Semaglutide and tirzepatide are the two most studied GLP-1-class compounds for weight management, available both as FDA-approved prescription medications and as labeled research compounds. Here’s how they compare, and where each is actually available.
Mechanism
Semaglutide is a GLP-1 receptor agonist — it acts on a single hormone pathway to slow digestion and increase feelings of fullness. Tirzepatide activates both the GIP and GLP-1 receptors, a dual mechanism thought to be why it has shown somewhat greater average weight loss in head-to-head trial data. See our full guide to how tirzepatide injections work for more detail.
Weight loss in trial data
In published head-to-head comparative data, tirzepatide has shown greater average weight loss than semaglutide at equivalent trial endpoints. Trial averages describe group results, not a guaranteed outcome for any individual, and your own response depends on your health history and how your prescriber titrates your dose.
Available as prescription medication
Neither semaglutide nor tirzepatide is sold under its chemical name as a prescription product — each is available under specific FDA-approved brand names, licensed for different indications:
| Active ingredient | Diabetes-indicated brand | Weight-management-indicated brand |
|---|---|---|
| Semaglutide | Ozempic | Wegovy |
| Tirzepatide | Mounjaro | Zepbound |
See our Ozempic vs Mounjaro and Wegovy vs Zepbound comparisons for how the specific brand-name products differ.
Dosing
Both are titrated gradually from a low starting dose to reduce side effects like nausea. See our full tirzepatide dosing schedule for a worked example of how titration typically progresses. Never start, stop, or change your dose without direction from your prescriber.
Side effects
Both share a similar gastrointestinal side-effect profile — nausea, diarrhoea, and constipation are the most commonly reported, usually easing as your body adjusts to each dose increase. See our Ozempic side effects guide and Mounjaro side effects guide for details.
Available for laboratory research
Separately from the prescription medications above, both compounds are also available as labeled research peptides — Semaglutide and Tirzepatide — supplied strictly for in-vitro laboratory research use, not as a substitute for the prescription medications described above. See our guide to choosing quality research peptides for more on how these differ from clinical-grade medication.
Eligibility and how to order
Prescription semaglutide and tirzepatide products are prescription-only. Place your order, and a licensed physician will speak with you directly on a live call to review your health history and confirm a prescription is medically appropriate before anything ships — see our full eligibility guide to check whether you’re likely to qualify first.
Which one is right for you?
If you have type 2 diabetes and haven’t tried a GLP-1 medication before, your prescriber may start with semaglutide (Ozempic). If you’re specifically focused on weight management, or haven’t seen the results you wanted from a single-pathway GLP-1 medication, tirzepatide’s dual mechanism may be discussed instead. This is a decision your prescriber will help you make based on your health history and goals.
Frequently Asked Questions
Is tirzepatide more effective than semaglutide?
Tirzepatide has shown somewhat greater average weight loss in head-to-head trial data, likely due to its dual GIP/GLP-1 mechanism, but individual response varies and your prescriber will advise based on your history.
What’s the difference between semaglutide and Ozempic or Wegovy?
Semaglutide is the active ingredient; Ozempic and Wegovy are FDA-approved brand-name products containing it, licensed for different indications (diabetes management and chronic weight management, respectively).
Can I buy semaglutide or tirzepatide without a prescription?
The FDA-approved prescription medications require a prescription issued after a licensed physician’s review. Separately, both compounds are also available as labeled research peptides for laboratory use only, not as a substitute for prescription medication.
Do semaglutide and tirzepatide have the same side effects?
Both share a similar gastrointestinal side-effect profile, though individual tolerability can differ between the two.
Ready to find out which one fits your health profile? Start your free eligibility assessment and our clinical team will guide you.
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