The maximum licensed dose of Mounjaro (tirzepatide) for weight loss is 15mg once a week, given as a self-injection. You do not start here: everyone begins on the 2.5mg starter dose and steps up gradually, only reaching 15mg if a prescriber judges it clinically appropriate.
Mounjaro is a prescription-only medicine. A dose is only prescribed and increased after a clinical consultation with a GPhC-registered prescriber, and the maximum dose is not right or necessary for everyone. This article explains the full dose ladder, why increases are gradual, and what the maximum dose means in practice.
What is the maximum dose of Mounjaro for weight loss?
The maximum licensed dose of Mounjaro (tirzepatide) is 15mg once weekly. Mounjaro works by activating two gut-hormone receptors at once — GLP-1 and GIP — which helps reduce appetite and control hunger.
The 15mg dose is the highest strength available and is reached only after working up through the lower doses over several months. Many people achieve their goals on a lower maintenance dose and never need the maximum. You can read more on the Mounjaro treatment page.
What are all the Mounjaro doses in order?
Mounjaro is taken as a once-weekly injection, and the dose is increased in steps. The licensed titration ladder runs from the 2.5mg starter dose up to the 15mg maximum.
| Dose (weekly) | Role | Price per month |
|---|---|---|
| 2.5mg | Starter dose (not for weight loss on its own) | £160 |
| 5mg | First maintenance step | £185 |
| 7.5mg | Titration step | £240 |
| 10mg | Titration step | £260 |
| 12.5mg | Titration step | £275 |
| 15mg | Maximum licensed dose | £295 |
These prices are listed as plain facts and include the medicine. The lowest-cost dose is £160 per month. Your prescriber decides the right dose for you based on how you respond and tolerate the medicine.
Why does Mounjaro start low and increase gradually?
Mounjaro starts at 2.5mg and increases gradually to help your body adjust and to reduce side effects. The 2.5mg starter dose is a run-in step designed to settle the digestive system — it is not considered a treatment dose for weight loss on its own.
Stepping up slowly lowers the chance of nausea, vomiting, diarrhoea and constipation, which are the most common side effects and tend to be strongest when a dose first increases. Typically each dose is maintained for around four weeks before any increase, and a prescriber reviews how you are getting on before moving you up.
Does everyone reach the 15mg maximum dose?
No — many people do not reach the 15mg maximum dose of Mounjaro, and they do not need to. The right dose is the lowest one that gives you a good result with tolerable side effects, which is a clinical judgement made with your prescriber.
Some people settle on 5mg or 10mg as their long-term maintenance dose. Others step up further. The decision depends on your weight-loss progress, how well you tolerate the medicine, and your overall health — not on a fixed target for everyone.
How effective is the 15mg dose?
In the SURMOUNT-1 trial, participants on the 15mg dose lost on average 22.5% of body weight over 72 weeks, alongside lifestyle support. Individual results vary; not everyone reaches this.
This figure comes from a clinical trial at the maximum dose combined with diet and activity changes. It is an average across many participants, not a guarantee, and real-world results differ from person to person. Citation: Jastreboff AM, et al. N Engl J Med. 2022;387(3):205–216.
What are the side effects to be aware of?
The most common side effects of Mounjaro (affecting more than 1 in 10 people) are nausea, diarrhoea, constipation, vomiting, decreased appetite and fatigue. These are usually most noticeable when starting or after a dose increase, and often ease as your body adjusts.
Rare but serious risks include severe allergic reaction, acute pancreatitis, severe hypoglycaemia (low blood sugar), severe gastrointestinal disease, and worsening diabetic retinopathy. Seek urgent medical advice if you experience severe or persistent symptoms. You can report suspected side effects to the MHRA via the Yellow Card scheme at https://yellowcard.mhra.gov.uk/.
Who can be prescribed Mounjaro?
Mounjaro may be prescribed for weight management in UK adults aged 18 or over with a BMI of 30 or more, or a BMI of 27 or more alongside a weight-related condition such as type 2 diabetes, high blood pressure or sleep apnoea.
It is not suitable if you are pregnant, planning pregnancy or breastfeeding; have type 1 diabetes; have a personal or family history of medullary thyroid carcinoma or MEN2; have a history of pancreatitis; have severe gastrointestinal disease; have an active eating disorder; have severe liver or kidney impairment; or are allergic to the active ingredient. A free online consultation checks whether treatment is clinically appropriate for you.
How does Mounjaro compare with other options?
Mounjaro (tirzepatide) activates two gut-hormone receptors — GLP-1 and GIP — while other weight-loss medicines we offer work on the GLP-1 receptor alone. The right choice depends on your health, preferences and prescriber assessment, not a one-size-fits-all rule.
- Wegovy injection (semaglutide) — a once-weekly GLP-1 injection.
- Wegovy Tablet (oral semaglutide) — a once-daily tablet taken on an empty stomach.
- Foundayo (orforglipron) — a once-daily small-molecule GLP-1 tablet taken at any time of day, with or without food.
You can see everything side by side on our treatments overview or the combined weight-loss injections page.
This article is for information only and is not a substitute for personalised medical advice. Weight-loss medicines are prescription-only, are not suitable for everyone, and are prescribed only after a clinical consultation with a GPhC-registered prescriber. Individual results vary. Always speak to a UK-registered pharmacist or doctor before starting or changing any prescription medication.
