Semaglutide is a GLP-1 receptor agonist: it activates a single hormone receptor, GLP-1, to slow stomach emptying and curb appetite. In the only randomised trial that has ever compared semaglutide directly against tirzepatide, SURMOUNT-5, semaglutide produced less weight loss: 13.7% at 72 weeks against tirzepatide’s 20.2% (Aronne LJ, Horn DB, le Roux CW, Ho W, et al., New England Journal of Medicine, 3 July 2025, DOI 10.1056/NEJMoa2416394). That is the honest headline, not a footnote: semaglutide did not win that trial. What semaglutide brings instead is a longer FDA-approval and prescribing track record than tirzepatide, having reached the market first, and it is often easier to find through telehealth providers as a result.
Below: what the GLP-1 receptor actually does in the body, the head-to-head trial’s numbers with confidence intervals stated plainly rather than softened, what semaglutide is sold as and what it is approved for, what its side effects look like and when they show up, who has a genuine reason to start with semaglutide rather than tirzepatide, and how to actually get it prescribed today.
Key takeaways
What kind of drug is semaglutide?
Semaglutide is a GLP-1 receptor agonist, meaning it activates a single hormone receptor, GLP-1. It is sold as Ozempic for type 2 diabetes and Wegovy for weight loss, both FDA-approved.
Did semaglutide lose the head-to-head trial against tirzepatide?
Yes, on the primary weight-loss endpoint. SURMOUNT-5 measured semaglutide at 13.7% mean weight loss against tirzepatide’s 20.2% at 72 weeks (Aronne LJ, Horn DB, le Roux CW, Ho W, et al., NEJM, 2025). This page states that plainly rather than spinning it.
If tirzepatide beat it, why would anyone choose semaglutide?
Semaglutide has the longer FDA-approval and real-world prescribing track record of the two, having reached the market before tirzepatide, and it is often more widely available through telehealth providers as a result. That is a legitimate reason to start there, separate from the trial’s raw percentage gap.
What are semaglutide’s most common side effects?
Gastrointestinal, in both the semaglutide and tirzepatide arms of SURMOUNT-5: mostly mild to moderate, occurring primarily during dose escalation. No incidence figures broken out by specific symptom are published in the source this page draws from.
Is Ozempic the same drug as semaglutide?
Yes. Semaglutide is the active medication; Ozempic is its FDA-approved brand name for type 2 diabetes, and Wegovy is its FDA-approved brand name for weight loss.
Can you buy semaglutide without a prescription?
No. Semaglutide requires a licensed prescriber’s evaluation before it can be started. The providers this page links to prescribe compounded semaglutide after that evaluation, not without one.
What “GLP-1 receptor agonist” actually means
Semaglutide activates one hormone receptor: GLP-1. Stimulating that receptor slows stomach emptying, which keeps food in the stomach longer and extends the feeling of fullness after a meal, while also acting on appetite-signaling pathways in the brain that reduce hunger between meals. That single-receptor action is what curbs appetite, and it also plays a role in steadying blood sugar, which is why semaglutide is approved both for type 2 diabetes, as Ozempic, and for weight loss, as Wegovy, at different doses for each indication.
Semaglutide’s single-receptor mechanism is also the honest starting point for understanding why it produced less weight loss than tirzepatide in their one head-to-head trial. Tirzepatide activates that same GLP-1 receptor and adds a second one, GIP, which affects insulin response and appetite through a separate pathway. The extra receptor tirzepatide activates is the leading mechanistic explanation for the gap between the two drugs’ measured results, not a flaw in how semaglutide works on its own terms.
What the evidence shows: an honest read of the head-to-head trial
Semaglutide lost the head-to-head weight-loss comparison, and this page is not going to spin that result. SURMOUNT-5, published by Aronne LJ, Horn DB, le Roux CW, Ho W and colleagues in the New England Journal of Medicine on 3 July 2025 (DOI 10.1056/NEJMoa2416394, PMID 40353578, registered as ClinicalTrials.gov NCT05822830), was a phase 3b, open-label, controlled trial of 751 adults with obesity but without type 2 diabetes, randomised 1:1 to the maximum tolerated dose of semaglutide (1.7 or 2.4 mg) or tirzepatide (10 or 15 mg), both once weekly by subcutaneous injection, for 72 weeks.
Semaglutide’s mean body weight change at 72 weeks was −13.7% (95% CI −14.9 to −12.6), against tirzepatide’s −20.2% (95% CI −21.4 to −19.1), P<0.001. Waist circumference followed the same pattern: −13.0 cm (95% CI −14.3 to −11.7) on semaglutide against −18.4 cm (95% CI −19.6 to −17.2) on tirzepatide, also P<0.001. The trial also reports that tirzepatide participants were more likely than semaglutide participants to reach weight-loss reductions of at least 10%, 15%, 20% and 25% of body weight, stating that direction plainly without breaking out the exact share of participants at each threshold in the material this page draws from.
Two facts belong next to that result, and they cut both ways rather than rescuing semaglutide’s number. SURMOUNT-5 was open-label: every participant and investigator knew which drug a given person was taking, which can shape adherence and how borderline side effects get recorded, in either direction. And it was funded by Eli Lilly, the company that manufactures tirzepatide, not semaglutide’s manufacturer. Neither fact changes semaglutide’s measured 13.7% figure or turns it into a win. They are reasons to read the size of the gap carefully, not reasons to dismiss that a gap exists.
| Semaglutide | Tirzepatide | |
|---|---|---|
| Mechanism | GLP-1 receptor agonist | Dual GIP and GLP-1 receptor agonist |
| Brand names | Ozempic (type 2 diabetes), Wegovy (weight loss) | Mounjaro (type 2 diabetes), Zepbound (weight loss) |
| FDA approval status | FDA-approved | FDA-approved |
| Dosing in SURMOUNT-5 | Maximum tolerated 1.7 or 2.4 mg, once weekly, subcutaneous | Maximum tolerated 10 or 15 mg, once weekly, subcutaneous |
| SURMOUNT-5 result at 72 weeks | −13.7% mean body weight change (95% CI −14.9 to −12.6) | −20.2% mean body weight change (95% CI −21.4 to −19.1) |
Side effects
Semaglutide’s most common adverse events in SURMOUNT-5 were gastrointestinal, the same pattern reported in the tirzepatide group in the same trial. Most were mild to moderate and occurred primarily during dose escalation, the period when the dose is being stepped up toward the maximum tolerated level rather than held steady (Aronne LJ, Horn DB, le Roux CW, Ho W, et al., NEJM, 2025). That pattern matches semaglutide’s mechanism: the GLP-1 receptor it activates affects the digestive system directly, so a stronger version of that signal tends to be felt there first as the dose rises.
No incidence figures for specific side effects, broken down by symptom or by dose, are published in the material this page draws from, so none are stated here. Treat any specific side-effect percentage you see elsewhere attributed to SURMOUNT-5 with the same scrutiny this page applies to its own numbers, and check it against the source (DOI 10.1056/NEJMoa2416394).
Who semaglutide is for, and who it isn’t
Semaglutide has a genuine reason behind it that has nothing to do with winning SURMOUNT-5: it has the longer FDA-approval and prescribing track record of the two drugs, having reached the market before tirzepatide, and it is often easier to find through telehealth providers as a result. Anyone who weighs a longer real-world history and broader provider familiarity over the trial’s raw percentage gap has a legitimate reason to start with semaglutide. See the full comparison, including exactly how large that gap is and its caveats, on our semaglutide vs tirzepatide page.
Semaglutide is not the right choice for someone whose single priority is the maximum measured weight loss: SURMOUNT-5 found tirzepatide ahead on that specific endpoint, and this page is not going to argue otherwise. Whether that trade-off, a longer track record against a smaller measured result, matters more than the percentage gap is a personal judgment a licensed prescriber can help weigh against your own health history, not something either page can settle for you in the abstract.
How to actually get it
Semaglutide is FDA-approved and available today from a licensed prescriber after a medical evaluation. The providers below evaluate eligibility and prescribe compounded semaglutide, the same active ingredient sold under the brand names Ozempic and Wegovy. A compounded preparation carries the same active ingredient but is not itself an FDA-approved finished product, even when the compounding pharmacy is properly registered, which is worth knowing before you start.
These providers prescribe tirzepatide and semaglutide, which are FDA-approved. We may earn a commission, and it never changes your price.
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#1
TrimRxPersonalized programs, US pharmacies
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#2
Joi & BlokesHis & hers compounded GLP-1s
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#3
ReadyRxFast approvals on weight-loss meds
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The table below scores all five providers this site reviews against the same published rubric, including what each charges for semaglutide as the prescribed dose rises. Read our full TrimRx review for the most detailed look at one of them.
| # | Provider | Our score | Semaglutide | Tirzepatide | Worth knowing |
|---|---|---|---|---|---|
| 1 | TrimRx | 3.0/5 | from $199/mo | from $349/mo | Price stays flat as the dose escalates. |
| 2 | Joi & Blokes | 2.0/5 | $199/mo, billed quarterly | $299/mo, billed quarterly | First payment is $497 (semaglutide) or $747 (tirzepatide). |
| 3 | ReadyRx | 2.0/5 | $299/mo, or $249/mo prepaid | $399/mo | Refund if you have not lost 5% of baseline weight by 28 weeks. |
| 4 | AltRx | 0.5/5 | $89/mo promotional, $199/mo standard | $149/mo | BBB rates it F for failure to respond to 37 complaints. |
| 5 | Zevay | 0.0/5 | $149/mo | $187/mo | No BBB or Trustpilot profile found as of 16 July 2026. |
Scores are computed from our published rubric, shown in full on each review. Prices verified 16 July 2026: confirm your current price with the provider before you pay.
Sources
Aronne LJ, Horn DB, le Roux CW, Ho W, et al. “Tirzepatide as Compared with Semaglutide for the Treatment of Obesity.” New England Journal of Medicine, 3 July 2025. DOI: 10.1056/NEJMoa2416394. PMID 40353578. Registered as ClinicalTrials.gov NCT05822830. This is the primary source for every SURMOUNT-5 figure on this page.
How semaglutide works: frequently asked questions
How does semaglutide cause weight loss?
Semaglutide activates the GLP-1 hormone receptor, which slows stomach emptying and reduces appetite signaling in the brain. That single-receptor mechanism is why semaglutide is FDA-approved for weight loss as Wegovy and for type 2 diabetes as Ozempic.
Is semaglutide as effective as tirzepatide?
Not by SURMOUNT-5’s measured result: semaglutide produced 13.7% mean weight loss at 72 weeks against tirzepatide’s 20.2% (Aronne LJ, Horn DB, le Roux CW, Ho W, et al., NEJM, 2025). Semaglutide has a longer approval and prescribing track record than tirzepatide, which is a separate reason some people start with it regardless of that gap.
Is semaglutide FDA-approved for weight loss?
Yes. Semaglutide is FDA-approved for weight loss under the brand name Wegovy, and separately FDA-approved for type 2 diabetes under the brand name Ozempic. Both brand names contain the same active ingredient.
What is the difference between Ozempic and Wegovy?
Nothing in the active ingredient. Both are semaglutide. Ozempic is the FDA-approved brand name for type 2 diabetes; Wegovy is the FDA-approved brand name for weight loss. The drug itself does not change between the two.
How often is semaglutide injected?
Once weekly, by subcutaneous injection. That is the dosing schedule SURMOUNT-5 used for both its semaglutide arm (maximum tolerated 1.7 or 2.4 mg) and its tirzepatide arm (Aronne LJ, Horn DB, le Roux CW, Ho W, et al., NEJM, 2025).
Why did semaglutide lose the head-to-head trial?
The leading mechanistic explanation is tirzepatide’s second receptor: tirzepatide activates GIP alongside GLP-1, while semaglutide activates GLP-1 alone. SURMOUNT-5 was designed to measure the outcome, not to isolate exactly how much of the gap the extra receptor explains, so this is the best available explanation rather than a proven cause.
What about compounded semaglutide?
Compounded semaglutide contains the same active ingredient as Ozempic and Wegovy, but a compounded preparation is not itself an FDA-approved finished product, even when the compounding pharmacy is properly registered. SURMOUNT-5 tested the drug itself, not a compounded version, so its results describe the active ingredient rather than any specific compounded formulation.
Does semaglutide cause more side effects than tirzepatide?
SURMOUNT-5 reports gastrointestinal side effects as the most common in both the semaglutide and tirzepatide groups, mostly mild to moderate and occurring primarily during dose escalation, without publishing incidence figures broken out clearly enough in the available material to declare a clean winner between the two.