Ozempic vs Mounjaro

Weight loss

The two molecules have been compared directly twice. The first trial used Ozempic and Mounjaro doses in people with diabetes. The second used the higher Wegovy and Zepbound doses in people with obesity. Mounjaro’s molecule won both.

At diabetes doses. 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. Mean starting weight was 93.7 kg.

At weight-loss doses. SURMOUNT-5 randomised 751 adults with obesity and no diabetes to the maximum tolerated dose of either molecule for 72 weeks. The semaglutide arm used 1.7 or 2.4 mg, which are Wegovy doses, above Ozempic’s 2 mg ceiling. The tirzepatide arm used 10 or 15 mg, which Mounjaro and Zepbound share.

The gap held at every threshold: more tirzepatide participants lost 10%, 15%, 20%, and 25% of their body weight. The same trial is covered from the obesity-brand side on Wegovy vs Zepbound.

Neither is approved for weight loss

This is the part the search results leave out. Ozempic and Mounjaro are type 2 diabetes labels. The identical molecules are sold for weight reduction as Wegovy and Zepbound, with separate trials and, for semaglutide, higher doses: Wegovy goes to 2.4 mg and, for weight reduction in adults, 7.2 mg. In STEP UP, 7.2 mg produced 18.7% weight loss over 72 weeks, which narrows the gap to tirzepatide’s 20.9% in SURMOUNT-1, though those are separate trials and no head-to-head at 7.2 mg exists.

Each company sells the same molecule under two names so each label carries only the indications its own trials support, and so insurers can cover one and not the other. For someone whose goal is weight, the relevant comparison is Wegovy vs Zepbound. Whether any of the four is prescribed, and which, is a prescriber’s decision and often a coverage question.

Blood sugar

SURPASS-2’s primary endpoint was HbA1c, and tirzepatide won that too.

The estimated difference at 15 mg was 0.45 points. The same caveat applies: semaglutide was tested at 1 mg, and Ozempic 2 mg 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 the chart shows and its exact size is unknown. Clinically significant hypoglycemia was rare on both: 0.2% to 1.7% on tirzepatide, 0.4% on semaglutide.

Heart and kidneys

This is where Ozempic pulls ahead. It has two placebo-controlled outcomes trials; Mounjaro’s molecule has one active-comparator trial for heart attack and stroke, and one placebo-controlled trial in heart failure with preserved ejection fraction, SUMMIT, that is not on the label.

SUSTAIN-6 gave Ozempic its cardiovascular indication: 26% fewer major events than placebo, driven mostly by stroke. FLOW gave it a kidney indication: in 3,533 people with type 2 diabetes and chronic kidney disease, semaglutide cut the composite of kidney failure, a sustained 50% fall in eGFR, kidney death, and cardiovascular death by 24% and reduced death from any cause by 20%.

SURPASS-CVOT tested tirzepatide against dulaglutide, an active drug already shown to reduce events, and found it non-inferior with a hazard ratio of 0.92. That earned Mounjaro a cardiovascular indication, but the size of tirzepatide’s benefit over no treatment has not been measured. Mounjaro has no kidney indication.

The dose ladders

Both hold each step at least four weeks and escalate only if glucose control calls for it. The milligrams are not comparable across the two molecules, and no label offers a conversion.

What is identical

The safety sections. Both labels open with the boxed warning on thyroid C-cell tumors, both are contraindicated with a personal or family history of medullary thyroid carcinoma or MEN 2, and both carry the same warnings on pancreatitis, gallbladder disease, severe gastrointestinal reactions, hypoglycemia with insulin or sulfonylureas, and diabetic retinopathy complications. One difference sits in the drug-interactions section: the Mounjaro 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 Ozempic label has no such instruction.

Which comparison you wanted

• The weight-loss brands, same molecules, higher semaglutide doses: Wegovy vs Zepbound.
• The molecules across both indications: semaglutide vs tirzepatide.
• The cross-brand question: Zepbound vs Ozempic.
• Why Ozempic and Wegovy are one drug: Ozempic vs Wegovy.
• Why Mounjaro and Zepbound are one drug: Zepbound vs Mounjaro.

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

8. Ozempic vs Mounjaro FAQ

• Which causes more weight loss, Ozempic or Mounjaro?

  Mounjaro. In SURPASS-2, adults with type 2 diabetes lost 7.6, 9.3, and 11.2 kg on tirzepatide 5, 10, and 15 mg over 40 weeks, against 5.7 kg on semaglutide 1 mg. In SURMOUNT-5, at the higher doses sold as Zepbound and Wegovy, adults with obesity lost 20.2% versus 13.7% over 72 weeks. Weight reduction is not on either label.

• Can I get Ozempic or Mounjaro for weight loss?

  Neither label includes weight reduction. The same molecules are approved for that as Wegovy and Zepbound, and Wegovy's doses go higher than Ozempic's. Prescribing any of them, and for what, is a prescriber's decision and often a coverage question.

• Is Mounjaro better than Ozempic for diabetes?

  In SURPASS-2, tirzepatide beat semaglutide 1 mg on HbA1c at every dose. Ozempic now goes to 2 mg, which lowered HbA1c by 2.2 points against 1.9 for 1 mg in SUSTAIN FORTE, and no trial has tested 2 mg against tirzepatide. Ozempic also has placebo-controlled cardiovascular and kidney outcome trials that Mounjaro does not.

• Can I switch from Ozempic to Mounjaro?

  Switching between molecules is a prescriber decision. There is no conversion table; each label starts at its own first step, 2.5 mg for Mounjaro and 0.25 mg for Ozempic. Neither label addresses switching from the other.

• Which one 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 ran 17% to 22% on tirzepatide and 18% on semaglutide. Hypoglycemia was rare on both. Semaglutide has five more years of post-marketing data.

9. Sources