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Side-by-side comparison

Wegovy vs Zepbound

Wegovy contains semaglutide, made by Novo Nordisk. Zepbound contains tirzepatide, made by Eli Lilly. Both brands are approved in the US for chronic weight management. They differ in the molecule inside and in which hormone receptors it acts on.

Last verified 2026-09-29 · how we verify

In plain English

The real difference

  • Wegovy acts on the GLP-1 receptor. Zepbound acts on the GIP receptor and GLP-1 receptor.[src][src]
  • Both are approved medicines.[src][src]
  • Wegovy is made by Novo Nordisk; Zepbound by Eli Lilly.
  • Wegovy is taken as a once-weekly injection or once-daily tablet; Zepbound as a once-weekly injection.
  • Half-life (how long until half the drug has left the blood): Wegovy, about 1 week (elimination half-life); the drug stays in the blood for about 5 weeks after the last injection; Zepbound, about 5 days (5 to 6 days in adults with obesity).[src][src]
  • Our sources include a head-to-head trial of the two molecules. SURMOUNT-5 versus semaglutide: -20.2% with tirzepatide versus -13.7% with semaglutide at 72 weeks (751 adults, open-label).[src]

Which one suits a person is a decision for them and their clinician.

Wegovy and Zepbound, side by side

Wegovy compared with Zepbound
Wegovysemaglutide · Novo NordiskZepboundtirzepatide · Eli Lilly
The basics
MoleculeSemaglutideTirzepatide
Brand namesWegovyZepbound
MakerNovo NordiskEli Lilly
Acts onThe hormone receptors the drug switches onGLP-1 receptorGIP receptor, GLP-1 receptor
Approved to treat
  • Chronic weight management (injection from age 12; tablets in adults); lowering heart-event risk in adults with established heart disease and obesity or overweight (injection and tablets); noncirrhotic MASH with moderate to advanced fibrosis in adults (injection only, accelerated approval)
  • Chronic weight management in adults with obesity, or overweight with a weight-related condition; moderate-to-severe obstructive sleep apnea in adults with obesity (US label)
How it is takenApproved as a once-weekly subcutaneous injection (Ozempic, Wegovy) or as a once-daily oral tablet co-formulated with SNAC (Rybelsus, Ozempic tablets, Wegovy tablets), prescribed and supervised by a clinician.Subcutaneous injection, given once a week, supplied as prefilled pens or vials
Half-lifeHow long until half the drug has left the bloodAbout 1 week (elimination half-life); the drug stays in the blood for about 5 weeks after the last injection[src]About 5 days (5 to 6 days in adults with obesity)[src]
Evidence and safety
Evidence levelSame for both
Approved. Approved by a major regulator after large trials.
Approvals and filings
  • FDA approval, Wegovy. Original FDA approval on 4 June 2021 (injection, chronic weight management).[src]
  • FDA approval for MASH. On 15 August 2025 the FDA granted Wegovy accelerated approval for noncirrhotic MASH with moderate to advanced liver fibrosis; a study to confirm clinical benefit is ongoing.[src]
  • FDA approval for weight management. Approved on 8 November 2023 as Zepbound for chronic weight management in adults with obesity, or overweight with a weight-related condition.[src]
  • FDA approval for sleep apnea. Zepbound approved on 20 December 2024 for moderate-to-severe obstructive sleep apnea in adults with obesity.[src]
Key trial resultsTrials test the molecule, not a brand; each result names its population
  • STEP 1 weight result. Mean weight change at 68 weeks was -14.9% with semaglutide versus -2.4% with placebo (1,961 adults, plus lifestyle intervention).[src]
  • SELECT heart outcomes. Major cardiovascular events occurred in 6.5% on semaglutide versus 8.0% on placebo (hazard ratio 0.80; 17,604 adults with heart disease and overweight or obesity, no diabetes).[src]
  • SURMOUNT-1 weight change at 72 weeks. -20.9% at the highest of three maintenance doses versus -3.1% with placebo (2,539 adults with obesity, or overweight with a weight-related condition, and without diabetes).[src]
  • SURMOUNT-5 versus semaglutide. -20.2% with tirzepatide versus -13.7% with semaglutide at 72 weeks (751 adults, open-label).[src]
Known safety signals
  • Boxed warning: in rodents semaglutide caused dose- and duration-dependent thyroid C-cell tumours at clinically relevant exposures. Whether it does so in humans is unknown. It is contraindicated in people with a personal or family history of medullary thyroid carcinoma or with MEN 2.[src]
  • Gastrointestinal effects are the most common adverse reactions. In the pooled weight-management trials of Wegovy injection versus placebo, nausea occurred in 44% versus 16%, diarrhoea 30% versus 16%, vomiting 24% versus 6% and constipation 24% versus 11%.[src]
  • The label warns of acute pancreatitis, acute gallbladder disease (cholelithiasis in 1.6% of adults on Wegovy injection versus 0.7% on placebo in weight-reduction trials), acute kidney injury from volume depletion, and hypersensitivity reactions.[src]
  • In SUSTAIN-6, diabetic retinopathy complications were higher with semaglutide than placebo (hazard ratio 1.76; 95% CI 1.11 to 2.78) in people with type 2 diabetes at high cardiovascular risk.[src]
  • Because semaglutide delays gastric emptying, there are rare post-marketing reports of pulmonary aspiration during general anaesthesia or deep sedation in people taking GLP-1 receptor agonists.[src]
  • Compounded semaglutide products are not FDA-approved. As of 31 May 2026 the FDA had received 990 adverse-event reports associated with compounded semaglutide. The FDA notes these events are likely underreported, because federal law does not require state-licensed pharmacies that are not outsourcing facilities to report them.[src]
  • Boxed warning: in rats, tirzepatide caused thyroid C-cell tumours at clinically relevant exposures. It is unknown whether it causes these tumours, including medullary thyroid carcinoma, in humans. It is contraindicated in people with a personal or family history of medullary thyroid carcinoma or with Multiple Endocrine Neoplasia syndrome type 2.[src]
  • In SURPASS-2, the most common adverse events with tirzepatide were gastrointestinal and mostly mild to moderate: nausea in 17 to 22%, diarrhoea in 13 to 16% and vomiting in 6 to 10% of the three tirzepatide groups. Serious adverse events were reported in 5 to 7% of tirzepatide patients and 3% of semaglutide patients.[src]
  • US labels list nausea, diarrhoea, vomiting, constipation, abdominal pain and dyspepsia among the most common adverse reactions (5% or more of patients), and warn of serious gastrointestinal reactions (not recommended in severe gastroparesis), acute kidney injury from dehydration, acute gallbladder disease and acute pancreatitis.[src]
  • The label states that the risk of hypoglycaemia, including severe hypoglycaemia, is increased when tirzepatide is used with insulin or an insulin secretagogue such as a sulfonylurea.[src]
  • Because it delays gastric emptying, tirzepatide can affect the absorption of oral medicines, and there are rare postmarketing reports of pulmonary aspiration in people taking GLP-1 receptor agonists who had elective procedures under general anaesthesia or deep sedation.[src]
  • Other label warnings include serious hypersensitivity reactions (anaphylaxis, angioedema) reported after marketing, monitoring for diabetic retinopathy complications in people with type 2 diabetes and a history of retinopathy, and possible fetal harm in pregnancy.[src]
Legal status
United States
Approved

FDA-approved as Ozempic, Rybelsus and Wegovy; compounded copies lost their shortage cover in 2025 and 503B is proposing a formal exclusion[src]

Full detail →
Approved

FDA-approved as Mounjaro (type 2 diabetes) and Zepbound (weight management, sleep apnea); shortage over since December 2024[src]

Full detail →
United Kingdom
Approved

Licensed in the UK: Ozempic and Rybelsus for type 2 diabetes, Wegovy for weight management (now also as a tablet)[src]

Full detail →
Approved

Licensed in the UK as Mounjaro for type 2 diabetes and for weight management; NHS access is being phased in[src]

Full detail →
European Union
Approved

Authorised EU-wide for type 2 diabetes, weight management and MASH (Ozempic, Rybelsus, Wegovy, Kayshild)[src]

Full detail →
Approved

Authorised EU-wide as Mounjaro for type 2 diabetes and for weight management in adults[src]

Full detail →
Australia
Approved

Approved on the ARTG as Ozempic, Rybelsus and Wegovy. PBS covers Ozempic for type 2 diabetes; Wegovy is not yet PBS-listed. Compounded copies barred since 1 Oct 2024.[src]

Full detail →
Approved

Approved as Mounjaro for type 2 diabetes (Dec 2022) and weight management (Sep 2024). Not PBS-listed: the sponsor is not proceeding for now. Compounding barred since Oct 2024.[src]

Full detail →
Canada
Generics available

Approved as Ozempic, Rybelsus and Wegovy; generic semaglutide approved from April 2026 and on sale since May 2026[src]

Full detail →
Approved

Approved as Mounjaro (type 2 diabetes) and Zepbound (weight management, sleep apnea); no generic submissions[src]

Full detail →

Trial results come from separate studies unless a row says it is a head-to-head trial. Populations, durations and methods differ, so compare numbers across columns with care.

Go deeper

Molecule

Semaglutide explained →Watch the 3D body journey →

Molecule

Tirzepatide explained →Watch the 3D body journey →

Educational information only. Not medical advice, not a recommendation to use any substance, and not an offer to supply. Talk to a licensed clinician about your own care.

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