Semaglutide vs Tirzepatide
The two molecules behind every major GLP-1 weight-loss brand. One is a single GLP-1 agonist (Ozempic, Wegovy, Rybelsus); the other adds a second hormone (Mounjaro, Zepbound). Here’s how they compare on weight loss, cost, dosing and side effects — based on the clinical trials, with sources.
The short answer
Tirzepatide produces more weight loss than semaglutide. In SURMOUNT-5, the first head-to-head trial, tirzepatide led to 20.2% average body-weight reduction versus 13.7% for semaglutide at 72 weeks — a 47% greater relative loss (NEJM, 2025). Semaglutide, however, is the only one of the two FDA-approved to reduce heart-attack and stroke risk, and the only one with an oral form (Rybelsus).
Which brand is which?
Both molecules are sold under several brand names. The active ingredient — not the brand — is what determines how the drug works. Full breakdown of each: semaglutide and tirzepatide.
Semaglutide
Single GLP-1 receptor agonist · Novo Nordisk
Sold as: Ozempic (T2D), Wegovy (obesity), Rybelsus (oral T2D)
Tirzepatide
Dual GIP + GLP-1 receptor agonist · Eli Lilly
Sold as: Mounjaro (T2D), Zepbound (obesity)
Semaglutide vs tirzepatide: side by side
| Factor | Semaglutide | Tirzepatide |
|---|---|---|
| Drug class | Single GLP-1 receptor agonist | Dual GIP + GLP-1 receptor agonist |
| Brand names | Ozempic (T2D), Wegovy (obesity), Rybelsus (oral T2D) | Mounjaro (T2D), Zepbound (obesity) |
| Weight loss (pivotal trial) | 14.9% at 68 weeks (STEP-1, Wegovy 2.4 mg) | 20.9% at 72 weeks (SURMOUNT-1, 15 mg) |
| Weight loss (head-to-head, SURMOUNT-5) | 13.7% at 72 weeks | 20.2% at 72 weeks |
| How it’s taken | Weekly injection (Ozempic/Wegovy) or daily pill (Rybelsus) | Weekly injection |
| Heart-disease benefit | FDA-approved to cut heart-attack/stroke risk (Wegovy, SELECT trial) | Cardiovascular-outcomes trial (SURMOUNT-MMO) still ongoing |
| Cost without insurance | List ~$1,000–$1,349/mo; cash-pay from ~$349/mo (NovoCare vials; $199 intro) | List ~$1,000–$1,400/mo; Lilly self-pay from $299/mo (2.5 mg), rising to $699/mo at maintenance doses |
| Maker | Novo Nordisk | Eli Lilly |
Trial figures are mean weight loss from each drug’s pivotal Phase 3 study and the SURMOUNT-5 head-to-head; individual results vary. Prices are estimates as of June 2026 and change without notice. See sources below.
Which is right for you?
Tirzepatide may fit if: maximum weight loss is the priority, you’re comfortable with a weekly injection, and cost/coverage works — it delivered the larger reduction in the head-to-head trial.
Semaglutide may fit if: you also want documented heart-attack/stroke risk reduction (Wegovy), prefer the option of a daily pill (Rybelsus), or value the longer real-world track record.
Either way: insurance coverage, the manufacturer savings card and cash-pay price often matter more than the molecule. Compare the specific brands and current prices before deciding.
Compare the specific brands
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Not medical advice
This comparison is educational. Both medications are prescription-only and carry a boxed warning for thyroid C-cell tumors. The choice between semaglutide and tirzepatide — and the decision to switch — should be made with a licensed clinician based on your health history, other conditions, insurance and goals. GLP1Zoom is an independent comparison site, not a pharmacy or prescriber.
Common questions about Semaglutide vs Tirzepatide
Is tirzepatide better than semaglutide for weight loss?
In SURMOUNT-5 — the first head-to-head randomized trial (NEJM, 2025) — tirzepatide produced 20.2% average weight loss versus 13.7% for semaglutide over 72 weeks, a 47% greater relative reduction. So on weight loss alone the trial data favor tirzepatide. "Better" overall still depends on the goal: semaglutide (as Wegovy) is FDA-approved to lower heart-attack and stroke risk and offers an oral option (Rybelsus), while tirzepatide’s cardiovascular-outcomes trial is still ongoing. This is not medical advice — the right drug is the one your prescriber selects for your health profile.
Is Zepbound the same as Ozempic?
No. Zepbound is tirzepatide (a dual GIP + GLP-1 agonist made by Eli Lilly); Ozempic is semaglutide (a single GLP-1 agonist made by Novo Nordisk). They are different molecules from different companies. Zepbound is FDA-approved for weight management; Ozempic is approved for type 2 diabetes. The semaglutide product approved for weight loss is Wegovy, not Ozempic.
Which has fewer side effects, semaglutide or tirzepatide?
Both cause similar gastrointestinal side effects — nausea, diarrhea, vomiting and constipation — that are usually mild-to-moderate and ease as the dose is increased slowly. In SURMOUNT-5 the side-effect profiles were broadly comparable and discontinuation rates were low for both. Both carry the same boxed warning about thyroid C-cell tumors seen in rodents. There is no clear "gentler" molecule; tolerability varies person to person.
Can you switch from semaglutide to tirzepatide?
Many people do switch, often for greater weight loss or because of cost, coverage or side effects — but it must be done under a prescriber’s guidance, who will restart dosing at the lowest tirzepatide step rather than matching your semaglutide dose. We are an independent comparison site and cannot prescribe or advise on switching; talk to your clinician.
Is tirzepatide more expensive than semaglutide?
List prices are similar — roughly $1,000–$1,400 a month without insurance for both as of June 2026. For cash-pay patients the single-dose vial programs have narrowed the gap: Eli Lilly’s LillyDirect Zepbound vials start around ~$299/month and Novo Nordisk’s NovoCare Wegovy vials around $349/month. Prices change often — confirm current pricing with the manufacturer or a provider before buying.
Sources
- Aronne LJ, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5). N Engl J Med. 2025. DOI: 10.1056/NEJMoa2416394 — head-to-head: tirzepatide 20.2% vs semaglutide 13.7% at 72 weeks.
- Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP-1). N Engl J Med. 2021; semaglutide 2.4 mg → 14.9% at 68 weeks. DOI: 10.1056/NEJMoa2032183.
- Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022; tirzepatide 15 mg → 20.9% at 72 weeks. DOI: 10.1056/NEJMoa2206038.
- FDA prescribing information for Wegovy, Ozempic, Rybelsus, Zepbound and Mounjaro; manufacturer cash-pay programs (NovoCare, LillyDirect) as of June 2026.
Last reviewed 2026-06-26. Figures change as new trials publish and prices update — verify current pricing and FDA labeling before making decisions.