Side-by-side
| Ozempic | Mounjaro | |
|---|---|---|
| Active drug | Semaglutide | Tirzepatide |
| Drug class | GLP-1 agonist | Dual GIP + GLP-1 agonist |
| FDA-approved for | Type 2 diabetes (+ CV risk) | Type 2 diabetes |
| A1C drop (SURPASS-2) | −1.9 pts (1 mg) | −2.1 to −2.5 pts |
| Weight loss (SURPASS-2) | −6.2 kg (1 mg) | −7.8 to −12.4 kg |
| Weight-loss version | Wegovy | Zepbound |
The head-to-head trial (SURPASS-2)
SURPASS-2 (New England Journal of Medicine, 2021) randomized 1,879 adults with type 2 diabetes on metformin to tirzepatide (5, 10, or 15 mg) or semaglutide 1 mg, once weekly for 40 weeks. All three tirzepatide doses were superior on both HbA1c (−2.1 to −2.5 points vs −1.9) and weight (−7.8 to −12.4 kg vs −6.2 kg). It is the only direct comparison of these two molecules in diabetes.
The caveat headlines skip
The comparator was semaglutide 1 mg— Ozempic's maximum approved dose in 2021. The 2 mg Ozempic dose (approved 2022) and Wegovy's 2.4 mg were not in the trial. So SURPASS-2 shows tirzepatide beat semaglutide 1 mg, not semaglutide at its highest doses. “Mounjaro wins” is true for that comparison — just not the whole story.
Neither is a weight-loss drug (on paper)
People lose weight on both, but Ozempic and Mounjaro are FDA-approved to treat type 2 diabetes, not obesity. The same molecules are approved for weight loss under different brands and doses — Wegovy (semaglutide 2.4 mg) and Zepbound (tirzepatide). If weight loss is the goal, see our Zepbound vs Wegovy comparison (which has its own direct head-to-head trial), and the ingredient hubs for semaglutide and tirzepatide.
The practical differences nobody mentions until you're using it
Trial results decide which drug is more effective on average. These decide what living with it is like — and they differ more than most comparisons admit.
| Ozempic | Mounjaro | |
|---|---|---|
| In-use storage | Up to 56 days after first use | Up to 21 days after first use |
| Pen type | Multi-dose pen | Single-dose pen or vial |
| If you miss a dose | Take within 5 days, then resume schedule | Take within 4 days, then resume schedule |
| Changing your dose day | Leave at least 48 hours between doses | Leave at least 72 hours between doses |
| List price | $969–$998/mo | $1,069/mo |
The storage gap is the one that catches people out: 56 days versus 21 changes how you travel and what happens to a pen left out. Details: Ozempic storage · missed dose · changing your dose day. Always follow your own product's instructions — these windows are drug-specific, not interchangeable.
Side effects: similar profile, different intensity curve
Both are dominated by gastrointestinal effects — nausea, diarrhea, vomiting, constipation — concentrated during dose escalation and easing for most people once a dose is held steady. Both carry a boxed warning about thyroid C-cell tumors and are contraindicated in people with a personal or family history of medullary thyroid carcinoma or MEN 2. Both carry pancreatitis and gallbladder warnings.
The honest nuance: in the head-to-head trial, the drug that produced more weight loss and more A1C reduction also produced somewhat more gastrointestinal effects. Discontinuation rates for adverse events were low and broadly comparable, but “more effect” and “more nausea” tend to travel together. If you titrate slowly and tolerate it, that trade is usually worth it; if you don't, the more effective drug on paper can be the worse drug for you in practice.
Which one fits your situation?
| If this is you | Worth raising with your clinician |
|---|---|
| Type 2 diabetes with established heart disease | Ozempic carries a cardiovascular-risk-reduction indication; that on-label difference matters here |
| Need the largest A1C and weight effect | Tirzepatide won the head-to-head — against semaglutide 1 mg, not its highest doses |
| Struggled with nausea before | Slower titration matters more than which molecule; discuss the escalation plan, not just the drug |
| Travel often or store pens outside a fridge | The 56-day vs 21-day in-use window is a real, practical difference |
| Weight loss is the actual goal | Neither is on-label — Wegovy and Zepbound are, and coverage follows the label |
| Your plan prefers one over the other | Formulary position often decides this in practice; an exception is possible if the preferred one fails you |
Coverage routes: Ozempic PA · Mounjaro PA · formulary exceptions.
Switching between them
Switching is common — usually because of formulary changes, side effects, or an inadequate response — and it is a clinical decision, not a dose conversion you can do yourself. There is no published equivalence table mapping a semaglutide dose onto a tirzepatide dose, because the drugs have different mechanisms and different dose ladders. In practice a switch typically means restarting titration on the new drug rather than jumping to a matching strength.
Two things worth knowing before you ask: expect the early-titration side effects again, since your body is adjusting to a new escalation; and confirm coverage for the new drug before stopping the old one, because an unapproved switch can leave you with a gap. If the switch is being forced by your plan rather than chosen, that is a formulary issue with its own remedy.
Both are prescription drugs with real risks (including a boxed thyroid-tumor warning). This page is educational, dated 2026-07-18, and not medical advice — the right choice depends on your diabetes, heart risk, tolerance, and coverage, decided with a clinician.