What is Mounjaro?
Mounjaro (tirzepatide) is a groundbreaking medication developed by Eli Lilly that represents an entirely new class in the treatment of obesity and type 2 diabetes. Unlike Ozempic and Wegovy, which work exclusively on the GLP-1 receptor, Mounjaro is the first approved dual GIP/GLP-1 receptor agonist, it simultaneously activates two incretin receptors.
GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) are both natural gut hormones released after eating. By activating both systems simultaneously, tirzepatide achieves a more powerful effect on satiety, insulin regulation, and fat metabolism than GLP-1 agonists alone.
In the SURMOUNT clinical trials, Mounjaro achieved the highest weight loss percentages ever measured in a pharmaceutical study, up to 22.5% reduction in body weight. This approaches results previously only achieved with bariatric surgery.
The Dual Mechanism of Action
What makes tirzepatide unique is the simultaneous activation of GIP and GLP-1 receptors. While semaglutide (Ozempic/Wegovy) only targets the GLP-1 system, Mounjaro adds the GIP system. GIP plays a crucial role in fat metabolism: it improves the breakdown of stored fat (lipolysis), increases thermogenesis (heat production through fat burning), and improves insulin sensitivity in adipose tissue.
This dual action results in a stronger satiety effect, more efficient metabolism, and greater reduction of visceral fat (the dangerous belly fat around organs). Clinically, this translates to the highest weight loss ever achieved with medication.
This dual mechanism of action explains why tirzepatide consistently achieves higher weight loss percentages than semaglutide alone in clinical trials.
SURMOUNT Trials: Record-Breaking Results
The SURMOUNT research program comprises four large international clinical trials with over 5,000 participants in total. The results surpass all previous pharmaceutical interventions for weight loss.
Average 20.9% weight loss after 72 weeks (15 mg dose). 36% of participants lost more than 25% body weight.
Average 14.7% weight loss in patients with type 2 diabetes, significantly higher than semaglutide in comparable populations.
Average 26.6% weight loss combined with intensive lifestyle intervention, the highest ever measured.
Patients who switched to placebo after initial loss regained 14%, vs 0% with tirzepatide continuation.
The SURMOUNT-1 results are historic: average weight loss of 22.5% at the highest dose. More than one-third of participants achieved weight loss exceeding 25%, a feat that blurs the line between pharmacotherapy and surgery.
Clinical Results (SURMOUNT-1)
| Treatment Group | Weight Loss | ≥5% | ≥10% | ≥15% | ≥20% |
|---|---|---|---|---|---|
| Tirzepatide 15 mg | -22.5% | 96% | 84% | 68% | 39% |
| Placebo | -2.4% | 28% | 10% | 4% | 1% |
Jastreboff A.M. et al., N Engl J Med. 2022;387:327-340
Results may vary per individual and depend on lifestyle and metabolism.
Dosage & Titration Schedule
Mounjaro is titrated in 2.5 mg increments. The maximum dose is 15 mg per week. Your physician may adjust the schedule based on tolerability.
| Period | Dosage | What to expect |
|---|---|---|
| Week 1–4 | 2.5 mg/week | Starting dose, the body adjusts to tirzepatide |
| Week 5–8 | 5.0 mg/week | First escalation, appetite reduction noticeable |
| Week 9–12 | 7.5 mg/week | Therapeutic effect becomes stronger |
| Week 13–16 | 10.0 mg/week | Further build-up |
| Week 17–20 | 12.5 mg/week | Build-up toward maximum dose |
| Week 21+ | 15.0 mg/week | Maximum maintenance dose |
Visual Dosage Timeline
Mounjaro — How the dosage is built up step by step
Starting dose — the body adjusts to tirzepatide
First escalation — appetite reduction noticeable
Therapeutic effect becomes stronger
Further build-up
Build-up toward maximum dose
Maximum maintenance dose
This schedule is indicative. Your physician adjusts the dosage based on your individual response and tolerability.
Injection Instructions
Injection sites
- Abdomen (front, around the navel)
- Upper thigh
- Upper arm (outer side)
Rules
- Inject subcutaneously (under the skin), not into a vein or muscle
- Rotate injection sites weekly to prevent skin irritation
- Use the same day each week for your injection
Always have a physician or nurse supervise your first injection.
Storing Mounjaro
In the refrigerator (2–8°C). Do not freeze. Protect from light.
Maximum 21 days at room temperature (maximum 30°C). Note: this is shorter than Wegovy/Ozempic.
Dispose of the pen in a sharps container after use. Do not discard with household waste.
Missed Dose
Administer the dose and resume your normal schedule.
Skip the missed dose and take the next one on the usual day.
Never take a double dose to make up for a missed injection.
Side Effects
Mounjaro's side effect profile is comparable to GLP-1 monotherapy, although the frequency of gastrointestinal complaints may be slightly higher due to dual receptor activation.
Very common (>10%)
- Nausea (24-33%)
- Diarrhea (21-25%)
- Decreased appetite (20%)
- Vomiting (9-13%)
- Constipation (11-17%)
Common (1–10%)
- Indigestion
- Flatulence
- Reflux
- Fatigue
- Dizziness
- Injection site reaction
- Hair loss (with rapid weight loss)
Serious (contact your physician)
- Persistent severe abdominal pain (possible pancreatitis)
- Severe nausea/vomiting/diarrhea (risk of dehydration)
- Pain in upper right abdomen (possible gallbladder problems)
- Swelling of face, lips or tongue (allergic reaction)
Tips for GI complaints
- Follow the titration schedule strictly, do not skip steps
- Eat smaller portions spread throughout the day
- Avoid fatty and spicy food in the first weeks
- Drink small sips of water regularly
Contraindications
Mounjaro should not be used in the following situations:
- Hypersensitivity to tirzepatide or any of the excipients
- Severe gastrointestinal conditions (such as gastroparesis)
- Personal or family history of medullary thyroid carcinoma (MTC) or MEN2
- Under 18 years of age
- Pregnancy or breastfeeding (stop at least 2 months before planned pregnancy)
- Concurrent use with other GLP-1 or GIP agonists
Insurance & Reimbursement
- Mounjaro is registered for type 2 diabetes. For weight loss, it is not covered by basic health insurance.
- Consult your health insurer for supplementary coverage.
Go Leaner offers transparent all-in-one pricing with no surprises.
Composition
| Active substance | Tirzepatide |
| Type | Dual GIP/GLP-1 receptor agonist |
| Manufacturer | Eli Lilly |
Mounjaro vs Ozempic & Wegovy
The key differences: Mounjaro is a dual GIP/GLP-1 agonist (vs GLP-1 only), achieves higher weight loss percentages (20-22.5% vs 12-17%), and has a broader dosing range. The dual receptor mechanism makes it particularly effective for patients who plateau on semaglutide.
Comparison of all three medications →
Mounjaro at Go Leaner
As a digital clinic, we offer Mounjaro as a premium option for patients seeking maximum effectiveness, or for those where previous GLP-1 monotherapy has yielded insufficient results. Your physician at Go Leaner determines whether Mounjaro is the right choice based on your medical profile, BMI, and treatment history.
Nutrition and more information
Nutrition is essential during GLP-1 treatment. Read our guide for practical tips on nutrition, proteins, and lifestyle:
Nutrition and Lifestyle During GLP-1 Treatment →
Official Patient Leaflet — Mounjaro
Patient information from the European Medicines Agency (EMA)
Download the official Dutch-language patient information leaflet (PIL) for Mounjaro (tirzepatide). This document contains complete information about usage, dosage, side effects, contraindications and storage instructions, as approved by the European Medicines Agency (EMA).
Source: European Medicines Agency (ema.europa.eu)
Frequently Asked Questions
Mounjaro is een receptplichtig geneesmiddel. Gebruik uitsluitend onder medisch toezicht. Deze informatie is informatief en vervangt geen medisch advies.
Sources
- 1.EMA SmPC Mounjaro (tirzepatide), European Medicines Agency
- 2.SURMOUNT-1 Study (PubMed), Jastreboff A.M. et al., N Engl J Med. 2022;387:205-216 — DOI: 10.1056/NEJMoa2206038
- 3.CBG-MEB Medicines Database, Medicines Evaluation Board