Evidence-based comparison

Semaglutide vs Tirzepatide: Data and Cost

A cited, side-by-side look at how semaglutide and tirzepatide compare on trial results, side effects, dosing, and cost.

Last updated: 2026-08-17

1.Quick Answer

Semaglutide and tirzepatide are both once-weekly injectable GLP-1-based medications for weight management. Tirzepatide is a dual GLP-1/GIP agonist, which is thought to drive its larger average weight loss in trials. In the only randomized head-to-head trial (SURMOUNT-5), tirzepatide produced greater average weight loss than semaglutide - 20.2% vs. 13.7% at 72 weeks^[5] - with a lower rate of GI-related discontinuation. Both carry similar gastrointestinal side effects and the same FDA boxed warning for thyroid C-cell tumors. Neither is universally “better”: the right medication, if any, is a decision a licensed provider makes with each patient individually.

2.How Each Drug Works

Both drugs are incretin-mimetic therapies that reduce appetite and slow gastric emptying rather than directly increasing metabolism or “burning” fat^[1].

Semaglutide is a GLP-1 (glucagon-like peptide-1) receptor agonist. It activates GLP-1 receptors in appetite-regulating brain regions (central pathway) and slows gastric emptying while enhancing glucose-dependent insulin secretion (peripheral pathway)^[1].
Tirzepatide is a dual agonist that activates both the GLP-1 receptor and the GIP (glucose-dependent insulinotropic polypeptide) receptor - a second incretin pathway semaglutide does not target. This dual mechanism may contribute to tirzepatide's larger average weight-loss effect in trials^[4].

3.Head-to-Head Trial: SURMOUNT-5

SURMOUNT-5 (Aronne et al., NEJM 2025) is the only randomized trial to compare the two drugs directly in the same population under the same protocol^[5].

751 adults with obesity (or overweight plus a weight-related condition), no type 2 diabetes.
At 72 weeks: tirzepatide −20.2% body weight vs. semaglutide −13.7% (P<0.001).
Tirzepatide also had a lower rate of GI-related treatment discontinuation than semaglutide in this trial.

4.Individual Pivotal Trials

Outside the head-to-head trial, each drug also has its own placebo-controlled pivotal trial. These enrolled different populations under different protocols, so treat the numbers below as context, not a direct comparison.

Semaglutide 2.4 mg, STEP 1 (Wilding et al., NEJM 2021): Mean weight loss of 14.9% at 68 weeks vs. 2.4% with placebo; 86.4% of the semaglutide group achieved ≥5% loss vs. 31.5% placebo^[2].
Semaglutide, STEP 5 (2-year data): −15.2% vs. −2.6% placebo at week 104, showing the effect holds while treatment continues^[3].
Tirzepatide, SURMOUNT-1 (Jastreboff et al., NEJM 2022): Mean weight loss of 16.0% (5 mg), 21.4% (10 mg), and 22.5% (15 mg) vs. 2.4% placebo at 72 weeks; 89-96% achieved ≥5% loss^[4].

Dimension	Semaglutide	Tirzepatide
Drug class	GLP-1 receptor agonist	Dual GLP-1 / GIP receptor agonist
FDA-approved brand names	Wegovy (weight management), Ozempic (type 2 diabetes)	Zepbound (weight management), Mounjaro (type 2 diabetes)
Pivotal trial, mean weight loss	14.9% at 68 weeks (STEP 1)^[2]	Up to 22.5% at 72 weeks, 15 mg (SURMOUNT-1)^[4]
Head-to-head result	−13.7% at 72 weeks^[5]	−20.2% at 72 weeks^[5]
Most common side effects	Nausea, diarrhea, vomiting, constipation - most common during titration	Same GI profile; SURMOUNT-5 reported a lower discontinuation rate than semaglutide
Dosing frequency	Once weekly, subcutaneous injection	Once weekly, subcutaneous injection
Boxed warning	Thyroid C-cell tumors (rodent data)	Thyroid C-cell tumors (rodent data)
Beema Health cash price	From $99/mo first month, then $174/mo (code sema-off100)	From $199/mo

5.Side-Effect Profile

Both drugs share the same class of side effects, most common during dose titration and usually mild-to-moderate.

Semaglutide (pooled STEP 1-3 data): nausea 43.9% (vs. 16.1% placebo), diarrhea 29.7%, vomiting 24.5%, constipation 24.2%; 99.5% of GI events were non-serious, and 4.3% of patients permanently discontinued due to GI events^[2].
Tirzepatide (SURMOUNT-1): nausea 24.6%-33.3% depending on dose, with GI-related discontinuation under about 8%^[4].
Shared boxed warning: thyroid C-cell tumors, based on rodent data with no confirmed human causation. Both are contraindicated in people with a personal or family history of medullary thyroid carcinoma or MEN 2. Rarer risks for both include pancreatitis and gallbladder events.

6.Dosing and Administration (Educational Only)

Semaglutide: FDA labeling starts at 0.25 mg once weekly and escalates roughly every 4 weeks (0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg), reaching the 2.4 mg maintenance dose around week 17. The 0.25 mg starting dose is explicitly a tolerability dose, not a therapeutic one.
Tirzepatide: a structured, slower dose escalation to a maximum tolerated dose, commonly 10 mg or 15 mg once weekly, following a “start low, go slow” schedule.

Both escalation schedules exist specifically to reduce the risk of gastrointestinal side effects, which are most common during and shortly after each dose increase.

7.Cost Comparison

Wegovy (semaglutide) brand list price: roughly $1,349 per 28-day package. Ozempic (semaglutide, diabetes indication) lists around $1,028.
Zepbound (tirzepatide) brand list price: roughly $1,086/month.
Both manufacturers run cash-pay savings programs for eligible self-pay patients at meaningfully lower prices than list - see each manufacturer's site for current terms.
Compounded, cash-pay (Beema Health): compounded semaglutide from $99/mo the first month (then $174/mo, code sema-off100); compounded tirzepatide from $199/mo. Compounded medications are prepared by a licensed pharmacy rather than manufactured and FDA-approved as a finished product, and are not therapeutically equivalent to the branded version - they are typically the lowest-cost cash-pay path when clinically appropriate and legally available, not a claim of being the same product.

8.Which One Is Right for You?

This is not a decision a comparison page can make. A licensed provider weighs your medical history, current medications, tolerance for GI side effects, cost, and goals before recommending either drug - or neither. Some patients start on one and switch based on how they respond; that, too, is a clinical call, not a self-directed one.

Want the fuller picture first, including how either compares to traditional lifestyle-only weight loss? Read the full GLP-1 research guide.

9.Frequently Asked Questions

Is tirzepatide more effective than semaglutide?

In the SURMOUNT-5 head-to-head trial, tirzepatide produced greater average weight loss than semaglutide (20.2% vs. 13.7% at 72 weeks, P<0.001) and had a lower rate of GI-related discontinuation. That trial was open-label and industry-funded, and it is the only randomized head-to-head comparison. Averages describe trial populations, not individuals - the most appropriate medication for any one person, including whether medication is appropriate at all, is a clinical decision made by a licensed provider.

What's the main difference between semaglutide and tirzepatide?

Semaglutide is a GLP-1 receptor agonist. Tirzepatide is a dual agonist that activates both the GLP-1 receptor and the GIP receptor, a second incretin pathway. That dual mechanism is thought to contribute to tirzepatide's larger average weight-loss effect in trials, though both drugs work primarily by reducing appetite and slowing gastric emptying rather than by directly increasing metabolism.

Do semaglutide and tirzepatide have different side effects?

Both are associated primarily with gastrointestinal side effects - nausea, diarrhea, vomiting, and constipation - most common during dose titration. In pooled STEP 1-3 data, nausea occurred in 43.9% of the semaglutide group vs. 16.1% placebo. In SURMOUNT-1, nausea ranged from 24.6% to 33.3% depending on dose. Both carry an FDA boxed warning for thyroid C-cell tumors (based on rodent data, not confirmed in humans) and are contraindicated with a personal or family history of medullary thyroid carcinoma or MEN 2.

Which is cheaper, semaglutide or tirzepatide?

Brand list prices are broadly similar (Wegovy roughly $1,349/28-day package; Zepbound roughly $1,086/month), though both offer manufacturer cash-pay programs at lower prices for eligible self-pay patients. Compounded versions, when clinically appropriate and legally available, are typically the lowest-cost cash-pay option - see the cost section below for current Beema Health pricing on both.

Can I switch from semaglutide to tirzepatide, or the other way around?

That is a clinical decision that depends on individual response, tolerability, and medical history. It is not something to decide from a comparison page - talk to a licensed provider about whether switching medications makes sense for your situation.

10.References

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