The two medications reshaping weight loss
If you're researching GLP-1 medications for weight loss, you've almost certainly encountered two names: semaglutide (the active ingredient in Wegovy and Ozempic) and tirzepatide (the active ingredient in Zepbound and Mounjaro). Both are injectable medications that work on your body's appetite-regulation systems, but they do so in meaningfully different ways—and the differences matter for your results, your side effects, and your wallet.
This isn't a vague "both are great, talk to your doctor" comparison. We've reviewed the clinical trial data, tracked real-world pricing, and talked to people on both medications. Here's what we found.
How they work: one receptor vs. two
Semaglutide is a GLP-1 receptor agonist. It mimics the natural GLP-1 hormone your gut produces after eating, telling your brain you're full and slowing stomach emptying. This single-mechanism approach has been studied extensively since semaglutide's initial approval for diabetes in 2017.
Tirzepatide is a dual GIP/GLP-1 receptor agonist—it activates two hormonal pathways instead of one. GIP (glucose-dependent insulinotropic polypeptide) adds a second layer of metabolic regulation, enhancing insulin sensitivity and potentially boosting fat metabolism beyond what GLP-1 alone achieves. Think of semaglutide as pulling one lever; tirzepatide pulls two.
Weight loss: what the trials actually show
This is where the data gets concrete.
| Metric | Semaglutide 2.4mg | Tirzepatide 15mg |
|---|---|---|
| Avg. weight loss | 14.9% | 20.9% |
| Trial duration | 68 weeks | 72 weeks |
| Participants losing ≥20% | ~32% | ~40% |
| Key trial | STEP 1 | SURMOUNT-1 |
| FDA weight loss approval | June 2021 (Wegovy) | Nov 2023 (Zepbound) |
Tirzepatide's ~6 percentage point advantage in average weight loss is clinically significant. For a 220-pound person, that's roughly 13 additional pounds lost. However, individual variation is substantial—some people respond dramatically to semaglutide and modestly to tirzepatide, and vice versa. The trial averages tell one story; your biology may tell another.
Side effects: similar profiles, different intensities
Both medications share the core GLP-1 side effect profile: nausea, diarrhea, constipation, and vomiting, especially during dose titration. In clinical trials, roughly 40–50% of participants on either medication reported at least one GI side effect. Most resolved within the first few weeks as the body adjusted.
Where they differ is in the titration experience. Tirzepatide's dose escalation schedule is more gradual (starting at 2.5mg, stepping through 5mg, 7.5mg, 10mg, 12.5mg, and up to 15mg), which may smooth out side effects. Semaglutide escalates through 0.25mg, 0.5mg, 1mg, 1.7mg, and 2.4mg. Both medications carry boxed warnings about thyroid C-cell tumors based on animal studies, and both are contraindicated in patients with a personal or family history of medullary thyroid carcinoma or MEN type 2.
Pricing in 2026: the real math
Brand-name pricing has converged somewhat in 2026, but there are still meaningful differences.
| Option | Semaglutide | Tirzepatide |
|---|---|---|
| Brand list price | ~$1,349/mo (Wegovy) | ~$1,059/mo (Zepbound) |
| Manufacturer cash-pay | $349/mo (NovoCare) | $349–$699 (LillyDirect) |
| With savings card | As low as $25/mo | As low as $25/mo |
| Compounded | $149–$299/mo | $199–$399/mo |
For cash-pay patients, compounded semaglutide is generally the cheapest entry point at $149–$299 per month. Compounded tirzepatide tends to run slightly higher. If you have commercial insurance that covers GLP-1 medications, both can drop to as low as $25 per month with manufacturer savings cards—but getting insurance approval often requires prior authorization and may take weeks.
Cardiovascular and beyond-weight benefits
Semaglutide has a significant edge in non-weight-loss evidence. The SELECT trial (2023) demonstrated a 20% reduction in major adverse cardiovascular events in patients with established cardiovascular disease, earning Wegovy an expanded FDA indication for cardiovascular risk reduction. Additional indications now include obstructive sleep apnea.
Tirzepatide's cardiovascular outcomes trial (SURPASS-CVOT) is ongoing, and early metabolic data is promising—tirzepatide shows stronger improvements in HbA1c and insulin sensitivity. But until the cardiovascular trial results publish, semaglutide's heart-health evidence is unmatched.
New in 2026: oral options emerge
Both medications now have oral formulations in the market. The Wegovy pill (oral semaglutide for weight loss) received FDA approval and is available at $149 per month for starter doses. Foundayo (orforglipron), an oral non-peptide GLP-1 agonist from Eli Lilly, launched in April 2026 at $149 per month. These oral options eliminate the injection barrier for patients who are needle-averse, though the injectable versions generally show stronger weight loss in clinical data.
Our verdict
If raw weight loss numbers are your primary goal and you're paying cash, tirzepatide is the stronger performer in clinical data. The dual-agonist mechanism translates to roughly 6 additional percentage points of body weight loss on average, and the longer dose escalation may be easier to tolerate.
If you want the longest track record, the most insurance pathways, and proven cardiovascular benefits, semaglutide is the more established choice. It also has more flexible formulations, including the new oral pill.
For compounded options—where most cash-pay patients land—semaglutide is generally more affordable. Compounded tirzepatide costs more but delivers proportionally more weight loss. Your provider should help you weigh these tradeoffs against your health history and goals.