mounjaro None

Each company sells its molecule under two names so each label carries only the indications its own trials support. Semaglutide’s oral forms are the same peptide with an absorption enhancer; Lilly’s oral GLP-1, orforglipron, is a different molecule.

What comes after two receptors

Retatrutide adds a third receptor, glucagon, and reported 24.2% weight loss at 48 weeks in phase 2. CagriSema pairs semaglutide with an amylin analogue. Both are Lilly’s and Novo’s answers to the same question this page asks. The retatrutide vs tirzepatide page covers the first.

Which comparison you wanted

Whichever molecule, the log entry is the same: product, date, milligrams, site. How GLP-1 tracking works covers what to record.

10. Semaglutide vs Tirzepatide FAQ

  • Which causes more weight loss?

    Tirzepatide, in both direct trials. In SURMOUNT-5, adults with obesity lost 20.2% on tirzepatide versus 13.7% on semaglutide 2.4 mg over 72 weeks. In SURPASS-2, adults with type 2 diabetes lost 11.2 kg on tirzepatide 15 mg versus 5.7 kg on semaglutide 1 mg over 40 weeks. Semaglutide's newer 7.2 mg dose has not been tested against tirzepatide.

  • Why does tirzepatide produce more weight loss?

    The leading explanation is the second receptor. GIP agonism appears to add to GLP-1's effects on appetite and may improve tolerability at a given level of appetite suppression, though the mechanism is still being worked out. Whatever the reason, the effect shows up consistently across trials.

  • Which is safer?

    The labels carry the same boxed warning on thyroid C-cell tumors and the same warnings on pancreatitis, gallbladder disease, and severe gastrointestinal reactions. In SURPASS-2, nausea was 17% to 22% on tirzepatide and 18% on semaglutide. Semaglutide has the longer safety record, approved in 2017 against 2022.

  • Which is better for the heart?

    Semaglutide has the evidence. SELECT cut major cardiovascular events by 20% against placebo in people with cardiovascular disease and obesity, and SUSTAIN-6 by 26% in type 2 diabetes. Tirzepatide's SURPASS-CVOT showed it was non-inferior to dulaglutide, an active drug, in type 2 diabetes. Tirzepatide's only placebo-controlled cardiovascular trial, SUMMIT, was in heart failure with preserved ejection fraction, where it cut cardiovascular death or worsening heart failure by 38%; that is a different outcome from heart attack and stroke prevention and is not yet on any label.

  • Can I switch from one to the other?

    Switching is a prescriber decision. There is no conversion table between the two dose ladders; each label starts at its own first step. Neither label addresses switching from the other molecule.

11. Sources

References used for this article

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