Weight loss
Mounjaro (tirzepatide) treatment guide
Everything you need to know about your Mounjaro treatment — how to inject, your dose schedule, managing side effects, and when to contact your doctor.
01 / 10
How to use
- 01
Step 1
Choose your injection site
Rotate between abdomen, thigh, or upper arm each week. Clean the area with an alcohol swab and let it dry.
- 02
Step 2
Inject at the same time each week
Pick a day that works for you. If you forget a dose, take it within 4 days of the missed dose. If more than 4 days have passed, skip that dose and take your next one on the regular scheduled day.
- 03
Step 3
Use a new needle each time
Remove the needle after each injection and dispose of it safely in a sharps container. Never reuse needles.
- 04
Step 4
Subcutaneous injection
Mounjaro is injected just under the skin (subcutaneous). Do not inject into a vein or muscle. Use the abdomen, thigh, or upper arm. The injection pen delivers the full dose — hold it in place for 5 seconds after the click.
02 / 10
Treatment pathway
Your Mounjaro pathway
Weeks 1-4
Start at 2.5 mg once weekly
This step is for tolerability, not weight loss — your body adapts to the medicine.
From week 5
Increase step by step
5 mg, then 7.5 mg, then 10 mg, 12.5 mg and 15 mg — each step held for at least 4 weeks.
- Move up only if the current dose is well tolerated
- Many people maintain on 5-10 mg without ever reaching 15 mg
After 3 months on your maintenance dose — have you lost at least 5% of your starting weight?
Yes
Continue treatment
Keep the same dose and your 3-monthly reviews.
No
Doctor review
Your prescriber may adjust the dose, switch medicines or revisit the plan.
From week 5
Every dose change is doctor-reviewed. Never change your dose without confirmation.
03 / 10
Dose schedule
Dose schedule
2.5 mg weekly
Weeks 1-4
5 mg weekly
Weeks 5-8
7.5 mg weekly
Weeks 9-12
10 mg weekly
Weeks 13-16
12.5 mg weekly
Weeks 17-20
Maintenance dose
15 mg weekly
Week 21+
- Starting dose to help your body adjust.
- First step-up dose.
- Second step-up.
- Continue building up.
- Penultimate step.
- Maximum maintenance dose.
04 / 10
How it compares
| Prescription weight-loss medicines at a glance | How it works | Dosing | Route | Dose steps |
|---|---|---|---|---|
| Mounjaro (tirzepatide) | Dual GIP + GLP-1 receptor agonist | Once weekly | Injection under the skin | 2.5 to 15 mg over 5+ months |
| Wegovy (semaglutide) | GLP-1 receptor agonist | Once weekly | Injection under the skin | 0.25 to 2.4 mg over 4+ months |
| Saxenda (liraglutide) | GLP-1 receptor agonist | Once daily | Injection under the skin | 0.6 to 3.0 mg over 4+ weeks |
| Rybelsus (semaglutide) | GLP-1 receptor agonist | Once daily, empty stomach | Tablet by mouth | 1.5 to 9 mg over 2+ months |
All four require the same lifestyle foundation: reduced-calorie diet and increased physical activity. Your prescriber chooses based on your history, preferences and response. Rybelsus is licensed for type 2 diabetes and may be prescribed off-label for weight management where your doctor judges it appropriate.
05 / 10
Side effects
Nausea
Very common in the first weeks. Eat smaller meals, avoid fatty or fried foods, and eat slowly. Nausea usually improves within 1-2 weeks.
Constipation or diarrhoea
Drink plenty of water (6-8 glasses a day). Include fibre-rich foods like vegetables and whole grains. Gentle movement like walking can help.
Fatigue
Some patients feel tired in the first weeks. This usually passes. Rest when needed and keep your meals light.
When to seek help
Contact your doctor if you have severe abdominal pain that does not go away, persistent vomiting, signs of an allergic reaction (rash, itching, swelling), or any symptom that worries you.
06 / 10 · Do not use if
- Allergy to tirzepatide or any ingredient of Mounjaro
- Personal or family history of medullary thyroid cancer or MEN 2 syndrome
- History of pancreatitis
- Pregnancy, planned pregnancy or breastfeeding
- Severe stomach or bowel disease, including gastroparesis
- Type 1 diabetes or a history of diabetic ketoacidosis
This list is not exhaustive — your questionnaire and prescriber review decide whether Mounjaro is safe for you.
07 / 10 · When to contact your doctor
Contact your doctor if
- Severe or persistent nausea, vomiting, or diarrhoea that prevents you from eating or drinking
- Severe abdominal pain that does not go away
- Signs of an allergic reaction (rash, itching, swelling of the face or throat)
- Any symptom that worries you or feels unusual
08 / 10
Storage
Store unused pens in the refrigerator (2-8°C). Once opened, keep at room temperature below 30°C for up to 30 days. Do not freeze. Keep away from direct heat and light.
09 / 10
What to expect
Most patients notice reduced appetite within 2-4 weeks. Clinically meaningful weight loss is assessed at 3 months. A loss of 5% or more of your starting weight at 3 months is considered a good response. Your doctor will review your progress quarterly.
10 / 10