Compare GLP-1 Medications: Semaglutide vs Tirzepatide
Choosing a GLP-1 medication depends on your health profile, your goals, and practical factors like form, availability, and cost. The two medications most people compare are semaglutide and tirzepatide. Both have large clinical trials behind them, and both are sold as brand-name products and, from some programs, as compounded formulations.
This guide breaks down the differences so you can have an informed conversation with a provider. For a broader overview of GLP-1 treatment, see our GLP-1 weight loss guide.
What’s in This Section
This section covers medication comparisons in depth. For more detail on specific topics, see:
- Semaglutide vs. Tirzepatide Head-to-Head – Direct clinical comparison, side effects compared, muscle loss data, and switching guidance
- GLP-1 vs. Other Weight Loss Options – How GLP-1 medications compare to bariatric surgery, phentermine, berberine, OTC supplements, and diet and exercise alone
- Weight Loss Results and Clinical Data – Real trial data on how much weight loss to expect, timelines, and before-and-after breakdowns
Medication Comparison at a Glance
| Semaglutide | Tirzepatide | Lower-dose (“microdose”) approaches | |
|---|---|---|---|
| Mechanism | GLP-1 receptor agonist | Dual GLP-1/GIP receptor agonist | Either medication below standard doses |
| Forms | Weekly injection or daily tablet | Weekly injection | Usually injection |
| Key trial | STEP 1: 14.9% average weight loss over 68 weeks | SURMOUNT-1: 16-22.5% weight loss over 72 weeks | No large trials of microdose regimens |
| Notable finding | 20% fewer major cardiovascular events (SELECT) | About 3x more fat loss than lean mass loss | Used for maintenance or to limit side effects |
| Typical eligibility | BMI 30+, or 27+ with a weight-related condition | BMI 30+, or 27+ with a weight-related condition | Varies by provider |
Eligibility shown reflects FDA labeling for the brand-name weight-management products; a licensed provider decides what is appropriate for you.
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Get StartedSemaglutide
Semaglutide is a GLP-1 receptor agonist originally developed for type 2 diabetes that has shown significant weight loss benefits in large-scale clinical trials. It works by mimicking the GLP-1 hormone your body naturally produces after eating.
How It Works
Semaglutide targets GLP-1 receptors in your brain and gut to:
- Reduce appetite by signaling your brain’s satiety center
- Slow gastric emptying so you feel full longer after meals
- Regulate blood sugar by enhancing insulin secretion
Clinical Evidence
The STEP 1 trial enrolled 1,961 participants and demonstrated that semaglutide achieved average weight loss of 14.9% of body weight over 68 weeks [1]. Participants also saw improvements in blood pressure, cholesterol, and blood sugar markers. The most common side effects were nausea and diarrhea, which typically improved as the body adjusted to the medication [1].
Importantly, the SELECT trial demonstrated that semaglutide reduced the risk of major cardiovascular events (heart attack, stroke, or cardiovascular death) by 20% in people with overweight or obesity [3]. This cardioprotective effect extends benefits beyond the scale.
Compounded formulations have not been independently evaluated by the FDA. The active ingredient semaglutide has been studied extensively in FDA-approved branded products, but compounded versions are prepared by licensed pharmacies and may differ in formulation, purity, and potency.
Who It May Suit
- People starting GLP-1 therapy who want a well-studied medication
- People who prefer a tablet, since semaglutide is available in oral form
- People for whom cardiovascular benefit is a priority, given the SELECT trial results
Tirzepatide
Tirzepatide is a dual-action medication that targets both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptors simultaneously. This two-pronged approach addresses appetite and metabolism from multiple hormonal pathways.
How It Works
By activating both GLP-1 and GIP receptors, Tirzepatide:
- Suppresses appetite through enhanced satiety signaling
- Improves insulin sensitivity via dual-receptor activation
- Increases energy expenditure through broader metabolic effects
Clinical Evidence
The SURMOUNT-1 trial enrolled 2,539 participants and demonstrated that tirzepatide produced weight loss ranging from 16% to 22.5% of body weight, depending on dose, over 72 weeks [2]. In a separate head-to-head comparison discussed in our semaglutide vs. tirzepatide guide, tirzepatide produced more average weight loss than semaglutide.
More importantly for body composition, tirzepatide produced approximately 3 times more fat loss than lean muscle loss [6]. This distinction matters because lean muscle is metabolically active and helps maintain energy expenditure long-term. The SURMOUNT trials showed this favorable body composition change across all age groups, including perimenopausal women.
Common side effects included nausea and diarrhea early in treatment, which typically improved over time [2]. Compounded formulations have not been independently evaluated by the FDA. The active ingredient tirzepatide has been studied extensively in FDA-approved branded products, but compounded versions are prepared by licensed pharmacies and may differ in formulation, purity, and potency.
Who It May Suit
- People interested in a dual-action approach that targets both GLP-1 and GIP receptors
- People who tried semaglutide and want to discuss a different mechanism with a provider
- People who prioritize preserving lean muscle while losing fat
Lower-Dose (“Microdose”) Approaches
Some providers prescribe semaglutide or tirzepatide below standard doses, most often for weight maintenance after reaching a goal, for people with a lower BMI, or to limit side effects. Some programs also add supplements such as NAD+, L-carnitine, or B12.
What to Know
- Microdose regimens have not been tested in large clinical trials the way standard doses have, so expected results are less certain
- Added supplements like NAD+ and B12 do not have strong evidence for weight management
- Stopping GLP-1 medication entirely is associated with weight regain in trials, which is one reason people ask about lower maintenance doses
Ask a provider what evidence supports any lower-dose plan, how dosing will be adjusted, and what the plan costs over time. Our microdosing guide covers this in more depth.
How to Decide: A Practical Guide
A licensed provider will recommend a medication based on your health evaluation, but here is a practical framework for thinking about your options:
By health goal
Significant weight to lose: Semaglutide or Tirzepatide. Your provider will recommend which is clinically appropriate based on your health profile and goals.
Interested in better fat loss vs. muscle loss: Tirzepatide's 3-to-1 fat-to-lean-mass ratio [6] makes it an option if preserving muscle during weight loss is a priority.
Want cardiovascular benefits: Semaglutide showed a 20% reduction in major cardiovascular events in the SELECT trial [3].
Maintaining current weight: Ask a provider about maintenance dosing. Lower-dose plans exist, but long-term evidence is still developing.
By budget
Prices vary widely by medication, dose, form (injection or tablet), and whether the product is brand-name or compounded. Many programs also raise the price as the dose increases.
When you compare, check what the monthly price includes: medication, provider visits, lab work, shipping, and any membership fee.
See our cost guide for details.
By preference
Prefer oral medication? Semaglutide is available as a daily tablet; tirzepatide is injectable.
Want evidence-backed efficacy? Both semaglutide [1] and tirzepatide [2] have extensive clinical trial data from large, independent studies.
Already lost weight? Ask about maintenance options, including whether a lower dose is appropriate for you.
Switching Between Medications
You’re not locked into one medication. People commonly:
Start at a low dose
Both medications start low and increase gradually over weeks to months, which helps limit side effects.
Reassess with a provider
Response, side effects, cost, and availability can all prompt a change. Switching usually means restarting the new medication at a lower dose rather than converting dose for dose.
Plan for maintenance
After reaching a goal, ask a provider about maintenance options, including dose adjustments, and what the evidence says about stopping.
Important Information About Compounded Medications
Compounded semaglutide and tirzepatide are prepared by licensed compounding pharmacies. The active ingredients are the same molecules found in brand-name GLP-1 medications, but compounded versions may differ in formulation, purity, and potency.
Compounded medications are not FDA-approved [7] and are not subject to the same review as mass-produced, branded drugs. FDA rules also limit when pharmacies may compound these drugs, so availability can change. A licensed provider determines the most appropriate treatment based on your individual health profile. For more, see our guide to compounded GLP-1 medications.
Citations
[1] Wilding JPH, et al. “Once-Weekly Semaglutide in Adults with Overweight or Obesity.” New England Journal of Medicine. 2021;384(11):989-1002. https://pubmed.ncbi.nlm.nih.gov/33567185/ (STEP 1 trial: 14.9% average weight loss over 68 weeks, 1,961 participants, nausea and diarrhea as most common side effects)
[2] Jastreboff AM, et al. “Tirzepatide Once Weekly for the Treatment of Obesity.” New England Journal of Medicine. 2022;387(3):205-216. https://pubmed.ncbi.nlm.nih.gov/35658024/ (SURMOUNT-1 trial: 16-22.5% weight loss over 72 weeks, 2,539 participants, 3 times more fat loss than lean mass loss)
[3] Lincoff AM, et al. “Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes.” New England Journal of Medicine. 2023. https://pubmed.ncbi.nlm.nih.gov/37952131/ (SELECT trial: 20% reduction in major adverse cardiovascular events)
[4] National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). “Prescription Medications to Treat Overweight and Obesity.” https://www.niddk.nih.gov/health-information/weight-management/prescription-medications-treat-overweight-obesity
[5] U.S. Food and Drug Administration. “Prescribing Information for tirzepatide for chronic weight management.” November 2023. https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/217806s000lbl.pdf
[6] Neeland IJ, et al. “Changes in lean body mass with GLP-1-based therapies.” Diabetes, Obesity and Metabolism. 2024. https://dom-pubs.onlinelibrary.wiley.com/doi/10.1111/dom.15728 (Evidence of preferential fat loss over lean mass with tirzepatide)
[7] U.S. Food and Drug Administration. “Compounding and the FDA: Questions and Answers.” https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers