The short answer
Zepbound (tirzepatide) produces more average weight loss than Wegovy (semaglutide) in clinical trials — roughly 22% vs 15%. But Wegovy has more long-term safety data, better insurance coverage in some markets, and a new oral option. The right choice depends on your insurance, your tolerance for side effects, and how much weight you need to lose.
What are Wegovy and Zepbound?
Wegovy is an injectable semaglutide made by Novo Nordisk. It was the first GLP-1 receptor agonist approved specifically for chronic weight management (June 2021). In January 2026, the FDA also approved an oral version — the Wegovy pill.
Zepbound is an injectable tirzepatide made by Eli Lilly. It was approved for chronic weight management in November 2023. Tirzepatide is a dual GIP/GLP-1 receptor agonist, meaning it activates two hormone pathways instead of one.
Both are weekly injections prescribed alongside diet and exercise for adults with BMI ≥30, or BMI ≥27 with at least one weight-related condition.
Efficacy: How much weight will you lose?
This is where the data gets interesting. Head-to-head data between semaglutide and tirzepatide isn't from a single large obesity trial, but the cross-trial comparison is consistent:
Wegovy (STEP trials):
- STEP 1: 14.9% average weight loss at 68 weeks (vs 2.4% placebo)
- STEP 3 (with intensive lifestyle): 16% average weight loss
- STEP 5 (2-year data): ~15% maintained at 104 weeks
- About 1 in 3 patients lost ≥20%
Zepbound (SURMOUNT trials):
- SURMOUNT-1 (15 mg): 22.5% average weight loss at 72 weeks
(vs 2.4% placebo)
- SURMOUNT-2 (diabetes, 15 mg): 14.7% average weight loss
- About 1 in 3 patients lost ≥25%
In the SURPASS head-to-head diabetes trial (tirzepatide vs semaglutide 1 mg, not the obesity dose), tirzepatide showed greater weight loss at every dose level.
Bottom line on efficacy: Zepbound produces roughly 5–7 percentage points more weight loss than Wegovy on average. For a 250-pound person, that's the difference between losing ~37 pounds (Wegovy) and ~56 pounds (Zepbound). That's significant.
However, averages hide individual variation. Some patients respond dramatically to semaglutide and poorly to tirzepatide, and vice versa. If one medication isn't working after 4–6 months at maintenance dose, switching is a reasonable option.
Side effects: How do they compare?
Both drugs share the core GLP-1 side effect profile: nausea, vomiting, diarrhea, and constipation. These are typically worst during dose titration and improve over time.
Wegovy side effects (STEP 1):
- Nausea: 44% (vs 18% placebo)
- Diarrhea: 30% (vs 16% placebo)
- Vomiting: 24% (vs 6% placebo)
- Constipation: 24% (vs 11% placebo)
- Discontinuation due to side effects: 7%
Zepbound side effects (SURMOUNT-1, 15 mg):
- Nausea: 33% (vs 10% placebo)
- Diarrhea: 25% (vs 10% placebo)
- Vomiting: 13% (vs 3% placebo)
- Constipation: 11% (vs 5% placebo)
- Discontinuation due to side effects: 6.6%
Interpretation: Zepbound actually has slightly lower rates of GI side effects despite producing more weight loss. This is one of its underappreciated advantages. The GIP component may partially buffer the GI effects of the GLP-1 activation.
Both drugs carry the same boxed warning about thyroid C-cell tumors (observed in rodents, not confirmed in humans) and are contraindicated in patients with personal or family history of medullary thyroid carcinoma or MEN2.
Cost: What will you actually pay?
List prices (without insurance)
- Wegovy injection: ~$1,350/month (WAC)
- Wegovy pill: pricing not yet stabilized; early reports
suggest $800–$1,000/month
- Zepbound: ~$1,060/month (WAC)
With insurance
Coverage varies dramatically by insurer and plan:
- Wegovy has broader formulary coverage as of early 2026,
partly because it's been on the market longer. It also received an expanded FDA indication for cardiovascular risk reduction (SELECT trial), which has pushed more insurers to cover it.
- Zepbound is gaining coverage but is still excluded from
some plans that cover Wegovy. Lilly's LillyDirect program has helped narrow the gap.
Through telehealth (cash pay)
- Semaglutide (compounded): $149–$299/month
- Tirzepatide (compounded): $199–$399/month
- Brand Wegovy via telehealth: $349–$449/month
- Brand Zepbound via telehealth: $399–$499/month
[program:mochi-health]
Insurance and access
Wegovy advantages:
- SELECT trial CV indication gives prescribers a stronger case
for prior authorization
- Longer track record means more formulary listings
- Medicare coverage expanding in 2026 under recent legislation
(for cardiovascular indication)
- Oral formulation doesn't require cold-chain shipping
Zepbound advantages:
- Lilly's LillyDirect program offers brand-name medication at
competitive cash-pay prices
- Lilly has been more aggressive with savings cards
- Some plans that exclude semaglutide cover tirzepatide (and
vice versa) — always check both
Practical tip: if your insurer denies one, always try the other. About 15% of patients who are denied Wegovy get approved for Zepbound, and vice versa, simply because formulary decisions are often drug-specific rather than class-wide.
How do they work differently?
Wegovy (semaglutide) activates only the GLP-1 receptor. This slows gastric emptying, increases insulin secretion, reduces glucagon, and — most importantly for weight loss — acts on the hypothalamus to reduce appetite.
Zepbound (tirzepatide) activates both the GLP-1 and GIP receptors. GIP (glucose-dependent insulinotropic polypeptide) adds additional metabolic effects: enhanced fat oxidation, improved insulin sensitivity, and potentially some direct effects on adipose tissue.
The dual mechanism is likely why tirzepatide produces more weight loss — it's hitting two pathways instead of one. Whether this translates to better long-term outcomes (beyond just more pounds lost) is still being studied.
Dosing and administration
Wegovy injection
- Weekly subcutaneous injection (abdomen, thigh, or upper arm)
- Titration: 0.25 mg → 0.5 → 1.0 → 1.7 → 2.4 mg over ~17
weeks
- Pre-filled pen, no mixing required
- Must be refrigerated (or room temp for up to 28 days)
Wegovy pill
- Daily oral tablet (taken on empty stomach with ≤4 oz water)
- Must wait 30 minutes before eating or drinking anything else
- Titration schedule still being refined in clinical practice
Zepbound
- Weekly subcutaneous injection (same sites as Wegovy)
- Titration: 2.5 mg → 5 → 7.5 → 10 → 12.5 → 15 mg over ~20
weeks
- Pre-filled pen, no mixing required
- Must be refrigerated (or room temp for up to 21 days)
Who should choose Wegovy?
- You have insurance that covers Wegovy but not Zepbound
- You prefer a daily pill over weekly injections (Wegovy pill)
- You have a history of cardiovascular disease (SELECT trial
showed 20% reduction in major cardiovascular events)
- You've had good results on semaglutide in the past
- Your prescriber is more comfortable with semaglutide's longer
track record
Who should choose Zepbound?
- You need maximum weight loss and can tolerate the medication
- Your insurance covers Zepbound (or you're paying cash and
want more efficacy per dollar)
- You tried semaglutide and didn't respond well or had
intolerable side effects
- You have type 2 diabetes (tirzepatide's dual mechanism
provides stronger glucose control)
- You don't mind injections and want the most clinically
effective option currently available
Can you switch between them?
Yes. Switching between semaglutide and tirzepatide is common and straightforward. Your prescriber will typically restart the dose titration on the new medication, though some providers start at a mid-level dose if you were already tolerating a high dose of the previous drug.
Common reasons to switch:
- Insufficient weight loss after 4–6 months at maintenance dose
- Intolerable side effects that don't resolve
- Insurance coverage changes
- Cost considerations
There's no washout period needed between the two.
What about combining them?
Combining Wegovy and Zepbound (or any two GLP-1 agonists) is not recommended and is not supported by clinical evidence. The side effects would compound without clear additional benefit.
However, some prescribers are combining GLP-1 therapy with other agents — metformin, bupropion/naltrexone (Contrave), or phentermine — in certain patients. These combinations should only be managed by a prescriber experienced in obesity medicine.
Our bottom line
If you have access to both and your insurance doesn't favor one: Zepbound is the more effective drug for pure weight loss. The ~22% average weight loss at the highest dose is the best number in obesity pharmacotherapy right now.
If cardiovascular risk is your primary concern, Wegovy has the stronger evidence base (SELECT trial).
If needle aversion or cost is the deciding factor, the Wegovy pill offers a new option that didn't exist a year ago.
And if you've tried one and it's not working, switching to the other is always on the table. These are both excellent medications — the best choice is the one you can access, afford, and tolerate long enough to see results.