Mounjaro Dosing Guide for UK Patients: Finding The Right Dose For You

Starting Mounjaro, or thinking about changing your dose? If you're not sure what to expect from your treatment, or you want to know when your dose might change, here’s a guide to walk you through, step by step.

Article summary

• Mounjaro (tirzepatide) starts at 2.5mg once a week and can increase in 2.5mg steps, up to a maximum of 15mg. Increases happen no sooner than every 4 weeks, and only if your current dose is well tolerated.
• You don't need to convert mg to ml yourself. Every Mounjaro pen, whatever the strength, delivers a fixed 0.6ml dose. The mg amount depends on which pen your prescriber gives you.
• There's no single "right" dose for everyone. Many people see results on a lower maintenance dose, and there's no pressure to keep increasing your dose.

Mounjaro dosage chart

Starting Mounjaro for weight loss means starting at the lowest dose, measured in milligrams (mg), and building up slowly. This helps your body get used to the medicine and keeps side effects as manageable as possible.

This chart shows the fastest possible pathway through each Mounjaro dose, moving up every 4 weeks. Every dose, at every strength, is given as a 0.6ml injection once a week. [1]

Note: You don't need to remember the 6 different volumes. Every pen strength delivers exactly the same 0.6ml, so the only thing that changes as you move through the chart is which pen you've been prescribed.

Mounjaro dosing schedule

Mounjaro is a once-weekly injection, so you'll give yourself 1 weekly dose on the same day each week. You can take it at any time of day, with or without meals, so it's a good idea to pick a time of day that's easy to remember and stick with it. [1]

A common misconception is that faster is better. Dose increases are not an automatic escalation that happens on a set date, they're a clinical decision. The aim throughout is steady weight loss you can sustain, built around your own experience of the medicine, not a race to 15mg. Many people see results on lower doses. [2]

"There's no need for everyone to reach 15mg. What matters is finding the dose that gives you good results with side effects you can live with, and that's different for everyone.” — MedExpress Clinical Team

You can change your injection day if you need to, as long as at least 3 days have passed since your last dose. [2] This comes from the medicine's official labelling and prescribing guidance. Sticking to your prescribed schedule, known as adherence, is one of the simplest ways to get consistent results. In fact, published MedExpress data shows that sticking to your medication is the largest predictor of weight loss success. [2]

Your dose starts low and goes up in stages, no matter what weight loss treatment you've used before. This gradual step-up process is known as titration or dose escalation. Treatment begins with 2.5mg once a week. After 4 weeks, this usually increases to 5mg, but there’s no pressure to do so if you’re happy with your current dose. From there, your dose can go up in 2.5mg steps, but only after a minimum of 4 weeks on your current dose, and only if you're tolerating it well. [1]

The recommended maintenance doses are 5mg, 10mg and 15mg. The 7.5mg and 12.5mg doses exist to help you move between these levels gradually, but you can use them as maintenance doses, too. [1] Your clinician reviews your response at each dose stage while you work towards your individual maintenance dose rather than a fixed target.

Reaching the highest dose isn't the goal for everyone. A lower maintenance dose can still give you steady, meaningful weight loss while keeping side effects easier to manage. Your injection technique and site matter too, so it's worth getting comfortable with the basics early on.

One more thing worth knowing: if you take the combined oral contraceptive pill, Mounjaro can reduce how well it works. You'll need to use an additional barrier method, such as condoms, for 4 weeks after you start treatment and for 4 weeks after each dose increase. [1,2]

What's the starting dose for Mounjaro?

Everyone starts Mounjaro at the same dose: 2.5mg, administered once a week. This applies even if you've used another weight loss injection before. [1]

The 2.5mg introduction dose is the entry level dose for everyone. Some people will move onto higher doses every 4 weeks if they feel that they are ready to move up. This may be because they want a greater treatment effect, for example, if they aren't seeing the desired improvement in weight or appetite-related symptoms on 2.5 mg. However, others may find that the lower dose works well for them. It is not essential to move up through the different doses, and most people find that side effects tend to be mildest at the lowest dose.

What to expect at each stage

Digestive side effects, including nausea, vomiting, diarrhoea, constipation, acid reflux and bloating, are most common when you start Mounjaro or when you increase your dose. You might also notice tenderness, irritation or other skin reactions where you inject. These symptoms tend to settle down within a few days to a couple of weeks as your body gets used to the new dose.

Staying on top of your hydration can help, especially if you've had vomiting or diarrhoea. Mild, short-lived symptoms like these are generally manageable side effects while your body adjusts, but anything severe or that doesn't settle isn't something you need to learn to live with. Our Mounjaro side effects guide has more detail on what's normal and what to watch for. There are also treatments available that can help keep side effects under control.

A small number of side effects need urgent attention. Call 999 or go to A&E if you get severe, ongoing stomach pain, especially if it spreads to your back or right shoulder, as this could be a sign of pancreatitis or a gallbladder problem. Also call 999 if you have difficulty breathing or swelling of your lips, tongue or throat, as these can be signs of a severe allergic reaction. For all information on side effects, see your patient information leaflet.

Weeks 1–4

You'll start with 2.5mg once a week. As well as being the starting point for Mounjaro, this dose also is when you’ll get into the habit of administering your weekly injection.. Mild nausea or an upset stomach are common at this stage, and they usually pass as your body gets used to the medication.

It's a good time to get to know your injection sites and settle into a routine. This should also make it easier to remember to do your injection every week.

Before each injection, check the liquid in the pen. It should be clear and colourless to slightly yellow in appearance, with no visible particles. If it looks cloudy or discoloured, don't use it and speak to your pharmacist.

Weeks 5–8

If you’re looking to increase your dose, you may be able to move up to 5mg from week 5. Submit a request, and your clinician will determine if increasing your dose is right at this time. However, some people spend longer on lower doses before titrating up, and some never increase at all. The aim is to find a dose that is both effective and that keeps your side effects manageable so that they don’t have a negative impact on your day to day life.

You may notice side effects again around the increase, but they may be milder and shorter-lived than in your first few weeks.

Weeks 9–12

By now you should be fairly settled into a routine with your weight loss medication, and probably starting to see positive effects in terms of your scale weight and maybe even body shape. If you're tolerating your current dose well, you may look to increase it, but again, this is a personal choice and should be based on your individual circumstances.

Sticking to a balanced, reduced-calorie diet and good nutrition alongside your injections can help you get the most from treatment at this stage.

Weeks 13–16

You may have decided to stay on a low dose of Mounjaro, you may still be titrating up, or you may have even reached your weight loss goal and be ready for maintenance dosing. Whatever stage you are at, you may have reached a point where appetite control and weight loss feel most settled.

Weeks 17+

Every weight loss journey is personal, and there is no exact speed or trajectory that it should take. At some point, you’ll be ready to move to a maintenance dose. This is the dose that helps you to maintain your new healthy weight, while also ensuring side effects are manageable. Some people reach the highest dose of Mounjaro before moving onto maintenance dosing, while others find that the treatment continues to work well for them at a much lower dose.

Whatever your maintenance dose is, by this point you should have reached a weight that you are happy with and feel much confident in your health and appearance. Sometimes it may be necessary to alter your dose more than once to find the right one to enable you to maintain your weight. And remember, a healthy, balanced diet and regular physical activity will also go a long way with supporting long-term weight management.

You can read more about what results tend to look like over time.

Mounjaro Dosing FAQs

Who decides when your dose increases?

When you feel ready to move up, you can request the next dose of Mounjaro. Your prescriber will review your treatment, taking into account your weight loss so far and any side effects you are experiencing, before deciding whether it is suitable for you.

When should your dose increase?

The earliest a dose can increase is after 4 weeks on your current dose, and only if that dose is being well tolerated. [1] There's no rule that says you must increase every 4 weeks. Many people stay at a dose for longer, and that's a normal and safe way to use Mounjaro.

What's the maximum dose of Mounjaro?

The maximum dose is 15mg, given once a week. [1] Reaching 15mg isn't necessary for everyone. Some people get excellent results and stop increasing well before this point.

What's a maintenance dose?

A maintenance dose is the dose you settle on for the longer term, once you have found the one that gives you good results with side effects you can manage. The recommended maintenance doses for Mounjaro are 5mg, 10mg and 15mg. [1] However, some people stick at other available doses long term.

How long should you stay on each Mounjaro dose, and is this the same for everybody?

The minimum time on any dose is 4 weeks, but this is only the earliest point at which an increase can be considered, not a deadline. [1] How long you stay depends on your individual response and tolerability, so your experience may be quite different from someone else's on the same dose. Your clinical team will review your progress, using clinical guidance rather than a fixed timetable.

How do I convert ml to mg?

You don't need to. Every Mounjaro dose, whatever the pen strength, is delivered in the same 0.6ml amount. [1] It's the pen you've been prescribed, not the volume you inject, that sets your mg dose. As a quick reference:

• 2.5mg = 0.6ml
• 5mg = 0.6ml
• 7.5mg = 0.6ml
• 10mg = 0.6ml
• 12.5mg = 0.6ml
• 15mg = 0.6ml

What should I do if I miss a dose?

The missed-dose rule is simple. If it's been 4 days or less since your missed dose, that's your window to give yourself the injection as soon as you remember. If it's been more than 4 days, skip that dose completely and take your next one on your usual day. [3] Never give yourself 2 injections close together to make up for a missed one. [2] After a missed dose, just carry on with your regular weekly schedule.

Is it possible to split my Mounjaro dose?

Mounjaro pens are designed to deliver one full, fixed dose per injection, and splitting a dose isn't something MedExpress recommends or supports. Everyone's tolerance for side effects is different, so if you're finding a dose difficult, the safer option is to speak to your clinical team. You may need to stay at your current dose for longer, or step back to a previous one. However, this should only be done under proper medical supervision.

What should I do if I can't tolerate my new dose?

Contact your clinical team. They may suggest staying at your current dose for longer before trying again, or going back to your previous dose for a while. Mild nausea, diarrhoea or constipation are common and often settle on their own, and our side effects guide has practical tips for managing them. But if you get severe, ongoing stomach pain, or difficulty breathing or swelling of your lips, tongue or throat, treat this as an emergency and call 999 or go to A&E. If you think you've used more Mounjaro than you should have, call NHS 111 for advice rather than waiting to see how you feel. [3]

At MedExpress, we offer online consultations with regular clinical check-ins, and a range of weight loss treatments including Mounjaro, Wegovy Pen, Wegovy Pill and Foundayo, and our team can help you find the right treatment for you.

References

1. Eli Lilly and Company Limited. Mounjaro KwikPen 2.5 mg solution for injection in pre-filled pen: Summary of Product Characteristics (SmPC) [Internet]. electronic medicines compendium (emc). Updated 2026 Sep 8 [cited 2026 Sep 21]. Available from: https://www.medicines.org.uk/emc/product/15481/smpc
2. Rosenior‐Patten O, Lees Z, Rowe R, Hussain S, Ahmad E, Brooke E, et al. Real‐World Effectiveness and Treatment Patterns of Tirzepatide in a Large UK Digital Health Cohort. Diabetes, Obesity and Metabolism. 2026 Aug 6;.https://pubmed.ncbi.nlm.nih.gov/42560020/
3. NHS. Tirzepatide: a medicine to manage type 2 diabetes and treat obesity [Internet]. nhs.uk. Reviewed 2026 May 15 [cited 2026 Sep 21]. Available from: https://www.nhs.uk/medicines/tirzepatide/