Is tirzepatide better than semaglutide for weight loss?

In the one trial that tested both in the same people, yes. SURMOUNT-5 randomised 751 adults with obesity and without diabetes to the maximum tolerated dose of each drug for 72 weeks and reported a least-squares mean weight change of -20.2% with tirzepatide and -13.7% with semaglutide. Three caveats travel with that: the trial was open-label rather than blinded, it was funded by Eli Lilly, and the semaglutide group received "the maximum tolerated dose of semaglutide (1.7 mg or 2.4 mg)" — meaning some of that arm was below the labelled maintenance dose. It remains the only comparison of the two that is a comparison rather than an arithmetic exercise.

Why not just compare the 15% from STEP 1 with the 21% from SURMOUNT-1?

Because they are two different trials. STEP 1 ran 68 weeks in 1,961 adults with a mean starting weight of 105.3 kg; SURMOUNT-1 ran 72 weeks in 2,539 adults with a mean starting weight of 104.8 kg, four years later, with different sites and a different placebo arm. Placebo alone was −2.4% in one and −3.1% in the other, which is a 0.7-point difference in doing nothing. Subtracting one trial mean from another measures the trials as much as the drugs. When a head-to-head exists, as it does here, it is the only comparison worth quoting.

Does one of them cause less nausea?

Not in a way the labels establish, and the raw figures mislead. The Wegovy label reports nausea in 44% against 16% on placebo; the Zepbound label reports 28% at 15 mg against 8% on placebo. Half the apparent gap is the gap between the two placebo arms, which is a difference between trial populations rather than between drugs. On the one composite both labels report identically — any gastrointestinal adverse reaction — the excess over placebo is 26 points on both, and the proportion who stopped the drug because of it is 4.3% on both. What is genuinely different is that both tirzepatide labels add that the reactions "decreased over time" and no semaglutide label makes that claim.

Is 15 mg of tirzepatide the same as 2.4 mg of semaglutide?

They are both the top of their own weight-management ladder and that is the only sense in which they correspond. No label, guideline or trial states a milligram equivalence between the two molecules, and the ratio between the two ladder tops — a little over six — is an artefact of two companies choosing round numbers, not a potency measurement. If you are switching, the new drug starts at its own labelled starting dose and climbs its own ladder; nothing about your old dose carries across.

How long does it take to reach the full dose on each?

The same 21 weeks, if you climb all the way. Wegovy injection reaches its 2.4 mg maintenance dose at week 17 after four four-week steps, and the 7.2 mg high dose becomes available at week 21 after a further 4 weeks at 2.4 mg. Tirzepatide starts at 2.5 mg and rises in 2.5 mg increments after at least four weeks each, so 15 mg is week 21 at the earliest. The difference is in the middle: semaglutide is at a labelled maintenance dose from week 17, while every rung of the tirzepatide ladder from 5 mg upward is already a maintenance option.

At what a pharmacy pays on invoice, tirzepatide — but the device matters more than the molecule. In the CMS NADAC file dated 2026-09-16, a month of Wegovy 2.4 mg in single-dose pens is $1,415, a month of Zepbound 15 mg in single-dose pens is $1,139, and the same 15 mg dose taken from a four-dose KwikPen is $728. The gap between two devices carrying the identical drug at the identical dose is larger than the gap between the two drugs. None of these is a price you can walk into a pharmacy and pay — NADAC records acquisition cost, not retail, not cash price and not a copay.

Can I take tirzepatide as a tablet?

No. There is no approved oral tirzepatide product of any kind, and anything sold as one is not what it claims to be. Semaglutide is the opposite case — three approved oral products exist: Rybelsus and Ozempic tablets for type 2 diabetes, and Wegovy tablets at 25 mg daily for weight reduction. The oral and injectable semaglutide products are not substitutable on a milligram-to-milligram basis, and the labels say so in those words.

Head to head

Semaglutide vs Tirzepatide

One head-to-head trial answers the weight question. On tolerability, both labels turn out to say the same thing — except for four words only one of them carries.

Reviewed September 2026

The short answer

For weight, there is a head-to-head trial and it favours tirzepatide. SURMOUNT-5 randomised 751 adults with obesity and without diabetes to the maximum tolerated dose of each drug for 72 weeks: 20.2% of body weight lost on tirzepatide against 13.7% on semaglutide. That is one trial, one population, and it is the only comparison on this page that supports a ranking.

Its caveats belong in the same sentence as its result. The trial was open-label, it was funded by the company that makes tirzepatide, and the semaglutide arm was dosed at "1.7 mg or 2.4 mg" — so part of that arm never reached the labelled maintenance dose. It is still far better evidence than the comparison most pages make, which is to hold one drug's trial up against the other's and subtract.

On side effects the labels are closer than the headlines. Nausea reads 44% for semaglutide and 28% for tirzepatide, but the placebo arms were 16% and 8% — and for ANY gastrointestinal reaction, the excess over placebo is 26 points on both labels. Discontinuation for a gut side effect at the top dose is 4.3% on both.

The one tolerability claim that is genuinely asymmetric is four words long. Both tirzepatide labels say the reactions occurred during escalation "and decreased over time". None of the three semaglutide labels says it, or anything like it. "It gets better" is labelled for one of these drugs and is not labelled for the other.

6 of 15 dimensions are materially the same. They are marked below rather than dressed up as differences.

Semaglutide

Ozempic · Wegovy · Rybelsus

A GLP-1 receptor agonist, approved in five separate US dosing schedules across injection and tablets.

Dosing protocol →

Tirzepatide

Mounjaro · Zepbound

A GIP receptor and GLP-1 receptor agonist — a second receptor semaglutide does not touch — injection only.

Dosing protocol →

Side by side

Every row carries how well supported it is. A claim that only reflects common practice is labelled as such rather than presented as fact.

Dimension	Semaglutide	Tirzepatide	Basis
Receptors	GLP-1 receptor agonist	GIP receptor and GLP-1 receptor agonist	labelThe Zepbound label names itself "a glucose-dependent insulinotropic polypeptide (GIP) receptor and glucagon-like peptide-1 (GLP-1) receptor agonist". The second receptor is the whole difference in class.
Head-to-head weight result	13.7% of body weight at week 72	20.2% of body weight at week 72	literatureSURMOUNT-5, 751 adults with obesity and without diabetes, randomised to the maximum tolerated dose of each. Open-label and funded by Eli Lilly; the semaglutide arm was "1.7 mg or 2.4 mg". This is the only figure here that compares the two drugs in one population.
Head-to-head HbA1c result	−1.86 percentage points at 1 mg	−2.01 to −2.30 points across 5, 10 and 15 mg	literatureSURPASS-2, 1,879 patients with type 2 diabetes over 40 weeks, open-label. Tirzepatide was noninferior and superior at all three doses. The semaglutide arm was 1 mg, which is an Ozempic dose and not a weight-management dose.
Label says gut effects decrease over time	No — the sentence stops at escalation	Yes — "and decreased over time"	labelTirzepatide, verbatim: "The majority of nausea, vomiting, and/or diarrhea events occurred during dose escalation and decreased over time." The nearest semaglutide sentence stops four words earlier: "These reactions were most frequently reported during dosage escalation." Neither semaglutide injection label nor the oral label contains the phrase.
Nausea, weight-management pool	44% vs 16% placebo	28% vs 8% placebo	labelTwo separate pooled analyses, so the raw percentages are not a head-to-head. The excess over placebo — 28 points against 20 — is closer than the headline numbers, and the gap between the two placebo arms is half the apparent difference.
Any GI reaction, excess over placebosame	26 points (73% vs 47%)	26 points (56% vs 30%)	labelIdentical to the point, from two different trial pools with very different background rates. It is the single best argument against reading the raw nausea percentages across.
Stopped for a GI reaction, top dosesame	4.3% vs 0.7% placebo	4.3% vs 0.5% placebo	labelThe proportion who actually gave up on the drug because of their gut, at each label's highest weight-management dose. The same figure on both.
Weeks to the top labelled dosesame	Week 17 at 2.4 mg, week 21 at 7.2 mg	Week 21 at 15 mg	labelBoth ladders take 21 weeks to reach the top. Semaglutide gets to its ordinary maintenance dose sooner, at week 17, and only climbs further if 2.4 mg is tolerated for another 4 weeks.
Escalation ladder	0.25 → 0.5 → 1 → 1.7 → 2.4 mg, four weeks each	2.5 mg then 2.5 mg steps: 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg	labelThe milligram figures are not comparable between the two molecules. No label, trial or guideline states a potency ratio, and nothing on this page converts one into the other.
Minimum weeks per stepsame	4 weeks	At least 4 weeks	labelWegovy escalates on the calendar; tirzepatide escalates on tolerance with no upper bound on how long a step may be held.
Oral option	Yes — Rybelsus, Ozempic tablets, Wegovy tablets	None	labelThree approved oral semaglutide products exist, one of them (Wegovy tablets, 25 mg daily) for weight reduction. There is no approved oral tirzepatide of any kind.
Other approved indications	Type 2 diabetes, CV risk reduction, chronic kidney disease, noncirrhotic MASH	Type 2 diabetes, CV risk reduction, moderate-to-severe obstructive sleep apnoea with obesity	labelNeither list is a reason to take the other drug, but they decide coverage. Obstructive sleep apnoea is on the Zepbound label and on no semaglutide label; MASH and chronic kidney disease are on semaglutide labels and on neither tirzepatide label.
Boxed warningsame	Risk of thyroid C-cell tumours	Risk of thyroid C-cell tumours	labelBoth labels open with the same rodent finding and the same contraindication in personal or family history of medullary thyroid carcinoma or MEN 2.
Dosing frequencysame	Once weekly (injection)	Once weekly	label
What a pharmacy paid, per month	$1,415 — Wegovy 2.4 mg single-dose pens	$1,139 single-dose pens, $728 KwikPen — Zepbound 15 mg	literatureCMS NADAC, file dated 2026-09-16. This is invoice cost to a retail pharmacy, not a cash price and not a copay. Note that the device, not the drug, moves the tirzepatide figure by more than the gap between the two molecules.

label: Stated on the FDA label
guideline: Clinical practice guideline
literature: Published literature
practice: Common practice, not documented

Which one

Choose Semaglutide if

You want or need an oral product — semaglutide has three, tirzepatide has none.
Your indication is noncirrhotic MASH, or type 2 diabetes with chronic kidney disease. Neither is on a tirzepatide label.
You are already established on it and tolerating it. A head-to-head average is not a reason to disturb a regimen that is working for you.
It is the one your insurer covers. Coverage decides this for most people and that is a legitimate way to decide it.

Choose Tirzepatide if

Weight reduction is the goal and you have a choice. That is the question SURMOUNT-5 asked, and it answered it in tirzepatide's favour by 6.5 percentage points.
You have moderate-to-severe obstructive sleep apnoea with obesity — a labelled indication for Zepbound and for nothing else in this comparison.
You want the label that actually states the gut effects ease off. Only the tirzepatide labels say so.
You are paying close to acquisition cost and can get the KwikPen rather than single-dose pens — the device gap is larger than the molecule gap.

The two things most likely to decide this are not on either label: what your plan covers, and what is in stock. If you are choosing freely and the goal is weight, the head-to-head favours tirzepatide; if you are already doing well on semaglutide, a trial average is not a reason to switch. What this page will not do is rank them by holding one drug's trial against the other's — the six-point gap you see quoted between STEP 1 and SURMOUNT-1 compares two different populations four years apart, and it is not a measurement of anything.

Frequently asked questions

Is tirzepatide better than semaglutide for weight loss?: In the one trial that tested both in the same people, yes. SURMOUNT-5 randomised 751 adults with obesity and without diabetes to the maximum tolerated dose of each drug for 72 weeks and reported a least-squares mean weight change of -20.2% with tirzepatide and -13.7% with semaglutide. Three caveats travel with that: the trial was open-label rather than blinded, it was funded by Eli Lilly, and the semaglutide group received "the maximum tolerated dose of semaglutide (1.7 mg or 2.4 mg)" — meaning some of that arm was below the labelled maintenance dose. It remains the only comparison of the two that is a comparison rather than an arithmetic exercise.
Why not just compare the 15% from STEP 1 with the 21% from SURMOUNT-1?: Because they are two different trials. STEP 1 ran 68 weeks in 1,961 adults with a mean starting weight of 105.3 kg; SURMOUNT-1 ran 72 weeks in 2,539 adults with a mean starting weight of 104.8 kg, four years later, with different sites and a different placebo arm. Placebo alone was −2.4% in one and −3.1% in the other, which is a 0.7-point difference in doing nothing. Subtracting one trial mean from another measures the trials as much as the drugs. When a head-to-head exists, as it does here, it is the only comparison worth quoting.
Does one of them cause less nausea?: Not in a way the labels establish, and the raw figures mislead. The Wegovy label reports nausea in 44% against 16% on placebo; the Zepbound label reports 28% at 15 mg against 8% on placebo. Half the apparent gap is the gap between the two placebo arms, which is a difference between trial populations rather than between drugs. On the one composite both labels report identically — any gastrointestinal adverse reaction — the excess over placebo is 26 points on both, and the proportion who stopped the drug because of it is 4.3% on both. What is genuinely different is that both tirzepatide labels add that the reactions "decreased over time" and no semaglutide label makes that claim.
Is 15 mg of tirzepatide the same as 2.4 mg of semaglutide?: They are both the top of their own weight-management ladder and that is the only sense in which they correspond. No label, guideline or trial states a milligram equivalence between the two molecules, and the ratio between the two ladder tops — a little over six — is an artefact of two companies choosing round numbers, not a potency measurement. If you are switching, the new drug starts at its own labelled starting dose and climbs its own ladder; nothing about your old dose carries across.
How long does it take to reach the full dose on each?: The same 21 weeks, if you climb all the way. Wegovy injection reaches its 2.4 mg maintenance dose at week 17 after four four-week steps, and the 7.2 mg high dose becomes available at week 21 after a further 4 weeks at 2.4 mg. Tirzepatide starts at 2.5 mg and rises in 2.5 mg increments after at least four weeks each, so 15 mg is week 21 at the earliest. The difference is in the middle: semaglutide is at a labelled maintenance dose from week 17, while every rung of the tirzepatide ladder from 5 mg upward is already a maintenance option.
Which is cheaper?: At what a pharmacy pays on invoice, tirzepatide — but the device matters more than the molecule. In the CMS NADAC file dated 2026-09-16, a month of Wegovy 2.4 mg in single-dose pens is $1,415, a month of Zepbound 15 mg in single-dose pens is $1,139, and the same 15 mg dose taken from a four-dose KwikPen is $728. The gap between two devices carrying the identical drug at the identical dose is larger than the gap between the two drugs. None of these is a price you can walk into a pharmacy and pay — NADAC records acquisition cost, not retail, not cash price and not a copay.
Can I take tirzepatide as a tablet?: No. There is no approved oral tirzepatide product of any kind, and anything sold as one is not what it claims to be. Semaglutide is the opposite case — three approved oral products exist: Rybelsus and Ozempic tablets for type 2 diabetes, and Wegovy tablets at 25 mg daily for weight reduction. The oral and injectable semaglutide products are not substitutable on a milligram-to-milligram basis, and the labels say so in those words.

Sources

Next steps

Compare online weight-loss providersWhich platforms prescribe branded product, which dispense compounded, and what each charges.Medical weight loss, start to finishEligibility, the first six months, monitoring, and what happens if you stop.

Other comparisons

Educational reference, not medical advice. Which medication suits you is a decision for your prescriber.