You have undoubtedly heard the names mentioned. In the newspaper, at the coffee machine, perhaps from your GP. Ozempic, Wegovy, Mounjaro, Saxenda—they are all mentioned in the same breath as the ‘weight loss jab’. But are they the same drugs? And if they differ, in what way?
This is a question I receive almost daily as a pharmacist. And honestly, it is confusing. Even people who have already started a course of treatment sometimes do not know exactly what is in their prescription or why that particular medication was chosen.
In this article, I objectively compare the four most important GLP-1 medicines: the active ingredient, their registered uses, injection frequency, and what science says about their effectiveness. No sales pitch, no ‘best remedy’—that doesn’t exist. Just clarity, so you can have a better conversation with your doctor.
⚠️ Important legal framework: This article is intended solely as factual education. It is not an advertisement for a specific medicine and not a recommendation for one medicine over another. The mentioned medicines are prescription medicines; the choice and prescription are reserved exclusively for a qualified doctor, based on your individual situation. Always consult a doctor or pharmacist for personal advice.
What do they have in common? All four work under the GLP-1 system.
Let’s start with the similarities. All four agents mentioned belong to the class of GLP-1 receptor agonists or an extension thereof. As you read in blog 2, this class works on three fronts: delayed gastric emptying, inhibition of the hunger center in the brain, and more stable blood sugar.
The differences lie in four things: the active ingredient, the indication for which they are registered, how often you inject, and the strength of the effect in clinical studies. It is like with cars: they all drive, but the engine, the fuel type, and what they are made for differ.
The comparison at a glance
The table below shows the key differences. The figures mentioned are from published phase 3 studies.
| Brand Name | Brand NameActive IngredientRegistered ForWeight Loss in StudiesFrequency | Registered For | Weight Loss in Studies | Frequency |
|---|---|---|---|---|
| Ozempic® | Semaglutide | Type 2 Diabetes | Not registered for weight loss | 1× per week |
| Wegovy® | Semaglutide | Obesity / Overweight with comorbidities | ~14.9% after 68 weeks | 1× per week |
| Mounjaro® | Tirzepatide | Type 2 Diabetes; Obesity (in EU) | ~15–22.5% after 72 weeks | 1× per week |
| Saxenda® | Liraglutide | Obesity / Overweight with comorbidities | ~8% after 56 weeks | Daily |
| The study results were obtained in combination with a lifestyle intervention (nutrition, exercise, guidance). The figures do not constitute an individual guarantee; effectiveness varies per person. | ||||
The four remedies, one by one
Ozempic® the well-known name from the news
Ozempic contains semaglutide and is registered in Europe for the treatment of type 2 diabetes. It is therefore formally not a weight-loss drug. Ozempic became so well-known because people with diabetes who used Ozempic also lost significant weight. This additional observation led to follow-up research with a higher dosage of the same substance, which became Wegovy.
The fact that Ozempic is sometimes prescribed by doctors ‘off-label’ for weight loss is a subject of discussion within the medical profession. Off-label use means that a doctor prescribes a medication for something other than that for which it was approved; this is only permitted in specific circumstances and after careful consideration.
Please note: why do you receive Ozempic instead of Wegovy at some companies?
In practice, it happens that weight loss and lifestyle clinics in the Netherlands prescribe Ozempic to people who want to lose weight, even though Wegovy is the drug formally approved for that purpose. The reason is almost always financial: Ozempic is significantly cheaper per month than Wegovy (roughly €150–€250 versus €250–€480 per month, as of 2026). That price difference can be tempting for both the clinic and the patient. However, it does not change what the law states.
What does the law say?
According to Article 68, paragraph 1 of the Medicines Act, a doctor may only prescribe a medication off-label if protocols or standards exist within the medical profession that substantiate this use, or (when these are under development) after consultation with a pharmacist. This is not the case for prescribing Ozempic as a weight-loss medication: both the Dutch College of General Practitioners (NHG) and the Medicines Evaluation Board (CBG) urge doctors not to prescribe Ozempic off-label for weight loss.
Legal-scientific analyses in the Nederlands Juristenblad (2024) and the Nederlands Tijdschrift voor Geneeskunde (2024) explicitly conclude that the off-label prescribing of Ozempic for weight loss does not fall within the legal framework. This does not mean that it is punishable by definition, but it does mean that the physician is in a legally vulnerable position and can be held accountable under disciplinary law.
Our position at Easly:
If semaglutide is chosen for weight loss, we prescribe Wegovy. This is not only the legally correct route, but it is also a matter of due care and collegial responsibility.
Wegovy® same substance, specifically for weight loss
Wegovy also contains semaglutide with exactly the same active ingredient as Ozempic. The difference lies in two things: the registration and the dosage. Wegovy has been specifically approved by the European Medicines Agency (EMA) for the treatment of obesity or overweight with weight-related health problems, and is available in a higher maximum dosage (up to 2.4 mg per week).
In the STEP 1 registration study, published in The New England Journal of Medicine (2021), participants lost an average of 14.9% of their body weight after 68 weeks in combination with a lifestyle intervention.
Please note: In the Netherlands (as of 2025), Wegovy is not reimbursed under basic health insurance for the indication obesity.
Mounjaro® the newer dual action
Mounjaro contains tirzepatide and is different from the other three in that sense: it is not only a GLP-1 receptor agonist, but also a GIP receptor agonist.
What does that mean in practice? In addition to the GLP-1 hormone you are already familiar with, tirzepatide also mimics GIP hormone, a second gut hormone that is also involved in appetite and blood sugar. Studies show that the combination of both effects appears to lead to more potent results. In the SURMOUNT-1 study (NEJM, 2022), participants lost an average of 15% (5 mg dose) to 22.5% (15 mg dose) of their body weight after 72 weeks of treatment.[4] A follow-up study over 3 years (176 weeks) showed that most participants largely retained this weight with continued treatment.
Mounjaro was originally registered for type 2 diabetes and has since also received European approval for the treatment of obesity. Mounjaro is also a prescription medicine, and the prescribing physician determines whether it is a suitable option for your situation.
Saxenda® the daily option
Saxenda contains liraglutide and was for a long time the only GLP-1 agonist specifically registered for weight reduction in Europe. Its action is similar to the other agents, but liraglutide has a shorter duration of action, which means you must inject daily instead of weekly.
In clinical research, Saxenda leads to an average weight loss of approximately 8% after 56 weeks. This is less than semaglutide or tirzepatide, but Saxenda now has more long-term experience and is one of the options mentioned in the NHG Standard for Obesity (2025).
What determines which product is suitable for you?
A frequently asked question is: ‘Which medication is best?’ The honest answer is: that depends on your personal situation. Below, I list the factors that your doctor or pharmacist takes into account.
- Medical indication: Do you have type 2 diabetes, obesity, or both? This determines which medication falls within the registration.
- BMI and comorbidity: The NHG Standard (2025) uses specific threshold values for considering drug treatment.[8]
- Contraindications: For example, a personal or family history of medullary thyroid carcinoma or MEN-2 syndrome excludes GLP-1 medication.
- Practical preference: Weekly injections versus daily injections; both have advantages and disadvantages.
- Costs and availability: Not all medications are reimbursed, and prices vary considerably.
- Previous experience and side effects: If a previous medication was not well tolerated, a switch may sometimes be possible.
These are exactly the topics you discuss during a medical intake. Not ‘which pen would you like today’, but: is this medication, or GLP-1 medication in general, right for you?
Three misunderstandings I often hear
Misunderstanding 1: “Ozempic is a weight loss drug”
Ozempic is not registered in the Netherlands and Europe for weight loss, but for type 2 diabetes. The hype surrounding Ozempic has obscured this picture and has even led to shortages for diabetes patients who genuinely need the medication. Anyone seeking a prescription for weight loss is formally on Wegovy (if semaglutide is chosen).
Misunderstanding 2: “The stronger the effect, the better the remedy”
It is tempting to view Mounjaro as the ‘best’ due to the higher weight loss percentage in studies. However, stronger does not automatically mean suitable for everyone. Greater effect can also mean more side effects, and some people tolerate a less potent product better. The goal is responsible weight loss, not maximum weight loss.
Misunderstanding 3: “If I stop, the weight loss will be maintained”
This is perhaps the most important misconception. In both the STEP 1 extension and real-world data, it is clear that after discontinuation of GLP-1 medication, a large portion of the lost weight often returns unless there is long-term lifestyle change. This is not a failure: it shows that obesity is a chronic condition, just like high blood pressure.
The conclusion: there is no ‘best’, there is a ‘suitable’
Ozempic, Wegovy, Mounjaro, and Saxenda each have their own profile. What works perfectly for one person is not the right choice for another. Science provides the evidence; your doctor translates that to your individual situation; your pharmacist guides you in its use.
As a pharmacist, it costs me no effort to be clear about this: if someone has a conversation with me about GLP-1 medication, that person is entitled to honest information, including all sides of the story.
Next blog: is GLP-1 right for me?
Now that you know the differences, the next question might be: is GLP-1 medication suitable for my situation? In blog 4, we will go through the criteria: BMI limits, comorbidities, contraindications, and when a doctor will or will not consider it.
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Sources:
Wetenschappelijke artikelen
- Drucker DJ. Mechanisms of Action and Therapeutic Application of Glucagon-Like Peptide-1. Cell Metabolism. 2018;27(4):740-756. DOI: 10.1016/j.cmet.2018.03.001
- Müller TD, Finan B, Bloom SR, et al. Glucagon-like peptide 1 (GLP-1). Molecular Metabolism. 2019;30:72-130. DOI: 10.1016/j.molmet.2019.09.010
- Wilding JPH, Batterham RL, Calanna S, et al.; STEP 1 Study Group. Once-Weekly Semaglutide in Adults with Overweight or Obesity. New England Journal of Medicine. 2021;384(11):989-1002. DOI: 10.1056/NEJMoa2032183
- Jastreboff AM, Aronne LJ, Ahmad NN, et al.; SURMOUNT-1 Investigators. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine. 2022;387(3):205-216. DOI: 10.1056/NEJMoa2206038
- Aronne LJ, Horn DB, le Roux CW, et al. Tirzepatide as compared with semaglutide for the treatment of obesity. SURMOUNT-5. New England Journal of Medicine. 2025. DOI: 10.1056/NEJMoa2416394
Nederlandse richtlijnen en kaders
- Farmacotherapeutisch Kompas. Preparaatteksten semaglutide, tirzepatide, liraglutide. Zorginstituut Nederland. Beschikbaar via: farmacotherapeutischkompas.nl
- Zorginstituut Nederland. GVS-advies semaglutide (Wegovy®) bij behandeling van obesitas. 2024. Beschikbaar via: zorginstituutnederland.nl
- NHG-Standaard Obesitas (versie 2.0, herzien). Nederlands Huisartsen Genootschap. Oktober 2025. Beschikbaar via: richtlijnen.nhg.org/standaarden/obesitas
