Wegovy vs Zepbound
How Wegovy and Zepbound differ on molecule, dose, schedule and what they are licensed for.
The two weight-management flagships. Same practical routine, different molecule, and a real difference in average trial outcomes — with the usual caveat that an average is not a prediction.
| Wegovy | Zepbound | |
|---|---|---|
| Active ingredient | Semaglutide | Tirzepatide |
| Licensed for | Chronic weight management; cardiovascular risk reduction in some populations | Chronic weight management; obstructive sleep apnoea in obesity |
| How it is taken | Once weekly, any day, with or without food | Once weekly, any day, with or without food |
| Half-life | ~160 hours (about 7 days) | ~5 days |
| Starting dose | 0.25 mg | 2.5 mg |
| Highest dose | 2.4 mg | 15 mg |
| Maintenance | 2.4 mg weekly. If that is not tolerated, a prescriber may hold at 1.7 mg. | 5 mg, 10 mg or 15 mg weekly. |
| Device | Single-dose pen, one per week | Single-dose pen or vial |
| In-use window | 28 days (US label) or up to 6 weeks (EU label) | 21 days (US label) |
| Late dose allowed | 5 days | 4 days |
Where they genuinely differ
These are different molecules, so this is a real comparison rather than a comparison of labels.
- Target. Wegovy contains semaglutide and Zepbound contains tirzepatide. Tirzepatide is the outlier in this class: it activates the receptor for a second gut hormone, GIP, alongside the GLP-1 receptor. Everything else acts on GLP-1 alone.
- Clearance. Wegovy has a half-life of ~160 hours (about 7 days); Zepbound, ~5 days. That single number sets the dosing interval, how long escalation takes, how forgiving a missed dose is, and how gradually the effect fades when you stop.
- Ladder. Wegovy climbs through 5 steps; Zepbound through 6. More rungs means smaller jumps and more places to pause.
Wegovy
Wegovy is semaglutide licensed for weight management. Same molecule as Ozempic®, different label, higher ceiling, and a different pen: each Wegovy pen holds a single dose and is discarded after use.
The full escalation takes about sixteen weeks, which is longer than most people expect and is the single most common source of early disappointment. The starting dose is not a treatment dose; it exists so your gut can adapt. Judging the medicine at week three is judging it before it has started.
Full Wegovy reference · dosing · side effects
Zepbound
Zepbound is tirzepatide licensed for weight management — the same molecule as Mounjaro®, under a different label. It also carries an approval for obstructive sleep apnoea in people with obesity, which is the first indication of its kind in this class.
Zepbound is a United States product. In Europe and much of the rest of the world, tirzepatide for weight management is prescribed as Mounjaro® instead — which is why guidance written for a US audience often names a product that does not exist in your pharmacy.
Full Zepbound reference · dosing · side effects
Side effects compared
The honest answer is that the gastrointestinal profile is broadly similar across this whole class, because it comes from the same mechanism: a stomach that empties more slowly. Nausea, early fullness, constipation and reflux appear on every label here.
What differs is intensity, and intensity tracks dose and effect size rather than the specific molecule. A product that produces a larger average metabolic change tends to produce more of the gut effects along with it. Comparing two products at the doses people actually take is therefore more informative than comparing them at their maximums — and both are less informative than your own first two dose increases.
Which is more effective?
Trials give averages, and averages are the right way to compare products and the wrong way to predict an individual. Where head-to-head data exist, they show real differences between molecules — but the spread of individual responses within either arm is wider than the gap between the arms.
What that means in practice: the product with the better trial number is a reasonable starting assumption and a poor guarantee. Plenty of people do better on the one the numbers favour less, and the only way to find out which group you are in is to take one properly — at a maintenance dose, for long enough, with the schedule kept.
Switching between them
Do not switch on your own. Doses are not interchangeable between molecules and there is no conversion factor. Moving across without re-escalating reproduces the worst of a first escalation, at full strength.
A supervised switch normally means starting the new product near the bottom of its own ladder even if you were at the top of the previous one, and accepting a few weeks of reduced effect while levels rebuild. Where the two products share a molecule, the switch is simpler — but it is still a prescribing decision, because the licence and the ceiling change with it.
Availability
Which of these you can actually obtain depends on where you live. Licences differ between regions, brand names differ for identical molecules, and supply has been intermittent across this whole class. A comparison that concludes one product is preferable is of limited use if your pharmacy cannot get it.
Common questions
How long does it take to get to the full Wegovy dose?
About sixteen weeks — five doses, four weeks each. This is longer than most people expect and is the most common source of early disappointment. The 0.25 mg starting dose is not a treatment dose; it exists so your gut can adapt.
Does Wegovy cause muscle loss?
Rapid weight loss takes lean tissue with it unless protein intake and resistance training make it not. This is the least discussed and most consequential part of the treatment. We cover the numbers here.
Is Zepbound dosed the same as Mounjaro?
Yes — identical molecule, identical ladder, identical increments. The difference between the two products is the licence and the market, not the schedule.
Does Zepbound help with sleep apnoea?
It carries an approval for obstructive sleep apnoea in people with obesity — the first indication of its kind in this class. Whether it is appropriate for you is a clinical judgement, not something a website can answer.
Cost, coverage and supply
Price is frequently the deciding factor and it is the one this site can say least about, because it varies by country, by health system, by insurer and by indication. Two things are worth knowing in general terms.
First, coverage usually follows the licence. A product licensed for diabetes is often funded for diabetes and not for weight management, even when the molecule is identical to one that is. That is why the same substance can be straightforward to obtain under one brand name and difficult under another.
Second, supply across this whole class has been intermittent, and shortages have moved between products rather than affecting all of them at once. A plan that depends on one specific brand being available every month is more fragile than it looks. It is worth asking your prescriber what the alternative would be if your product became unavailable — before it does.
Questions worth asking about this choice
- Which of these is licensed for my indication where I live?
- Which one can you actually obtain reliably at the moment?
- Is there a reason from my history to prefer one over the other?
- If this one does not suit me, what would we try next, and would I have to start the ladder again?
- What would we regard as this having worked, and by when?
That last question is the one people most often leave the room without having asked, and it is the one that prevents a treatment drifting for a year without anyone deciding whether it is working.
A note on sources. The figures in the table come from the manufacturers' approved labelling and from published pharmacokinetic data. Regional labels differ, sometimes materially — where a number matters, the leaflet in your own box outranks anything written here. Our editorial standards set out how these pages are sourced and corrected.
What the choice actually depends on
Not, mostly, on which of these two is better. It depends on your indication, your medical history, what is licensed and funded where you live, what your prescriber can obtain, and which routine you can realistically sustain for a year. A table cannot weigh those.
What a table can do is tell you what you are being offered and what questions to ask about it — which turns a consultation into a shorter and more useful conversation than it would otherwise be.