Introduction: why the choice between Wegovy and Mounjaro matters
Obesity is a chronic disease affecting millions of people in Romania and worldwide. In recent years, the development of GLP-1 receptor agonists has revolutionised obesity treatment, offering significant weight-loss results. Two of the most discussed medicines in this class are Wegovy (semaglutide) and Mounjaro (tirzepatide).
The weekly injectable forms of these medicines are administered subcutaneously and have demonstrated remarkable effectiveness in clinical studies. However, they differ in mechanism of action, effectiveness profile and side effects. This guide helps you understand the essential differences so you can make an informed decision with your doctor.
If you want to discuss these treatments with a specialist, you can book an online nutrition consultation directly on our platform.
What is Wegovy (semaglutide)?
Wegovy contains semaglutide, a GLP-1 (glucagon-like peptide-1) receptor agonist. It was approved for chronic weight management in adults with obesity (BMI ≥ 30 kg/m²) or overweight (BMI ≥ 27 kg/m²) with at least one weight-related comorbidity.
Semaglutide mimics the natural hormone GLP-1, released by the intestine after a meal. This hormone has several important effects:
Reduced appetite – acts on the brain's satiety centres (hypothalamus), helping you feel full sooner and for longer
Slower gastric emptying – food stays in the stomach longer, prolonging fullness
Stimulated insulin release – helps regulate glucose and also benefits people with prediabetes or type 2 diabetes
Reduced glucagon production – contributes to maintaining normal glucose levels
The Wegovy dose and gradual increases are determined according to the prescribed formulation, current EMA information and the doctor's recommendation. Do not change your dose based on a general guide.
What is Mounjaro (tirzepatide)?
Mounjaro contains tirzepatide, a unique medicine acting as a dual agonist of GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptors. Its dual mechanism potentially offers additional advantages:
Dual GLP-1 + GIP action – GIP has complementary metabolic effects, including improving insulin sensitivity and directly influencing fat tissue
Significant appetite reduction – through synergistic mechanisms in the brain
Improved lipid metabolism – significant reductions in triglycerides and cholesterol
Enhanced weight effect – studies suggest greater weight loss than with single GLP-1 agonists
The maximum Mounjaro dose is 15 mg weekly, with gradual escalation starting at 2.5 mg.
Comparing effectiveness: STEP vs SURMOUNT clinical studies
STEP studies (Wegovy / semaglutide)
The STEP clinical programme included several large studies with thousands of participants. Key STEP results showed:
STEP 1 – average loss of 14.9% of body weight after 68 weeks in participants without diabetes, compared with 2.4% on placebo
STEP 2 – average loss of 9.6% in participants with type 2 diabetes
STEP 3 – combining treatment with intensive behavioural therapy led to a 16.0% loss
STEP 5 – maintaining weight loss long term, over 2 years: −15.2%
The SELECT study also demonstrated a 20% reduction in major cardiovascular events (heart attack, stroke and cardiovascular death) in patients with obesity and pre-existing cardiovascular disease.
SURMOUNT studies (Mounjaro / tirzepatide)
The SURMOUNT programme evaluated tirzepatide at doses of 5, 10 and 15 mg:
SURMOUNT-1 – average loss of 20.9% of weight at 15 mg after 72 weeks, compared with 3.1% on placebo. More than 50% of participants lost ≥20% of their weight
SURMOUNT-2 – in participants with type 2 diabetes: a 14.7% loss at 15 mg
SURMOUNT-3 – combining treatment with intensive lifestyle intervention: a 26.6% loss
SURMOUNT-4 – demonstrated weight regain after stopping treatment and maintenance of results when continuing
The direct comparison: SURMOUNT-5
The randomised SURMOUNT-5 study compared tirzepatide with semaglutide in adults with obesity without type 2 diabetes over 72 weeks. Average weight change was −20.2% versus −13.7%. The study used the protocol's maximum tolerated doses and was open-label; results do not compare every formulation or dose available today and do not predict any individual's response. Original SURMOUNT-5 publication (NEJM, 2025).
Comparative conclusion on effectiveness
Interpreting the comparison requires considering the specific study, population, duration and doses. STEP and SURMOUNT results should not be compared as though they came from the same population; SURMOUNT-5 provides a direct comparison under the conditions described above.
Comparing side effects
Both medicines have a similar side-effect profile, predominantly gastrointestinal, particularly during dose escalation:
Side effects common to both medicines
Nausea – a frequently reported digestive reaction that usually improves over time
Diarrhoea – may occur during treatment
Constipation – may occur during treatment
Vomiting – less frequent, but possible, especially with a dose increase
Abdominal pain – usually mild and temporary
Headache and fatigue – usually during the first weeks
Notable differences
Frequencies differ between medicines, doses and study populations. Consult the current leaflet for side effects and discuss persistent or intense symptoms with your doctor.
Assessment before treatment: this includes contraindications and precautions in the medicine's EU information, allergies, medical history, current treatments and pregnancy plans. Tell the doctor about any history of pancreatitis, severe digestive conditions and your personal or family thyroid history.
Prices in Romania (2026)
Prices can vary by pharmacy and availability. As a guide, in Romania:
Wegovy — check the pharmacy price for the prescribed formulation and dose.
Mounjaro — check the pharmacy price for the prescribed formulation and dose.
Reimbursement conditions need checking for the indication and prescribed treatment; do not assume authorisation means reimbursement. To discuss treatment options, book an online consultation with Dr. Petrache directly on our platform.
Who is each medicine suitable for?
Eligibility and treatment choice depend on the authorised indication, medical history, other treatments and tolerability. A target number of kilograms or an average study result does not determine the choice of medicine by itself.
How do you choose between Wegovy and Mounjaro?
The choice between the two medicines should always be made with a specialist doctor, who will assess:
Body mass index (BMI) and target weight
The presence of type 2 diabetes or prediabetes
Associated cardiovascular disease
Lipid profile and other comorbidities
Medical history and contraindications
Budget and accessibility
Personal preferences and lifestyle
Never start these treatments without consulting a doctor. Regular medical monitoring is essential throughout treatment.
You can discuss your weight-loss treatment options through an online consultation with Dr. Petrache. A personalised nutrition plan can also effectively complement medication.
Frequently asked questions
Can I take Wegovy or Mounjaro without a diet?
The authorised weight-management indication combines treatment with a reduced-calorie diet and physical activity. The plan is adapted medically; the medicine does not replace these measures.
How long does treatment last?
Obesity is chronic, and treatment is usually long term. Studies show that stopping the medicine leads to regaining a significant part of the weight lost.
Can I switch from Wegovy to Mounjaro or the other way round?
Any switch should be discussed with the doctor. Do not combine the medicines, convert doses yourself or restart after a break without medical instructions.
Are they available in Romanian pharmacies?
EU authorisation does not guarantee local stocks. Check the prescribed formulation and dose's availability at the pharmacy; dispensing requires a prescription.
Conclusion
Both medicines have authorised indications for weight management. Benefits, risks and the limits of comparative data should be discussed with your doctor in the context of your situation.
The most important step is to speak with a specialist who can guide you towards appropriate treatment. Book an online consultation on Clinica Virtuală for personalised recommendations.
Official information for verification
EMA — current EU information for Wegovy. For tirzepatide: EMA — Mounjaro. Discuss indications and precautions with the doctor.
