Medication Guides

Semaglutide vs. Tirzepatide for Weight Loss: How They Compare in 2026

Both are highly effective GLP-1-based weight-loss medications, but they are not the same drug. Here is how they differ in mechanism, trial results, side effects, dosing, and cost — and how to think about which one fits you.

Reviewed by {{Medical Reviewer Name, Credential}} · Updated June 29, 2026 · 9 min read

The short answer: Semaglutide and tirzepatide both produce substantial weight loss by curbing appetite, but they work through different receptors. In clinical trials, tirzepatide produced more weight loss on average — up to ~24.3% of body weight in SURMOUNT-1, versus ~15% for semaglutide in STEP 1. Semaglutide is usually cheaper and has a longer track record. The right choice depends on your goals, tolerance for side effects, budget, and a licensed provider's assessment.

This is information, not medical advice. Consult a licensed provider before starting any treatment. The medications discussed include both FDA-approved brand-name drugs and compounded versions; compounded semaglutide and tirzepatide are not FDA-approved (see the full notice below).

How each one works

Semaglutide is a GLP-1 receptor agonist. It mimics glucagon-like peptide-1, a gut hormone that signals fullness to the brain, slows how fast the stomach empties, and helps regulate blood sugar. It is the active ingredient in the brand-name drugs Ozempic® and Wegovy® (Novo Nordisk).

Tirzepatide is a dual agonist: it activates the GLP-1 receptor and the GIP (glucose-dependent insulinotropic polypeptide) receptor. The added GIP activity is believed to enhance the appetite-suppressing and metabolic effects, which may explain its higher average weight loss in trials. It is the active ingredient in Mounjaro® and Zepbound® (Eli Lilly).

What the clinical trials showed

The clearest evidence comes from each drug's pivotal trial. In STEP 1 (NEJM, 2021), adults with obesity taking semaglutide 2.4 mg weekly lost an average of ~14.9% of body weight over 68 weeks, alongside diet and exercise. In SURMOUNT-1 (NEJM, 2022), tirzepatide produced average reductions that climbed with dose, reaching up to ~24.3% at the highest dose over 72 weeks.

~15%
Average weight loss
Semaglutide (STEP 1, 68 wks)
~24.3%
Up to, at highest dose
Tirzepatide (SURMOUNT-1, 72 wks)

Figures are clinical-trial averages combining medication with diet and exercise. Trials enrolled different populations and are not a head-to-head comparison. Individual results vary and are not guaranteed.

A direct comparison came later. In SURMOUNT-5, a head-to-head trial reported in 2025, tirzepatide produced significantly greater weight loss than semaglutide in adults with obesity — the first large randomized trial to compare the two directly. Even so, the difference is an average: many people do very well on semaglutide, and tolerability matters as much as the headline number.

Side effects and safety

The two drugs share a similar safety profile. The most common side effects are gastrointestinal — nausea, diarrhea, vomiting, and constipation — and they are usually most noticeable when the dose is being increased. Starting low and titrating slowly is the standard approach to limit them.

Both carry a boxed warning regarding the risk of thyroid C-cell tumors, based on rodent studies; they are not recommended for people with a personal or family history of medullary thyroid carcinoma or MEN 2. Rarer but serious risks include pancreatitis and gallbladder problems. A licensed provider should review your full medical history before prescribing either medication.

Dosing and administration

Both are once-weekly subcutaneous injections, self-administered with a small needle into the abdomen, thigh, or upper arm. Both start at a low dose that is increased gradually over weeks to the target dose, which improves tolerability. An oral form of semaglutide also exists; tirzepatide is currently injection-only.

Cost: what to expect

Cost varies widely by format. Brand-name Wegovy and Zepbound carry manufacturer list prices that are often over $1,000/month before insurance or savings programs. Compounded versions — prepared by licensed compounding pharmacies — are typically far less expensive, and semaglutide generally costs less than tirzepatide at a comparable program.

As a current reference point, one telehealth provider in our reviews, MaxLife, lists compounded semaglutide from $175/month and compounded tirzepatide from $195/month, with the per-month cost falling on longer plans. Prices across the market change frequently — always confirm current pricing and exactly what is included (consultation, shipping, dose changes) before enrolling.

About compounded medication: Compounded semaglutide and tirzepatide are not FDA-approved and have not been reviewed by the FDA for safety, effectiveness, or quality. They are prepared by U.S.-licensed compounding pharmacies when a licensed provider determines treatment is appropriate. Compounded semaglutide is not Ozempic® or Wegovy®; compounded tirzepatide is not Mounjaro® or Zepbound®.

How to choose between them

Reasonable factors to weigh with your provider:

  • Weight-loss goal. If maximizing average weight loss is the priority and you tolerate it, the trial data favor tirzepatide. For solid, well-established results at lower cost, semaglutide is a strong option.
  • Side-effect tolerance. Both can cause GI effects; some people tolerate one better than the other. Slow titration helps with either.
  • Budget. Semaglutide is generally the lower-cost choice, especially in compounded form.
  • Track record. Semaglutide has been in wide weight-management use longer.
  • Medical history. Certain conditions make either drug inappropriate — this is the provider's call.

The bottom line

Both semaglutide and tirzepatide are effective, evidence-backed medications for weight management when combined with diet and lifestyle changes. Tirzepatide shows higher average weight loss in trials; semaglutide is typically cheaper with a longer history. There is no universally "better" drug — only the one that best fits your goals, tolerance, budget, and medical history, prescribed and monitored by a licensed provider.

Frequently asked questions

Is tirzepatide more effective than semaglutide?

In separate pivotal trials, tirzepatide produced higher average weight loss (up to ~24.3% in SURMOUNT-1) than semaglutide (~15% in STEP 1), and the 2025 head-to-head SURMOUNT-5 trial also favored tirzepatide. But these are averages across different populations; individual results vary and semaglutide works very well for many people.

Can I switch from one to the other?

Switching is sometimes done — for tolerability, cost, or results — but it should be managed by a licensed provider, who will set an appropriate starting dose on the new medication rather than matching the old one directly.

Are the compounded versions the same as the brand-name drugs?

No. Compounded semaglutide and tirzepatide use the same active ingredient but are prepared by compounding pharmacies and are not FDA-approved. Compounded semaglutide is not Ozempic® or Wegovy®; compounded tirzepatide is not Mounjaro® or Zepbound®.

How long do I need to take it?

GLP-1 medications are generally used long-term for weight management; studies show weight tends to return after stopping. The right duration is an individual decision made with your provider.

References

  1. Wilding JPH, et al. "Once-Weekly Semaglutide in Adults with Overweight or Obesity" (STEP 1). New England Journal of Medicine, 2021. nejm.org
  2. Jastreboff AM, et al. "Tirzepatide Once Weekly for the Treatment of Obesity" (SURMOUNT-1). New England Journal of Medicine, 2022. nejm.org
  3. U.S. Food & Drug Administration — prescribing information for Wegovy®, Ozempic®, Zepbound®, Mounjaro®. fda.gov