Mounjaro Dosage Guide UK: Chart, Doses & What to Expect
If you've been prescribed Mounjaro, one of the first things you'll want to understand is the dosage. How much do you actually take? When does it go up? And what does each dose feel like?
These are the questions we hear constantly. And they matter, because Mounjaro's dosing schedule isn't one-size-fits-all. It's a stepped process, carefully designed to let your body adjust while gradually increasing the medication's effect. Getting comfortable with how it works takes some of the uncertainty out of the process.
At a glance
- Mounjaro (tirzepatide) comes in six doses: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg and 15 mg
- Everyone starts on 2.5 mg for at least four weeks
- Doses increase in 2.5 mg steps, typically every four weeks, based on how you respond
- The maximum dose is 15 mg per week, though many people find their ideal dose lower than that
- Each dose comes as a pre-filled pen
The full Mounjaro dosage chart
Mounjaro uses a tiered dosing structure. You start low and work your way up. Here's what each level looks like:
| Dose | Volume per injection | Pen colour | Purpose |
|---|---|---|---|
| 2.5 mg | 0.5 ml | Purple | Starting dose — allows your body to adjust |
| 5 mg | 0.5 ml | Blue-green | First therapeutic dose for weight loss |
| 7.5 mg | 0.5 ml | Yellow | Intermediate step if 5 mg isn't enough |
| 10 mg | 0.5 ml | Green | Higher therapeutic dose |
| 12.5 mg | 0.5 ml | Grey | Increased dose for continued progress |
| 15 mg | 0.5 ml | Dark blue | Maximum available dose |
Every Mounjaro pen delivers exactly 0.5 ml regardless of the dose strength. The concentration changes, not the volume. That's worth knowing if you've seen questions about Mounjaro dosage in ml floating around online — 0.5 ml is the answer at every level.
Mounjaro dosage in units
If you're used to insulin or other injectables, you might be wondering about Mounjaro dosage in units. Here's the thing: Mounjaro KwikPens don't use a unit-based system the way insulin syringes do. Each pen is pre-set to deliver the full dose in a single injection. There are no dials, no unit markings, no calculations.
The pen clicks as it delivers the medication — you'll hear and feel them. The number of clicks varies slightly by dose strength, but you don't need to count them. When the clicks stop and the grey plunger is visible in the window, the injection is complete.
For those specifically searching for a Mounjaro dosage chart in units: the KwikPen system deliberately removes unit measurement from the equation. It's designed so you can't accidentally give yourself the wrong amount.
How the dosing schedule works
Mounjaro's dosing is built on a principle: start low, go slow.
Weeks 1–4: 2.5 mg This isn't really a treatment dose. Think of it as your body's introduction to tirzepatide. The 2.5 mg dose lets your gut, your appetite signalling, and your digestive system start adapting. Most people notice some appetite changes even at this level, but the primary goal here is tolerability, not weight loss.
Weeks 5–8: 5 mg This is where things typically start to shift. The 5 mg dose is the first level considered therapeutic for weight loss. Appetite suppression becomes more noticeable. Food noise — that relentless background thinking about what to eat next — often quiets down significantly. Many of our patients describe this as the point where they first felt the medication was actually doing something.
Weeks 9 onwards: 7.5 mg, 10 mg, 12.5 mg or 15 mg From here, increases happen in 2.5 mg increments, usually every four weeks. However, not everyone needs to keep going up. Some people find their sweet spot at 7.5 mg. Others need 15 mg. There's no "correct" maintenance dose. The right dose is the one where you're seeing meaningful progress without side effects that affect your quality of life.
When to increase your Mounjaro dose
This is one of the most common questions we get: "When should I go up to the next dose?" The answer depends on several things happening simultaneously.
Your prescriber will typically consider an increase when:
- You've been on your current dose for at least four weeks
- Weight loss has plateaued or slowed significantly
- You're tolerating the current dose well (minimal nausea, no persistent GI issues)
- You haven't yet reached your target weight or a clinically meaningful reduction
Equally important is knowing when not to increase. If you're still losing weight steadily on your current dose, there's genuinely no reason to move up. Higher isn't automatically better. Staying on a lower effective dose often means fewer side effects and a smoother experience overall.
Do you lose more weight on higher doses of Mounjaro?
The clinical data says yes — on average. The SURMOUNT-1 trial showed that participants on 15 mg lost more weight than those on 5 mg over 72 weeks. But averages conceal a lot of individual variation.
Some people respond brilliantly to 5 mg or 7.5 mg and maintain steady weight loss without ever needing to go higher. Others need 10 mg or 12.5 mg to see the same effect. The mechanism involves tirzepatide's dual action on both GIP and GLP-1 receptors — at higher concentrations, receptor activation increases, which can amplify appetite suppression and metabolic effects.
But there's a trade-off. Higher doses also mean a higher probability of gastrointestinal side effects. The goal isn't to reach the maximum dose. It's to find the lowest dose that gives you a meaningful, sustainable result.
Mounjaro dose for weight loss: what the evidence shows
Tirzepatide was originally developed for type 2 diabetes, but its weight loss effects became impossible to ignore during clinical trials. Here's what the headline data looks like across different doses:
| Trial dose | Average body weight reduction | Timeframe |
|---|---|---|
| 5 mg weekly | ~15% | 72 weeks |
| 10 mg weekly | ~19.5% | 72 weeks |
| 15 mg weekly | ~22.5% | 72 weeks |
For context, a 15% reduction in body weight for someone weighing 100 kg means losing 15 kg — roughly 2.4 stone. At the higher end, 22.5% would be 22.5 kg, or about 3.5 stone. These are meaningful, life-changing numbers for many people.
But trial conditions aren't the same as real life. Participants had structured dietary support, regular check-ins, and controlled environments. Real-world results vary. What's consistent, though, is that most people on Mounjaro at therapeutic doses (5 mg and above) see clinically significant weight loss — defined as at least 5% of body weight.
Starting dose for weight loss
The starting dose is always 2.5 mg, regardless of whether you're taking Mounjaro for weight management or blood sugar control. This doesn't change based on your body weight, BMI, or how much you want to lose. Everyone begins at the same place.
This sometimes frustrates people who feel they should be on a higher dose from the start. We understand that. But the 2.5 mg initiation period significantly reduces the risk of severe nausea, vomiting, and diarrhoea that can occur when the body is exposed to GLP-1 and GIP receptor agonists for the first time.
What is the highest dose of Mounjaro?
The maximum licensed dose of Mounjaro is 15 mg per week.
At 15 mg, the dual GIP/GLP-1 receptor activation is at its strongest. For patients who've worked through the lower doses without reaching their treatment goals, 15 mg represents the final escalation step.
Not everyone will reach 15 mg, and that's completely fine. In clinical practice, a significant number of patients find that 10 mg or 12.5 mg delivers the results they need. If you're on 15 mg and still not seeing the progress you'd expect, that's a conversation to have with your prescriber about whether the treatment plan needs adjusting.
What happens when you reach the highest dose?
If you're on 15 mg and you've reached a weight plateau, it doesn't necessarily mean the medication has stopped working. Plateaus are normal in any weight loss process. Your prescriber might suggest:
- Reviewing your dietary habits and activity levels
- Checking for factors that could be interfering (medication interactions, stress, sleep)
- Continuing at 15 mg for longer — some patients see renewed progress after a temporary stall
- Considering combination approaches or alternative treatments if Mounjaro alone isn't sufficient
Managing side effects at each dose level
Side effects are dose-dependent, which is one of the main reasons for the gradual titration schedule. Here's what to expect:
At 2.5 mg: Most people tolerate this well. Mild nausea is the most common complaint, usually in the first week or two. It tends to settle quickly.
At 5 mg: Nausea may return briefly when you step up. Some people notice changes in bowel habits — constipation is more common than diarrhoea at this level. Reduced appetite becomes more pronounced.
At 7.5–10 mg: This is where GI side effects are most commonly reported as bothersome. Nausea, bloating, and acid reflux can occur. Eating smaller meals, avoiding fatty or very rich foods, and eating slowly all help considerably.
At 12.5–15 mg: Some people sail through these doses with minimal issues. Others find that side effects which were manageable at lower doses become more intrusive. If that happens, your prescriber might suggest stepping back down to the previous dose for a period before trying again.
How Mounjaro dosage compares to other treatments
If you're comparing options, here's how Mounjaro's dosing stacks up against other weight loss medications available in the UK:
| Medication | Active ingredient | Dose range | Injection frequency | Mechanism |
|---|---|---|---|---|
| Mounjaro | Tirzepatide | 2.5–15 mg | Once weekly | Dual GIP + GLP-1 |
| Wegovy | Semaglutide | 0.25–2.4 mg | Once weekly | GLP-1 only |
| Saxenda | Liraglutide | 0.6–3.0 mg | Once daily | GLP-1 only |
The numbers aren't directly comparable — 15 mg of tirzepatide and 2.4 mg of semaglutide are very different molecules with different potencies. What matters is the clinical outcome, and head-to-head data suggests Mounjaro's dual-receptor approach generally produces greater average weight loss than GLP-1-only medications.
If you're interested in how the two leading options compare in more detail, we've written a thorough Wegovy vs Mounjaro comparison that covers efficacy, cost, side effects, and availability.
Practical tips for each dosage stage
When you're just starting (2.5 mg): Don't judge the medication by this dose. It's an acclimatisation period. Focus on establishing your injection routine, picking your injection site, and getting comfortable with the KwikPen. If you're unsure about injection technique, our guide on where to inject Mounjaro walks through everything.
When you move to a therapeutic dose (5–7.5 mg): This is when dietary changes start to matter more. Your appetite will likely decrease noticeably — use that as an opportunity to focus on food quality rather than quantity. High-protein meals help maintain muscle mass during weight loss and tend to sit better with the medication than carb-heavy options.
At higher doses (10–15 mg): Stay in regular contact with your prescriber. Higher doses aren't something to manage in isolation. If you're experiencing persistent side effects, a temporary dose reduction can sometimes help your body catch up.
The bottom line
Mounjaro's dosing structure is deliberately gradual. Starting at 2.5 mg and working up in 2.5 mg steps gives your body time to adjust and helps your prescriber identify the right dose for you — which may well be lower than the maximum.
The most important thing isn't which dose you end up on. It's finding the level where you're losing weight at a healthy, sustainable rate with manageable side effects. If you're considering Mounjaro, or you're already on it and have questions about when to increase your dose, speaking with a prescriber who understands your individual situation is always the best next step.
Frequently asked questions
What is the normal starting dose of Mounjaro?
The starting dose is always 2.5 mg once weekly. This applies to everyone regardless of body weight, BMI, or treatment goals. You'll stay on 2.5 mg for a minimum of four weeks before your prescriber considers increasing to 5 mg.
How long do you stay on each Mounjaro dose?
A minimum of four weeks at each dose level. Some people stay on a particular dose for longer — especially if they're losing weight steadily and tolerating it well. There's no maximum time you can remain on a given dose. Your prescriber will review your progress at each check-in.
Can I increase my Mounjaro dose after two weeks?
No. The four-week minimum between dose increases is a clinical requirement, not a suggestion. Increasing earlier significantly raises the risk of severe gastrointestinal side effects. If you're finding your current dose isn't effective after only two weeks, give it the full four weeks — the medication's effects build gradually.
Is 15 mg of Mounjaro the most effective dose?
It's the highest available dose and, on average across clinical trials, produces the greatest weight loss. But "most effective" isn't the same as "best for everyone." If you achieve your goals on 7.5 mg or 10 mg with minimal side effects, that's a better outcome than struggling on 15 mg. Effectiveness is individual.
Do I need to take Mounjaro at the same time every day?
Mounjaro is a once-weekly injection, not daily. You should take it on the same day each week, but the exact time of day doesn't need to be identical. If you need to change your injection day, you can do so as long as there's at least three days between injections.
This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before starting any treatment.