Wegovy® and Zepbound® are the two FDA-approved medications built specifically for chronic weight management — and for most people choosing between them, it's the single biggest decision in their treatment plan. Both are once-weekly injections. Both suppress appetite. Both have been studied in tens of thousands of patients, including head-to-head. But they're different molecules, made by different manufacturers, produce different amounts of weight loss, and are priced differently.
Here's what the clinical evidence actually shows, side by side.
Quick comparison
| Wegovy® | Zepbound® | |
|---|---|---|
| Active ingredient | Semaglutide | Tirzepatide |
| Manufacturer | Novo Nordisk | Eli Lilly |
| Mechanism | GLP-1 receptor agonist | Dual GLP-1 + GIP receptor agonist |
| FDA-approved indications | Chronic weight management, cardiovascular risk reduction, MASH | Chronic weight management, obstructive sleep apnea |
| FDA weight-loss approval | 2021 | 2023 |
| Average weight loss (pivotal trial) | 14.9% at 2.4 mg (STEP 1, 68 wks); 18.7% at 7.2 mg (STEP UP, 72 wks) | 20.9% at 15 mg (SURMOUNT-1, 72 wks) |
| Maximum dose | 7.2 mg weekly (Wegovy HD®); 2.4 mg for the original pen | 15 mg weekly |
| Titration | 5 steps over ~4 months | 6 steps over ~5 months |
| Typical side effects | GI-predominant: nausea, diarrhea, constipation, vomiting; boxed warning for thyroid C-cell tumors | Same GI profile, generally scaling with greater weight loss; same boxed warning |
| Storage before first use | Refrigerated 36–46°F; do not freeze. Room-temperature windows before first use are device-specific — see your device's guide | Refrigerated 36–46°F; do not freeze. Room-temperature windows before first use are device-specific — see your device's guide |
| Brand-name cost (no insurance) | ~$1,400/mo | ~$1,130/mo |
| Self-pay program | NovoCare (~$499/mo) | LillyDirect vials (~$349–$499/mo) |
Both are FDA-approved, cash-pay through Pallas; not billed to insurance.
How they work
Both medications mimic natural gut hormones released after eating — but Zepbound® mimics two of them, which is why it tends to be more effective.
Wegovy® (semaglutide) is a GLP-1 (glucagon-like peptide-1) receptor agonist. When you eat, your gut releases GLP-1, which signals fullness to your brain, slows stomach emptying, and prompts insulin release. Semaglutide mimics GLP-1 but lasts far longer than the natural hormone — a single weekly injection holds steady levels.
Zepbound® (tirzepatide) is a dual agonist. It activates the same GLP-1 receptor as semaglutide, plus a second receptor called GIP (glucose-dependent insulinotropic polypeptide), another gut hormone involved in fat metabolism and energy balance. Hitting both receptors produces stronger appetite suppression and greater average weight loss.
The one-sentence version
Wegovy® is a single-target appetite suppressor; Zepbound® is a dual-target version of the same idea — on average more effective, usually with a longer titration to maximum dose.
For a deeper look at the receptor biology behind both, read our explainer on how GLP-1 and GIP work.
Effectiveness: what the trials showed
Each drug has its own pivotal trial, and — unusually — they've also been compared directly.
STEP-1 (Wegovy®, semaglutide 2.4 mg weekly):
- Average weight loss: 14.9% of body weight at 68 weeks
- 50% of participants lost at least 15%
- 32% lost at least 20%
SURMOUNT-1 (Zepbound®, tirzepatide 15 mg weekly):
- Average weight loss: 20.9% of body weight at 72 weeks
- 57% of participants lost at least 20%
SURMOUNT-5 (head-to-head, 2025): In the first direct randomized comparison, participants on tirzepatide 10 mg or 15 mg weekly lost an average of 20.2% of body weight versus 13.7% on semaglutide 1.7 mg or 2.4 mg weekly at 72 weeks — a clear edge for Zepbound® in the same study. That trial capped semaglutide at 2.4 mg, though, and Wegovy®'s maximum dose is now 7.2 mg weekly; in the separate STEP UP trial that dose reached 18.7% at 72 weeks. Separate trials aren't a direct comparison, so read the head-to-head result as applying to the doses SURMOUNT-5 actually studied.
For a 220-lb starting weight, that's roughly 30 lbs on Wegovy® (1.7 mg or 2.4 mg) vs 44 lbs on Zepbound® (10 mg or 15 mg) at the SURMOUNT-5 averages. The weight loss projection calculator will model your specific starting point against either curve. Averages are not guarantees — individual response varies widely, and both are highly effective.
Dosing and titration
Both must start low and increase gradually to minimize side effects — mostly nausea. Titrating too fast is the most common reason people quit in the first month.
Wegovy® titration:
- Weeks 1–4: 0.25 mg
- Weeks 5–8: 0.5 mg
- Weeks 9–12: 1.0 mg
- Weeks 13–16: 1.7 mg
- Week 17+: 2.4 mg (maintenance)
Zepbound® titration:
- Weeks 1–4: 2.5 mg
- Weeks 5–8: 5 mg
- Weeks 9–12: 7.5 mg
- Weeks 13–16: 10 mg
- Weeks 17–20: 12.5 mg
- Week 21+: 15 mg (maintenance)
Many patients reach their goal at a lower dose and never need the maximum. Your provider adjusts titration based on how you tolerate each step.
Side effects compared
The profiles are very similar — both share the GLP-1 mechanism. The difference is mostly intensity, since greater weight loss tends to come with greater GI effects.
Most common (both, 20–40% of users in trials):
- Nausea (typically 1–4 weeks after each dose increase)
- Constipation
- Diarrhea
- Vomiting
- Abdominal discomfort
Less common but worth knowing:
- Fatigue (first few weeks)
- Loss of appetite to the point of under-eating (monitor protein)
- Injection-site reactions (minor redness)
- Gallbladder issues (~1–3% of users; risk rises with rapid weight loss)
Rare but serious:
- Pancreatitis
- Severe allergic reactions
- Boxed warning: because of a potential risk of thyroid C-cell tumors, both medications are contraindicated in people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 (based on animal studies; not conclusively linked in humans)
Most GI side effects resolve within 4–8 weeks of starting or after each titration step. For a deeper look, read our complete guide to GLP-1 side effects.
Cost comparison
Usually the deciding factor for anyone paying out of pocket.
Brand-name pricing (without insurance)
| Medication | Monthly cash price | Self-pay program |
|---|---|---|
| Wegovy® (semaglutide) | ~$1,400 | NovoCare self-pay ~$499/mo |
| Zepbound® (tirzepatide) | ~$1,130 | LillyDirect vials ~$349–$499/mo |
With insurance coverage these can drop to $25–150/month, but weight-loss coverage (non-diabetic indication) is inconsistent. Most commercial plans still don't cover weight-loss GLP-1s, and Medicare is prohibited by law from covering anti-obesity medications. Both manufacturers now run direct self-pay programs that meaningfully lower cash costs at lower doses.
Compounded alternatives
When a licensed clinician determines a brand-name product isn't clinically appropriate for a specific patient, compounded semaglutide and tirzepatide are available through US-licensed compounding pharmacies at lower cost. At Pallas, compounded semaglutide injection is $139 first month, then $199 every 4 weeks, charged once a clinician prescribes. Cancel anytime. Compounded tirzepatide injection is $179 first month, then $299 every 4 weeks, charged once a clinician prescribes. Cancel anytime. All cash-pay, with provider visits, dose adjustments, and shipping included.
Important context on compounded medications
Compounded medications are not FDA-approved products, are not generic versions of Wegovy® or Zepbound®, and have not been evaluated by the FDA for safety, efficacy, or quality. The STEP-1, SURMOUNT-1, and SURMOUNT-5 results above are for the FDA-approved brand products and have not been clinically established for compounded preparations. Compounded medications are prepared on a per-patient basis when a provider documents a specific clinical need. A Pallas provider will discuss current availability and clinical appropriateness during your intake.
Which one should you choose?
There's no universally right answer — but there are patterns.
Zepbound® tends to be the better fit if:
- You have a significant amount of weight to lose (40+ lbs)
- You want the highest average weight loss the evidence supports
- Semaglutide hasn't worked well for you in the past
- A slightly longer titration to maximum dose is fine
Wegovy® tends to be the better fit if:
- Your goal is more moderate (20–30 lbs)
- You want the medication with the longest post-market safety record (approved 2 years earlier)
- You're sensitive to medication effects and prefer fewer titration steps
- Your insurance happens to cover semaglutide but not tirzepatide (or vice versa)
Either works if:
- Your prescriber recommends one based on your health history
- Cost or your specific plan's formulary drives the decision
Ultimately a licensed clinician should make the call with you based on your medical history, goals, and tolerance.
Switching between Wegovy® and Zepbound®
Some patients start on one and move to the other — most often from Wegovy® to Zepbound® after a plateau or a preference for greater average weight loss, though the reverse also happens (cost, insurance formulary, or side-effect tolerance).
A few things to know before asking your provider about a switch:
- It's a clinical decision, not a straight substitution. The two medications aren't interchangeable at "equivalent" doses — there's no dose of Zepbound® that simply replaces a given dose of Wegovy®, since they act on different receptors. Your provider designs a new titration schedule based on your history and tolerance, typically starting Zepbound® at its lowest dose even if you were already at Wegovy®'s maximum.
- Expect your provider to specify timing between stopping one and starting the other, based on your prior dose and how you tolerated it.
- GI side effects can reset. Because Zepbound® activates an additional receptor (GIP) that Wegovy® doesn't, some patients notice a period of nausea or other GI effects similar to when they first started Wegovy®, even after being fully titrated on it.
- Check coverage and cost again. Insurance formularies and cash-pay pricing can differ between the two medications, so it's worth confirming before you switch.
If you're considering it, message your care team — a Pallas provider reviews your history and prescribes the transition plan; this isn't something to do on your own.
Bottom line: Zepbound® produces more weight loss on average — including head-to-head — while Wegovy® has a longer safety record and a shorter titration. Both are excellent FDA-approved options. The right choice depends on your goals, tolerance, insurance, and your clinician's judgment. It takes about 2 minutes to start the intake.
