Mounjaro vs Ozempic

Summary: Mounjaro (tirzepatide) beat Ozempic (semaglutide) on A1C and weight loss in the SURPASS-2 head-to-head trial, but Ozempic has the SELECT cardiovascular outcomes data that Mounjaro does not yet have.

This content is for informational purposes only and is not medical advice. Always consult a qualified healthcare provider before starting, changing, or stopping any medication.

The short version: Mounjaro is tirzepatide, a dual GIP and GLP-1 receptor agonist. Ozempic is semaglutide, a GLP-1 only agonist. In the only head-to-head trial that has been run between them, SURPASS-2, Mounjaro produced larger A1C drops and larger weight loss than Ozempic at every dose tested ^[1]. Ozempic has something Mounjaro does not: a finished cardiovascular outcomes trial (SELECT) that showed a 20% reduction in major adverse cardiac events in people with obesity and established heart disease ^[2].

That tradeoff is the entire decision tree. If the goal is the biggest A1C and weight number, Mounjaro has the data. If the goal includes documented cardiovascular protection in someone who already has heart disease, Ozempic has the label.

The same drug class, two different molecules

Both Mounjaro and Ozempic are once-weekly subcutaneous injections approved by the FDA for type 2 diabetes. Neither is approved by the FDA for weight loss on its own. The weight loss approvals belong to their sister drugs: Zepbound (tirzepatide, same molecule as Mounjaro) and Wegovy (semaglutide, same molecule as Ozempic). When people compare "Mounjaro for weight loss" against "Ozempic for weight loss," they are comparing off-label prescribing of two diabetes drugs, and the underlying molecules are the same as the approved weight loss versions at the same doses.

The dosing numbers look different but they are not directly comparable. Tirzepatide and semaglutide are different molecules and 1 mg of one does not equal 1 mg of the other any more than 1 mg of caffeine equals 1 mg of nicotine. Compare the drugs on what they do, not on the milligram number on the label.

Mechanism: dual receptor versus single receptor

Ozempic activates the GLP-1 receptor. That single mechanism slows gastric emptying, increases satiety, suppresses glucagon release after meals, and stimulates insulin release in a glucose-dependent way. The cumulative effect is lower blood sugar and lower appetite.

Mounjaro activates both the GLP-1 receptor and the GIP receptor. GIP (glucose-dependent insulinotropic polypeptide) is the other major incretin hormone the gut releases after meals. The dual mechanism layers GIP's metabolic effects on top of the GLP-1 effects, and in trials it consistently produces larger reductions in A1C and weight than GLP-1 alone.

Whether GIP's contribution is additive, synergistic, or whether GIP modifies GLP-1's downstream signaling is still being worked out in the literature. What is settled is the clinical readout: the dual agonist hits harder than the single agonist at maximum doses.

SURPASS-2: the head-to-head trial that matters

SURPASS-2 is the only published phase 3 trial that compares tirzepatide directly against semaglutide in the same patient population ^[1]. It enrolled 1,879 adults with type 2 diabetes inadequately controlled on metformin, and randomized them to four arms for 40 weeks:

• Tirzepatide 5 mg weekly
• Tirzepatide 10 mg weekly
• Tirzepatide 15 mg weekly
• Semaglutide 1 mg weekly

Note the semaglutide dose. SURPASS-2 used 1 mg, which was the highest Ozempic dose approved at the time the trial was designed. The 2 mg dose was approved later. So the head-to-head data does not directly answer "tirzepatide 15 mg versus semaglutide 2 mg," and that gap is the single biggest caveat when reading the trial results.

Every tirzepatide dose beat semaglutide 1 mg on A1C and on weight, and the difference grew at the higher doses. The 15 mg arm dropped almost twice as much body weight as the semaglutide arm in absolute kilograms.

A1C reduction in practice

In the real world, A1C drops from tirzepatide tend to track the trial numbers closely. Patients on Mounjaro 10 mg or 15 mg routinely move from A1C above 8% to below 6.5% over six to nine months. Ozempic moves people too, just less. The maximum effect from Ozempic 2 mg, which was not in SURPASS-2, has been measured in SUSTAIN FORTE and similar trials at roughly -2.1% A1C, which closes some of the gap to tirzepatide 5 mg but does not catch the 10 or 15 mg arms.

For an endocrinologist trying to get a patient out of poorly controlled diabetes, the calculus is simple. If the patient has not yet tried an incretin agonist and their A1C is stubbornly high, the tirzepatide arm is more likely to hit target. If the patient is already on Ozempic and well controlled, the case for switching is weaker.

Weight loss as a secondary outcome

Weight loss was a secondary endpoint in SURPASS-2, not the primary outcome. But because both drugs are now widely prescribed off-label for weight loss, the weight numbers from the trial are what most patients are searching for.

At 40 weeks, tirzepatide 15 mg patients lost an average of 11.2 kg (about 24.7 lb). Semaglutide 1 mg patients lost 5.7 kg (about 12.6 lb). Roughly double. At the lowest tirzepatide arm (5 mg) the loss was still 7.6 kg, beating semaglutide 1 mg by nearly two kilograms.

The picture changes when you add the obesity-specific trials. SURMOUNT-1 ran tirzepatide on people with obesity but without diabetes and saw roughly 20% body weight loss at 72 weeks on 15 mg. STEP 1 ran semaglutide 2.4 mg (the Wegovy dose) on the same population and saw roughly 15% body weight loss at 68 weeks. Different trials, different patient populations, different durations, but the relative gap holds: the tirzepatide molecule produces more weight loss than the semaglutide molecule at maximum doses.

Side effect profile

Both drugs share the GI side effect cluster that comes with all incretin agonists: nausea, vomiting, diarrhea, constipation, abdominal pain, and reduced appetite. The mechanism is slowed gastric emptying, which is also part of how the drugs work for weight loss, so the side effect and the desired effect share a pathway.

In SURPASS-2, the GI adverse event rates were broadly similar between tirzepatide and semaglutide, with a slight signal toward higher nausea and vomiting at the tirzepatide 15 mg dose ^[1]. The discontinuation rates from adverse events ran 6.0% on tirzepatide 5 mg, 8.4% on 10 mg, 8.6% on 15 mg, and 4.1% on semaglutide. So a higher tirzepatide dose does push more patients out of the trial, but the absolute numbers stay in single digits.

Both labels carry a boxed warning for thyroid C-cell tumors, based on rodent data ^[3][4]. Neither has been linked to thyroid cancer in human trials, but both are contraindicated in people with a personal or family history of medullary thyroid carcinoma or MEN2.

Pancreatitis appears as a rare adverse event on both labels. Gallbladder disease, including gallstones and acute cholecystitis, has been reported with both, with rates that climb at higher doses and faster weight loss. Diabetic retinopathy worsening showed up in semaglutide's SUSTAIN-6 trial and remains on the Ozempic label as a precaution for people with pre-existing retinopathy ^[5].

Cardiovascular outcomes: the area where Ozempic has the data

This is the biggest non-obvious difference between the two drugs.

Semaglutide has finished two large cardiovascular outcomes trials. SUSTAIN-6 enrolled 3,297 people with type 2 diabetes and high cardiovascular risk and showed a 26% reduction in the primary MACE composite (cardiovascular death, non-fatal MI, non-fatal stroke) over a median of 2.1 years ^[5]. SELECT enrolled 17,604 people with obesity and pre-existing cardiovascular disease but no diabetes, and showed a 20% reduction in the primary MACE composite over a mean of 39.8 months ^[2]. SELECT is the trial that put a cardiovascular indication on the Wegovy label.

Tirzepatide does not yet have a published cardiovascular outcomes trial. SURPASS-CVOT is ongoing and is expected to read out in 2027. Until then, Mounjaro's label does not include a cardiovascular benefit claim, and prescribers who want documented CV protection have to use Ozempic, Trulicity, or a similar GLP-1 with an established outcomes trial.

For a patient with established atherosclerotic cardiovascular disease, this matters. The evidence-based prescribing guideline from the ADA and the AHA puts a GLP-1 with proven cardiovascular benefit at the top of the second-line list after metformin, specifically for this population. As of 2026, Mounjaro does not satisfy that criterion. Ozempic does.

Cost: list prices are similar, real prices vary

Both drugs sit at a US list price of roughly $1,000 to $1,100 per month for the highest doses. That number is almost never what anyone pays.

The manufacturer savings cards from Lilly (Mounjaro) and Novo Nordisk (Ozempic) cut copays to around $25 per month for commercially insured patients with the right diagnosis on the prescription. They do not work for Medicare or Medicaid patients. They have eligibility caps that change every year.

In the UK, both drugs are available on the NHS for type 2 diabetes that has not responded to standard therapy, and both are available privately. NHS cost-effectiveness analyses have generally come out in favor of tirzepatide at higher BMI thresholds because the larger weight loss per pound spent shifts the QALY math. Private UK pricing for Mounjaro and Ozempic runs broadly in line with each other, in the £150 to £250 per month range depending on dose and pharmacy.

Insurance coverage in the US

For type 2 diabetes, both drugs are typically covered by commercial insurance and many Medicare Part D plans, often with prior authorization. The PA forms usually require documented metformin trial, A1C above a threshold, and sometimes a body weight criterion.

For off-label weight loss, neither drug is covered by most insurance plans. This is the single biggest reason patients end up on compounded tirzepatide or compounded semaglutide instead of the brand pens. The brand pen runs $1,000 a month cash, and a compounded multi-dose vial runs $200 to $400 a month for an equivalent dose.

Medicare currently does not cover any GLP-1 or dual incretin agonist purely for weight loss. The CMS rules require a diabetes or cardiovascular indication for coverage. The 2024 SELECT readout opened the door for Wegovy to be covered for cardiovascular risk reduction in people with obesity and pre-existing heart disease, and CMS announced limited coverage under that indication in 2024. The same indication does not yet exist for Mounjaro or Zepbound.

Switching from Ozempic to Mounjaro

This is a common move once a patient has been on Ozempic for six to twelve months and either plateaued on weight loss or wants larger A1C reduction.

There is no formal washout period between the two drugs. They have similar half-lives (roughly five to seven days) and similar receptor pharmacology on the GLP-1 side. Most clinicians stop the last Ozempic dose and start Mounjaro 2.5 mg one week later, then titrate Mounjaro on its normal four-week ladder up to the target dose.

Two practical notes about the switch. First, do not assume that being on Ozempic 1 mg means you can start Mounjaro at 5 mg. The titration ladder exists for GI tolerability, not for receptor adaptation, and many people who tolerate Ozempic 1 mg get hit hard by Mounjaro 5 mg if they skip the 2.5 mg starter month. Second, your A1C and weight will probably drift up a little during the titration window. That is normal. Plan with your prescriber so you do not panic over a four-week interim bump.

Compounded tirzepatide vs Ozempic

Compounded tirzepatide and compounded semaglutide both exploded during the 2023 to 2025 brand shortages. The FDA's policy is that compounding is permitted when a drug is on the official shortage list, and both tirzepatide and semaglutide have moved on and off that list as Lilly and Novo Nordisk scaled up brand production. As of 2026, tirzepatide is technically off the FDA shortage list while semaglutide remains in a more complicated status with continued compounding allowed in some regulatory niches.

For a cash-pay patient choosing between compounded tirzepatide and brand Ozempic, the math is approximately: $250 a month for compounded tirzepatide at clinical doses versus $1,000 a month for brand Ozempic. Both can be reasonable choices. Brand Ozempic has the FDA quality controls and the documented cardiovascular benefit. Compounded tirzepatide has the larger A1C and weight loss data behind the molecule, at a quarter of the price, with the tradeoff that the specific compounded product has not been through FDA approval.

Who Mounjaro is better for

• Type 2 diabetes patients with A1C significantly above goal who want the largest A1C drop achievable from a single weekly injection.
• Patients with both type 2 diabetes and obesity, where the weight loss tail of the response curve is part of the treatment plan.
• Patients who have been on Ozempic for several months and have plateaued on either glucose control or weight loss.
• People on the diabetes-only label who do not have established cardiovascular disease, so the missing CV outcomes data is not a deciding factor.

Who Ozempic is better for

• Type 2 diabetes patients with established atherosclerotic cardiovascular disease, where the SUSTAIN-6 CV benefit is part of the indication for prescribing.
• Patients with obesity and established heart disease who would qualify for the SELECT-based Wegovy indication. Ozempic is the same molecule and the same dose at the 2.4 mg level.
• Patients who have tolerated semaglutide well, have hit their A1C and weight goals, and have no clinical reason to switch.
• Patients in regions or insurance plans where Ozempic is on formulary and Mounjaro is not, since starting on the available drug always beats not starting.

What this comparison does not decide

This page compares the two drugs on the data. It does not decide whether you should be on a GLP-1 or dual agonist at all. That decision depends on your A1C history, your weight history, what other diabetes drugs you have tried, your kidney function, your history of pancreatitis, your thyroid history, and a dozen other variables your prescriber knows. The trial numbers on this page are population averages. Your response will sit somewhere in that distribution, and the only way to find out where is to start, titrate, and measure.

Frequently asked questions

Is Mounjaro the same as Ozempic?

No. Mounjaro is tirzepatide, a dual GIP and GLP-1 agonist made by Lilly. Ozempic is semaglutide, a GLP-1 agonist made by Novo Nordisk. Different molecules, different mechanisms, different manufacturers.

Which is better for weight loss, Mounjaro or Ozempic?

At maximum doses, Mounjaro produces more weight loss. SURPASS-2 showed roughly twice the weight loss at tirzepatide 15 mg compared with semaglutide 1 mg over 40 weeks. The pattern holds in obesity-specific trials of the sister drugs Zepbound and Wegovy.

Which has more A1C reduction in type 2 diabetes?

Mounjaro. SURPASS-2 measured A1C drops of about 2.30% on tirzepatide 15 mg versus 1.86% on semaglutide 1 mg at 40 weeks. Every tirzepatide arm beat semaglutide 1 mg.

How much do Mounjaro and Ozempic cost compared with each other?

List prices are similar, roughly $1,000 to $1,100 per month in the US. With commercial insurance plus manufacturer savings cards, both can be as low as $25 a month. Without insurance, cash prices are similar.

What about Mounjaro vs Ozempic cost UK?

Both are available on the NHS for type 2 diabetes with prior authorization criteria, and both are available privately in the £150 to £250 per month range depending on dose and pharmacy. NICE has issued favorable cost-effectiveness analyses for tirzepatide at higher BMI thresholds.

Do they have the same side effects?

Largely yes. Nausea, vomiting, diarrhea, constipation, and reduced appetite are common with both. SURPASS-2 showed slightly higher GI rates and slightly higher discontinuation at tirzepatide 15 mg compared with semaglutide 1 mg. Both carry the same boxed warning for thyroid C-cell tumors.

Does Mounjaro have cardiovascular outcomes data?

Not yet. SURPASS-CVOT is ongoing and is expected to read out in 2027. Until then, Mounjaro's label does not include a cardiovascular benefit claim, and prescribers who want documented CV protection use a GLP-1 with proven outcomes such as Ozempic.

Can I switch from Ozempic to Mounjaro?

Yes, and it is a common move once Ozempic plateaus. Most clinicians stop the last Ozempic dose, wait one week, and start Mounjaro at 2.5 mg, then titrate up on the standard four-week ladder. Do not skip the 2.5 mg starter dose.

Are tirzepatide and semaglutide the same thing as Mounjaro and Ozempic?

Tirzepatide is the generic name of Mounjaro and Zepbound. Semaglutide is the generic name of Ozempic, Wegovy, and Rybelsus. The molecule is the same across brand names made by the same manufacturer; the brand differs only in indication, dosing, and packaging.

Is compounded tirzepatide the same as Ozempic?

No. Compounded tirzepatide is the same molecule as Mounjaro and Zepbound, prepared by a compounding pharmacy. Ozempic is brand semaglutide. The two are different drugs with different mechanisms, different doses, and different prices.

Which is better for type 2 diabetes with heart disease?

Ozempic, because of the SUSTAIN-6 and SELECT cardiovascular outcomes trial data. Mounjaro is likely effective in this population too based on shared mechanism, but the proof has not been published.