Weight Loss

Semaglutide vs Tirzepatide: Which GLP-1 Is Right for You?

Semaglutide and tirzepatide are the two most effective injectable medications available for weight loss today. Both belong to the incretin-based drug class and work by mimicking gut hormones that regulate appetite and blood sugar, but they differ in a fundamental way: semaglutide targets a single receptor (GLP-1) while tirzepatide is a dual agonist that activates both GLP-1 and GIP receptors simultaneously.

Semaglutide is the active ingredient in Ozempic (for type 2 diabetes) and Wegovy (for weight management). In the STEP 1 trial of FDA-approved Wegovy, semaglutide demonstrated greater than 15% average body weight reduction, and it has the longest real-world track record among modern weight loss injectables. Tirzepatide, the active ingredient in Mounjaro and Zepbound, arrived later but produced even larger weight loss numbers -- in the SURMOUNT-1 trial of FDA-approved Zepbound, tirzepatide demonstrated 20-22.5% total body weight reduction at 72 weeks.

For patients considering a GLP-1 medication, the choice often comes down to cost, availability, side effect tolerance, and how much weight needs to be lost. Both require a prescription and ongoing medical supervision. Here is how they compare across every factor that matters.

Semaglutide

From $197/mo

Semaglutide is a GLP-1 receptor agonist that mimics the incretin hormone GLP-1. It slows gastric emptying, reduces appetite signals in the brain, and helps regulate blood sugar levels. Administered as a once-weekly subcutaneous injection.

Best for

Patients looking for an affordable, well-established GLP-1 with a strong safety record. Good first-line option for those with moderate weight loss goals or those who want the most clinical data behind their medication.

Advantages

  • 15-17% average body weight loss demonstrated in clinical trials of FDA-approved Wegovy (STEP 1)
  • Longest real-world safety and efficacy track record
  • More affordable starting price than tirzepatide
  • Available as oral melt formulation for needle-averse patients
  • Extensive insurance and compounding availability

Considerations

  • Single-receptor mechanism produces less weight loss than tirzepatide
  • GI side effects (nausea, vomiting) common during dose escalation
  • Requires gradual dose titration over several months
  • Weight regain common if discontinued without lifestyle changes
View Semaglutide Details

*Compounded medication. Not FDA-approved.

Tirzepatide

From $258/mo

Tirzepatide is a first-in-class dual GIP/GLP-1 receptor agonist. By activating both incretin receptors simultaneously, it produces more potent appetite suppression and greater metabolic effects than single-pathway GLP-1 drugs. Administered as a once-weekly subcutaneous injection.

Best for

Patients with significant weight to lose (BMI 35+) or those who have not achieved target results with semaglutide alone. Also suited for patients with type 2 diabetes, as tirzepatide has shown superior A1C reduction.

Advantages

  • 20-22.5% average body weight reduction in clinical trials of FDA-approved Zepbound (SURMOUNT-1)
  • Dual mechanism targets both GLP-1 and GIP pathways
  • Often better GI tolerability than semaglutide at equivalent efficacy
  • Superior blood sugar and A1C improvements
  • Continued weight loss demonstrated through 72+ weeks

Considerations

  • Higher monthly cost than semaglutide
  • Less long-term real-world data (newer medication)
  • Nausea and GI side effects still common during titration
  • Less insurance coverage currently available
View Tirzepatide Details

*Compounded medication. Not FDA-approved.

Head-to-Head Comparison

Drug class

Semaglutide

GLP-1 receptor agonist

Tirzepatide

Dual GIP/GLP-1 receptor agonist

Brand names

Semaglutide

Ozempic, Wegovy

Tirzepatide

Mounjaro, Zepbound

FDA approved for weight loss

Semaglutide

Yes (Wegovy, 2021)

Tirzepatide

Yes (Zepbound, 2023)

How taken

Semaglutide

Once-weekly subcutaneous injection

Tirzepatide

Once-weekly subcutaneous injection

Dose range

Semaglutide

0.25 mg to 2.4 mg

Tirzepatide

2.5 mg to 15 mg

Avg weight loss (clinical trials)

Semaglutide

~15-17% body weight at 68 weeks (STEP 1 trial, FDA-approved Wegovy)

Tirzepatide

~20-22.5% body weight at 72 weeks (SURMOUNT-1 trial, FDA-approved Zepbound)

Onset of appetite changes

Semaglutide

1-2 weeks

Tirzepatide

1-2 weeks

Common side effects

Semaglutide

Nausea, diarrhea, constipation, vomiting

Tirzepatide

Nausea, diarrhea, constipation, decreased appetite

GI discontinuation rate

Semaglutide

~4.5% in trials

Tirzepatide

~4.3-7.1% depending on dose

Also treats type 2 diabetes

Semaglutide

Yes (as Ozempic)

Tirzepatide

Yes (as Mounjaro)

Starting price at INA

Semaglutide

$197/mo (6-month plan)

Tirzepatide

$258/mo (6-month plan)

Best for

Semaglutide

Budget-conscious, moderate weight loss goals

Tirzepatide

Maximum weight loss, prior semaglutide plateau

Which Should You Choose?

Both semaglutide and tirzepatide are well-studied GLP-1 receptor agonists. The FDA-approved branded versions (Wegovy and Zepbound) demonstrated significant weight loss in clinical trials. INA prescribes compounded formulations of these medications, which are not FDA-approved and have not undergone equivalent testing.

If you are starting your weight loss journey and want the most affordable, well-studied option, semaglutide is an excellent first choice. It has the longest track record and the FDA-approved version (Wegovy) demonstrated average weight loss of 15-17% in the STEP 1 trial. If you have a higher BMI, have not reached your target weight on semaglutide, or want the most aggressive results available, tirzepatide's dual-receptor mechanism showed measurably more weight loss in clinical data for the FDA-approved version (Zepbound). Your provider can help determine which medication aligns best with your health profile, budget, and goals.

Clinical trial data referenced on this page is from studies of FDA-approved branded medications (Wegovy/Ozempic for semaglutide, Zepbound/Mounjaro for tirzepatide) conducted in controlled settings. INA prescribes compounded formulations, which are not FDA-approved and have not undergone equivalent clinical testing. Results with compounded medications may differ. Compounded medications are custom-prepared by licensed pharmacies based on a provider’s prescription. INA is not affiliated with Novo Nordisk or Eli Lilly.

Frequently Asked Questions

Is tirzepatide better than semaglutide for weight loss?
In clinical trials of the FDA-approved branded versions, tirzepatide (Zepbound, SURMOUNT-1) produced greater average weight loss (20-22.5%) compared to semaglutide (Wegovy, STEP 1, 15-17%) at similar timeframes. However, 'better' depends on individual factors. Semaglutide is more affordable, has a longer track record, and produces excellent results for many patients. Tirzepatide may be worth the higher cost for patients who need maximum weight loss or have plateaued on semaglutide. INA prescribes compounded formulations, which have not undergone equivalent clinical testing.
Can I switch from semaglutide to tirzepatide?
Yes. Many patients who plateau on semaglutide transition to tirzepatide under medical supervision. Your provider will typically restart at the lowest tirzepatide dose and titrate upward, regardless of your previous semaglutide dose. There is usually no washout period required between the two medications.
Which has fewer side effects -- semaglutide or tirzepatide?
Both medications share similar GI side effects (nausea, vomiting, diarrhea, constipation), particularly during dose escalation. Some clinical data suggests tirzepatide may be slightly better tolerated at doses that produce equivalent weight loss, but individual responses vary significantly. Starting at the lowest dose and titrating slowly minimizes side effects with either medication.
Do I need to take semaglutide or tirzepatide forever?
Current evidence shows that weight regain is common after discontinuing either medication if lifestyle changes have not been established. Most providers recommend ongoing treatment or a carefully supervised tapering plan. Some patients successfully transition to a lower maintenance dose rather than stopping entirely.
How do compounded medications compare to branded versions?
Compounded semaglutide and tirzepatide are custom-prepared by licensed 503B pharmacies based on your provider's prescription. Compounded medications are not FDA-approved and have not undergone the same clinical testing as branded products like Wegovy or Zepbound. While they contain the same active pharmaceutical ingredient, the FDA does not review compounded medications for safety, effectiveness, or quality. Your provider will determine the most appropriate treatment option for your individual needs.
How much weight can I realistically expect to lose?
Results vary by individual. In clinical trials, the average semaglutide patient lost 15-17% of body weight, and the average tirzepatide patient lost 20-22.5%, both over approximately 68-72 weeks. Combined with diet and exercise, some tirzepatide patients achieved up to 26.6% weight loss. Your actual results will depend on starting weight, adherence, lifestyle changes, and individual metabolic factors. These figures are from clinical trials of FDA-approved branded medications and may not reflect outcomes with compounded formulations, which have not undergone equivalent testing.

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Warning: Compounded GLP-1s (Tirzepatide & Semaglutide)

Please contact your doctor ASAP and seek in-person care immediately if a side effect becomes problematic or you experience:

  • Severe nausea and/or vomiting resulting in dehydration - it is important to stay well hydrated and drink plenty of fluids while on this medication. Kidney problems/kidney failure - vomiting, nausea, diarrhea can cause dehydration and kidney issues and make kidney problems worse in individuals who have pre-existing kidney conditions; may sometimes lead to the need for hemodialysis.
  • Thyroid C-Cell Tumor: Trouble swallowing, hoarseness, a lump or swelling in your neck, or shortness of breath (see black box warning below).
  • Pancreatitis: Severe pain in your abdomen or back that will not go away.
  • Acute gallbladder disease: Pain in the middle or right upper stomach, fever, white parts of your eyes turn yellow or skin turns yellow, nausea/vomiting.
  • Hepatitis: Elevated liver enzymes/Jaundice.
  • Diabetic retinopathy problems: Changes in vision in those with type II diabetes, particularly vision problems may worsen in those with a history of diabetic retinopathy.
  • Severe gastrointestinal disease: may cause gastrointestinal disease; do not use if you have a history of severe gastrointestinal disease.
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