Mounjaro Dosage Guide: From Starter Dose to Maintenance
If you’ve just been prescribed Mounjaro, or you’re about to move up a dose level, this Mounjaro dosage guide covers everything you need: the starting dose, the titration schedule, maintenance options, and what to do when things don’t go to plan. Mounjaro is a prescription-only medication, and a consultation is required before starting or changing your dose. For a broader overview of your options, see our weight loss treatments hub.
What the mounjaro dosage guide covers: the basics
Mounjaro (tirzepatide) is a once-weekly injectable medication approved for weight management and type 2 diabetes. It works by mimicking two gut hormones, GIP and GLP-1, which regulate appetite, blood sugar, and digestion. Because it has a pronounced effect on the gut, the dosing protocol is specifically designed to let your body adjust gradually.
There are six available dose strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg. Each comes in a pre-filled pen containing a single dose. You cannot split or adjust the dose within a pen, and attempting to do so is unsafe.
The maximum dose for adults is 15 mg per week. For young people aged 12 to 17, the maximum is 10 mg. No dose-adjustment is officially required for kidney or liver disease in mild to moderate cases, though your prescriber will apply clinical judgement in more complex situations.
The standard mounjaro dosage guide: titration schedule
The titration schedule below reflects the manufacturer’s guidance:
| Phase | Dose | Duration |
| Initiation | 2.5 mg | Weeks 1 to 4 |
| First increase | 5 mg | Weeks 5 to 8 |
| Second increase | 7.5 mg | Weeks 9 to 12 |
| Third increase | 10 mg | Weeks 13 to 16 |
| Fourth increase | 12.5 mg | Weeks 17 to 20 |
| Maximum | 15 mg | Week 21 onwards |
Each dose level runs for at least four weeks before you move up. There is no obligation to reach 15 mg. Many people find an effective, tolerable maintenance dose at 5 mg or 10 mg and stay there long-term, with their prescriber’s agreement.
The 2.5 mg starting dose
The 2.5 mg dose is not intended to produce meaningful weight loss or blood sugar control. Its purpose is tolerability: it allows your digestive system to adapt before the dose increases. Expect minimal effect on appetite at this stage. Nausea, loose stools, and reduced hunger are the most commonly reported side effects in the early weeks.
When to move up
Your prescriber will review your progress at each four-week interval. The main questions are: are side effects manageable? Is there evidence of glycaemic improvement or weight reduction? If you’re struggling with ongoing nausea or vomiting, it’s reasonable to stay at your current dose for longer, or even step back down temporarily. There is no clinical requirement to escalate on a fixed timeline.
Maintenance doses: which one is right for you?
The three main maintenance doses are 5 mg, 10 mg, and 15 mg, though people do maintain successfully on 7.5 mg or 12.5 mg as well. Clinical trial data from the SURMOUNT-1 study gives a useful reference point for average weight loss at each level:
- 5 mg: approximately 15% body weight reduction over 72 weeks
- 10 mg: approximately 19.5% body weight reduction over 72 weeks
- 15 mg: approximately 20.9% body weight reduction over 72 weeks
The difference between 10 mg and 15 mg is smaller than many expect. If you’re tolerating 10 mg well and seeing good results, there is no medical need to push higher. Equally, if 15 mg causes persistent side effects, stepping back to 12.5 mg is a reasonable clinical decision.
To be eligible for Mounjaro for weight management in the UK, you typically need a BMI of 30 or above, or a BMI of 27 or above with at least one weight-related health condition.
Practical situations the schedule doesn’t cover
Missed injections
If you miss your weekly dose, inject it as soon as you remember, provided it is within four days of the missed date. If more than four days have passed, skip that dose and resume on your next scheduled day. Never inject two doses within 72 hours of each other.
Switching from another GLP-1
If you’re moving to Mounjaro from semaglutide (Ozempic or Wegovy) or liraglutide (Saxenda), you always restart at 2.5 mg, regardless of your previous dose. Dose equivalence does not transfer between medications, and the titration schedule exists for safety reasons. Do not attempt to match doses across drug classes.
Lowering your dose
Most dosage guides only cover going up. In practice, stepping down is sometimes the right move. If you’ve moved to 10 mg and find the nausea unmanageable, a temporary return to 7.5 mg is appropriate. Some people discover that a lower dose delivers acceptable results with far fewer side effects and choose to maintain there. This is clinically reasonable.
Combining with other diabetes medications
If you take insulin or a sulfonylurea alongside Mounjaro, your prescriber may recommend a lower dose of those medications to reduce hypoglycaemia risk. Mounjaro itself does not typically cause low blood sugar when used alone, but combinations require monitoring.
Injection timing and storage
Mounjaro is injected once weekly, on any day, at any time, with or without food. Pick a day and stick to it. If you want to change your injection day, leave at least three days between doses when making the switch.
For full step-by-step guidance on technique, rotation sites, and pen use, read our article on how to inject Mounjaro.
Storage: Keep pens refrigerated at 2°C to 8°C. Do not freeze. If kept at room temperature (below 30°C), a pen can be used for up to 21 days. Discard any pen that has been frozen or left in direct sunlight.
Summing Up
The Mounjaro dosing schedule is not a rigid target to chase; it is a framework. Most people start at 2.5 mg, work up gradually over several months, and find a maintenance dose that balances results with tolerability. That might be 5 mg, 10 mg, or 15 mg. It might mean stepping back down at some point. None of that represents failure; it represents the medication working as intended, adjusted for you.
Always discuss any dose changes with your prescriber before making them. Do not alter your schedule based on what someone else is doing or what you’ve read on a forum.
If you’re ready to start or continue your treatment, you can order Mounjaro through Star Pharmacy’s online weight loss management following a clinical consultation.
FAQs
Can I start at 5 mg instead of 2.5 mg?
No. All patients start at 2.5 mg, regardless of body weight, previous GLP-1 use, or urgency. The starting dose is not about efficacy; it is about reducing the risk of severe gastrointestinal side effects in the first weeks of treatment.
What if 5 mg is working well? Do I have to keep increasing?
You do not. If you are losing weight steadily, tolerating the medication well, and your prescriber agrees, 5 mg can be your long-term maintenance dose. Clinical data shows an average body weight reduction of around 15% at this level.
Is there a leftover dose in the pen after I inject?
No. Pre-filled Mounjaro pens contain one dose plus a small safety margin of liquid. The residual volume is not usable. Do not attempt a second injection from the same pen.
What happens if I inject twice in one week by mistake?
Contact your prescriber or a pharmacist promptly. A double dose is unlikely to be life-threatening, but it significantly increases the risk of severe nausea, vomiting, and low blood sugar if you are also on insulin. Monitor for symptoms and seek advice.
Can I change my injection day?
Yes, but leave a minimum of three days between the two injections when making the switch. For example, if you normally inject on Wednesday and want to move to Saturday, your next dose should be no earlier than Saturday to preserve the spacing.
Do I need to stop Mounjaro if I’m having an operation?
Discuss this with your surgical team. Some anaesthetists recommend pausing GLP-1 medications before general anaesthesia due to the risk of delayed gastric emptying. There is no universal protocol, so follow your surgeon’s or anaesthetist’s specific advice.