Zepbound vs Wegovy: What's Actually Different

Two medications dominate prescription weight loss, and everyone starting this journey eventually asks the same question: which one is better? Here’s what the evidence actually says — and where “better” depends on you.

The short version

• Zepbound (tirzepatide, Eli Lilly) activates two gut-hormone receptors: GIP and GLP-1.
• Wegovy (semaglutide, Novo Nordisk) activates one: GLP-1.
• Both are weekly injections, FDA-approved for chronic weight management alongside diet and activity. The same molecules appear under different names for type 2 diabetes (Mounjaro and Ozempic, respectively).

Results: the one head-to-head we have

For years the comparison relied on separate trials. The head-to-head SURMOUNT-5 trial settled the average question: tirzepatide produced roughly 20% average body-weight loss versus about 14% for semaglutide over 72 weeks (Aronne et al., NEJM 2025).

Three honest footnotes before you conclude “Zepbound wins”:

1. Averages hide spread. In every trial, some participants lose far more than the mean and some far less — on both drugs. Your response is not predictable in advance.
2. The “loser” is still remarkable. Fourteen percent average loss was unimaginable in a medication five years ago.
3. The best drug is the one you can actually get and stay on — coverage, supply, tolerability, and price decide outcomes as often as pharmacology does.

Side effects: more alike than different

Both share the classic GLP-1 gastrointestinal profile — nausea, constipation, diarrhea, mostly early and around dose increases — at broadly similar rates in trials. Serious risks (pancreatitis, gallbladder disease, the thyroid-tumor boxed warning based on rodent data) apply to both classes and are exactly the conversation to have with your prescriber, not a comparison point to shop on. Our side-effect survival guide applies equally to either.

Dosing and practicalities

Both are weekly pens, titrated stepwise over months. Zepbound tops out at 15 mg weekly, Wegovy at 2.4 mg — the numbers aren’t comparable across drugs and don’t matter to you; what matters is that both need patient, gradual escalation, and both have had periodic supply constraints at specific doses.

Cost: usually the real decider

Coverage varies by plan and diagnosis far more than by molecule. Both list above $1,000/month without insurance; both manufacturers run savings programs and direct-to-consumer options substantially below list. In practice, most people end up on whichever drug their insurance actually covers — walk the full decision path in our real-cost map.

How to actually decide

Bring three questions to your prescriber: Which does my insurance cover for my diagnosis? Is there a clinical reason to prefer one for my history? If the first choice plateaus or isn’t tolerated, what’s the switching plan? That conversation beats any internet comparison — including this one.