Short answer: According to the product information, Mounjaro (tirzepatide) starts at 2.5 mg once a week for 4 weeks, then goes to 5 mg. If needed, the dose can go up in 2.5 mg steps after at least 4 weeks on the current dose, to a maximum of 15 mg a week. Your GP or prescriber decides which dose you stay on.

Key takeaways

  • Mounjaro has six dose steps: 2.5, 5, 7.5, 10, 12.5 and 15 mg, all once a week.
  • 2.5 mg is a starting dose, not a weight-loss dose: its job is to get your body used to the medicine.
  • The product information lists 5, 10 and 15 mg as maintenance doses.
  • You stay on each step for at least 4 weeks; whether you move up is your prescriber's decision.
  • Your dose is the one printed on your pen; do not split it or increase it on your own.

Mounjaro does not have one fixed dose. Treatment starts low and is raised step by step under medical supervision. This gradual increase is called titration. Its purpose is not to speed up the effect but to reduce digestive side effects such as nausea.

This page is for general information only and does not replace medical advice. Which dose you use and when it changes are decisions for your GP or prescriber alone.

Mounjaro dose chart

Step Weekly dose Role in the product information
1 2.5 mg Starting dose, first 4 weeks
2 5 mg First maintenance dose
3 7.5 mg In-between step
4 10 mg Maintenance dose
5 12.5 mg In-between step
6 15 mg Maximum dose

There are at least 4 weeks between steps, so going from 2.5 mg to 15 mg takes about 20 weeks at the earliest. Not everyone needs the maximum dose, and many people stay on a lower step.

Why start at 2.5 mg?

Tirzepatide slows how quickly the stomach empties and keeps you feeling full for longer. Starting on a high dose would make nausea, vomiting and diarrhoea much more likely. The 2.5 mg dose lets your body adjust; the product information does not list it as a maintenance dose for weight management.

So it is normal not to see much change on the scales in the first four weeks. More on this in when do weight-loss injections start working.

When does the dose go up?

According to the product information, the dose can be raised by 2.5 mg after at least 4 weeks on the current dose. Your prescriber decides whether to do that, looking at how your weight is changing, any side effects and your general health. If a step is hard to tolerate, staying on it for longer is also an option.

Nausea and other digestive side effects can return for a few days after each increase. Why that happens is explained in what happens when your weight-loss injection dose goes up.

What does the "mg" on the pen mean?

The number on the KwikPen label is the weekly dose that pen gives. Each KwikPen holds several doses of the same strength. When your dose changes, you are usually prescribed a pen of the new strength.

Taking a different amount from a pen by splitting doses or counting clicks is not a use described in the product information. Talk to your prescriber about any change to your dose.

Keeping track of your step

Noting how many weeks you have been on each step and how you felt after each increase makes it easier to answer your prescriber's questions at a review. Haftra keeps your dose, injection day and symptoms together. It does not suggest doses or work out dose steps. It is free.

iPhone, iPad and Apple Watch. Free.

Frequently asked questions

What is the starting dose of Mounjaro?

According to the product information, 2.5 mg once a week for 4 weeks, then 5 mg.

What is the highest dose of Mounjaro?

The maximum dose is 15 mg once a week.

Do you lose weight on Mounjaro 2.5 mg?

2.5 mg is a starting dose to get your body used to the medicine, and the product information does not list it as a maintenance dose for weight management. Any change on this step may be small.

Do you have to go up a Mounjaro dose every month?

No. At least 4 weeks on each step is a minimum, not a fixed timetable. Your prescriber decides whether and when you move up, and many people stay below 15 mg.

When is Mounjaro 7.5 mg used?

7.5 mg is the in-between step from 5 mg to 10 mg. After at least 4 weeks on 5 mg, your prescriber may move you to it if needed.

Sources

  • EMA: Mounjaro (tirzepatide), summary of product characteristics
  • MHRA (Medicines and Healthcare products Regulatory Agency)
  • NHS: Obesity treatment

Last reviewed: 26 September 2026