Tirzepatide vs Semaglutide: Key Differences & Selection Guide

When comparing medications for weight reduction, you may come across tirzepatide and semaglutide. They're the active ingredients in two different medications: Mounjaro and Wegovy, which help patients reduce body weight. That said, what's the difference between these two medicines?

Semaglutide acts on one hormone pathway, GLP-1, while Tirzepatide acts on two, GLP-1 and GIP, which is why it's called a dual agonist. A head-to-head clinical trial also showed that tirzepatide may produce greater weight loss than semaglutide.

This blog outlines other key differences between these two active ingredients and how Curely can help you pick the right one for your weight loss goals.

Key Takeaways

• Tirzepatide targets two hormone pathways (GLP-1 and GIP), while semaglutide only targets GLP-1.
• The SURMOUNT-5 study reported 20.2% weight loss with tirzepatide compared to 13.7% with semaglutide over 72 weeks.
• Semaglutide offers more administration options, as it's available as a weekly injection or daily pill, while tirzepatide is only available as a weekly injection.
• Both medications suppress appetite and can cause digestive side effects such as nausea, vomiting, constipation, and diarrhoea.
• The right medication depends on your health, budget, treatment preferences, and weight-loss goals.

Tirzepatide and Semaglutide: How They Work for Weight Loss

1. Semaglutide

Convenient once-weekly dosing

Wegovy injection

Supports appetite control and weight loss

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Semaglutide is a GLP-1 receptor agonist, meaning it imitates glucagon-like peptide-1. This is a hormone your gut releases after eating to slow the rate at which the stomach empties and signal to the brain that you're full. The hormone also prompts the pancreas to release insulin when blood glucose is high.

Appetite suppression and feeling full after a small meal can lower calorie intake, which may lead to weight loss.

Semaglutide is the active ingredient in Wegovy Injection and Wegovy pills (oral semaglutide). These are prescription drugs licensed for use in the UK for treating obesity and overweight symptoms. Patients take the injection once a week and the pills once daily, alongside lifestyle changes such as regular exercise and eating a healthy diet.

According to Novo Nordisk's Phase 3b STEP UP trial, participants lost 20.7% of their total body weight on the 7.2 mg semaglutide injection.

Note: Semaglutide is also present in Ozempic, a prescription medication for treating type 2 diabetes. While people often compare Ozempic to Mounjaro or Wegovy, the medication is not licensed for treating obesity. Using it that way would be off-label.

2. Tirzepatide

Tirzepatide is a dual receptor agonist. In addition to the GLP-1 pathway that semaglutide uses, tirzepatide also acts on glucose-dependent insulinotropic polypeptide (GIP), a second gut hormone.

The SURPASS-3 MRI Sub-study suggests that activating GIP alongside GLP-1 improves how the body handles fat and glucose. It may also improve how well patients tolerate the treatment at higher doses than GLP-1 activation alone would allow.

Tirzepatide is the active ingredient in Mounjaro. Like other weight loss injections, you take it once a week alongside a reduced-calorie diet and regular exercise for weight loss.

In the SURMOUNT trial, participants lost an average of 20.9% to 22.5% on the highest dose of tirzepatide (15 mg).

Comparison Summary: GLP-1 vs GIP/GLP-1

Tirzepatide vs Semaglutide: Head-to-Head Comparison

Both tirzepatide and semaglutide are prescribed for chronic weight management in eligible patients. Until recently, comparing the two for obesity management depended on individual clinical trials. However, the SURMOUNT-5 trial changed that.

It was the first study to compare tirzepatide and semaglutide directly in adults with obesity. According to the results, participants on tirzepatide achieved an average weight loss of 20.2% compared to 13.7% for semaglutide over 72 weeks.

However, it's important to note that some participants on semaglutide lost more than the average tirzepatide participant, and vice versa. Also, during the study, participants received lifestyle support and guidance on the right diet, which may have affected the results.

Scientists discovered the following while studying the two medications:

Cardiovascular & Off-Label Benefits

Semaglutide has dedicated FDA and MHRA approval for reducing cardiovascular disease risk (heart attack and stroke) in adults with established heart disease and obesity (based on the landmark SELECT trial). On the other hand, tirzepatide has shown significant metabolic, liver fat (MASH/NASH), and obstructive sleep apnoea benefits.

Side Effect Profiles & Tolerability

Both medications cause mild-to-moderate nausea, vomiting, constipation, or diarrhoea. These effects often worsen at the start of treatment or with dose increases. However, in the SURMOUNT-5 trial, fewer participants discontinued tirzepatide because of gastrointestinal side effects than semaglutide, suggesting GIP may improve tolerability at higher doses. However, individual experiences can still vary.

Should I Choose Tirzepatide or Semaglutide for Weight Loss?

Supports lasting weight management

Mounjaro

Safe and Secure Medication

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When comparing these two treatments, it's tempting to focus only on the SURMOUNT-5 trial key findings and assume the drug with the higher weight-loss percentage is automatically the better choice. However, selecting a medication depends on your lifestyle needs and personal goals. Consider the following:

• Health Profiles: People managing type 2 diabetes can benefit from either treatment, as both offer good glycemic control. However, semaglutide has a proven advantage for reducing cardiovascular risk, which may be more helpful to people with established heart disease.
• Format: Tirzepatide is only available as an injection, while semaglutide is available as an injection and a weight loss pill, which may be more suitable for people who are uncomfortable with needles.
• Side Effects: Some patients experience fewer side effects with tirzepatide at higher doses because of its dual action. However, note that this may not be the case for you, as individual response varies.
• Insurance Coverage: While health plans vary by provider, semaglutide often has broader insurance coverage because it's been on the market longer.
• Cost: Prices can make you choose one over the other. Mounjaro price comparisons in the UK show that tirzepatide is often more expensive than semaglutide because of higher demand and manufacturer pricing.

The best treatment choice depends on these factors, along with your overall health and weight-loss goals. Always speak with a healthcare provider to find the best treatment.

Can You Switch Between Tirzepatide and Semaglutide?

You can switch from tirzepatide to semaglutide and vice versa, but only under medical supervision. Patients usually consider switching due to:

• Plateauing on Semaglutide: Some people's weight loss stalls on the maximum dose of semaglutide, but changing to tirzepatide's dual GLP-1/GIP mechanism can restart progress.
• Managing Side Effects: Patients experiencing persistent nausea or digestive issues on one drug may tolerate the other better.
• Access and Cost: Manufacturing costs and demand can make one medication harder to access, so you can switch to maintain weight-loss progress.

Curely can help you switch between medications, starting you off at a lower dose to allow your body to get used to the new treatment and minimizing severe side effects.

Get Semaglutide and Tirzepatide from Curely

Curely offers weight-loss treatments including Mounjaro and Wegovy to eligible patients in the UK through a safe, convenient process. Complete a short online consultation covering your medical history, BMI, current medications, and weight loss goals.

One of our qualified clinicians will review it and recommend the best treatments for you. We'll explain all available options and help you choose the right one.

After approval, Curely delivers your medication to your address in unbranded packaging to protect your privacy. You'll also have access to ongoing support during your weight loss journey, so you can reach out with questions about your progress or managing side effects.

Start your consultation with Curely today.

FAQs

Is Tirzepatide Stronger Than Semaglutide?

Tirzepatide acts on two hormone pathways while semaglutide acts on one. Also, according to the SURMOUNT-5 head-to-head trial, tirzepatide produced greater average weight loss than semaglutide. However, this may not be the case for you, as individual factors such as response to treatment may affect the results. Speak to Curely for guidance on picking the right treatment.

Do You Lose More Muscle on Semaglutide or Tirzepatide?

Neither drug strictly targets muscle tissue. Patients on higher doses of either medication may start to lose muscle mass because they're losing a lot of weight quickly. Eating more protein even with reduced food intake is necessary to preserve muscle tissue. Strength training can also help.

Why Is Semaglutide Cheaper than Tirzepatide?

Semaglutide entered the market earlier and benefits from higher production volumes. Also, semaglutide is a single GLP-1 receptor agonist, whereas tirzepatide is a dual GLP-1/GIP agonist with higher production costs.

Final Thoughts

Tirzepatide and semaglutide are weight loss medications with additional benefits such as improving hypertension and reducing the risk of cardiovascular diseases. However, semaglutide is a single-receptor agonist (GLP-1), while tirzepatide is a GLP-1 and GIP receptor agonist.

According to the SURMOUNT-5 head-to-head trial, tirzepatide produced greater weight loss than semaglutide. However, this may not always be the case because results depend on factors such as response to medication.

Choosing the right treatment between the two depends on your overall health and other factors such as side effects, availability, cost, and personal preference. Speak to Curely today so we can help you choose the right treatment after a thorough medical assessment.

Reference List

• Aronne LJ, Horn DB, Le Roux CW, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. New England Journal of Medicine. 2025;393(1).
• A. Michael Lincoff, Kirstine Brown‐Frandsen, Colhoun HM, et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. The New England Journal of Medicine. 2023;389(24).
• England N. NHS England » Over a million people could be offered Wegovy to cut heart attack and stroke risk on the NHS. England.nhs.uk. April 2026.
• Knop FK, Aroda VR, Ruben, et al. Oral semaglutide 50 mg taken once per day in adults with overweight or obesity (OASIS 1): a randomised, double-blind, placebo-controlled, phase 3 trial. The Lancet. 2023;402(10403).
• Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine. 2022;387(3):205-216.
• Sattar N, Neeland IJ, Dahlqvist Leinhard O, et al. Tirzepatide and muscle composition changes in people with type 2 diabetes (SURPASS-3 MRI): a post-hoc analysis of a randomised, open-label, parallel-group, phase 3 trial. The Lancet Diabetes & Endocrinology. 2025;13(6):482-493.
• Wharton S, Freitas P, Jøran Hjelmesæth, et al. Once-weekly semaglutide 7·2 mg in adults with obesity (STEP UP): a randomised, controlled, phase 3b trial. The Lancet Diabetes & Endocrinology. Published online September 1, 2025