Mounjaro dose steps: when you move up, and what changes

Mounjaro dose steps follow one simple shape: 2.5mg once weekly for four weeks, then 5mg, and after that increases of 2.5mg at a time — 7.5mg, 10mg, 12.5mg — with at least four weeks at each step, up to a maximum of 15mg. What changes at each step is the amount of medicine, not the injection itself, and the reason the climb is slow is to reduce side effects. Only a prescriber decides if and when you move up.

That is the licensed schedule for Mounjaro in the UK, where tirzepatide is MHRA-licensed for weight management and recommended by NICE (TA1026, December 2024). This page is information only, not medical advice and not encouragement to use any medicine: the patient information leaflet in your own pack, your prescriber and your pharmacist come first.

The Mounjaro dose ladder, step by step

Mounjaro is started low and increased slowly, specifically to reduce side effects. In order:

• 2.5mg once weekly for 4 weeks. A starter dose, not a treatment dose — its job is to let the body get used to the medicine.
• 5mg once weekly. The first of the maintenance doses.
• Then 2.5mg at a time, if needed. 7.5mg, then 10mg, then 12.5mg — each after at least 4 weeks on the dose before it.
• 15mg once weekly. The maximum dose. Nothing goes above it.

Everything else about the injection stays the same as you climb: once a week, on the same day each week, under the skin of the tummy or thigh — or the back of the upper arm if someone else gives it — at any time of day, with or without food, rotating the site. Our guide to injection sites covers the rotation, and our dosage page sets out the six pen strengths in full.

Why 2.5mg is a starter dose, not a treatment dose

This is the single most misunderstood rung on the ladder. The 2.5mg pen exists to introduce the medicine gently over four weeks; it is not one of the doses treatment is designed to settle on. Tirzepatide acts on two gut hormone receptors at once, GIP and GLP-1, reducing appetite and "food noise", helping you feel full sooner and for longer, and slowing how quickly the stomach empties. Four weeks at a low dose gives your digestion time to meet all of that before the dose rises.

So if the first month feels underwhelming, that is not a verdict on the medicine. It is also why nobody should judge Mounjaro on four weeks at 2.5mg, and why a prescriber will usually be looking at the step to 5mg rather than at your weight at week three.

What "at least four weeks" actually means

Four weeks is a floor, not a schedule you are behind on. The rule is that increases come no more often than every four weeks — which means a prescriber can quite properly keep you on a dose for longer if side effects are hard going, or if the dose you are on is doing the job. Any change to your dose, in either direction, is their decision rather than a fixed rule.

What it never means is going up faster. If a dose was late or missed around the time of a planned increase, our guide on missed doses covers what the leaflet says — and if you have missed more than one, speak to your prescriber before the next injection rather than assuming the step still stands.

Which doses are maintenance doses

Three of the six strengths are maintenance doses: 5mg, 10mg and 15mg. The maintenance dose is tailored to you. The other two strengths above the starter dose — 7.5mg and 12.5mg — are titration steps, the rungs between maintenance levels rather than destinations in their own right.

That matters for how you read your own prescription. Being on 7.5mg usually means you are between levels; being on 5mg does not mean you are only part-way through something. In the SURMOUNT-1 trial, average weight loss over 72 weeks was 16.0% at 5mg, 21.4% at 10mg and 22.5% at 15mg, against 2.4% on placebo — higher doses did more on average, but 5mg was never a token dose, and averages say nothing about what any one person will experience.

Why side effects often cluster after a step up

The whole reason the ladder exists is that side effects are the price of raising the dose too quickly — the schedule is deliberately slow to reduce them. A step up is therefore the moment your body meets a higher dose for the first time, which is exactly when people most often notice something.

The common side effects are nausea, diarrhoea, constipation, vomiting and tiredness. The UK label does not promise how long any of them last after an increase, so nobody honest can give you a number; what your own leaflet says, and what your pharmacist tells you, is the right guide. Worth knowing as you climb:

• Report it before the next step, not after. If a dose is rough, that is information your prescriber needs while there is still a decision to make about the next increase.
• Keep fluids up. Vomiting, feeling sick or diarrhoea can cause dehydration, which can put strain on the kidneys.
• Know the red flags. Pancreatitis is rare but serious, and gallstones can occur; severe stomach pain that will not go away needs urgent medical help. Our side effects page goes through these properly.
• Tell your prescriber about other medicines. Low blood sugar is a particular risk for anyone also using insulin or a sulfonylurea.
• Check the leaflet's note on oral contraception. The leaflet in your pack sets out what to do around a dose increase if you take the contraceptive pill — it is worth re-reading at every step, and your pharmacist will talk it through if anything is unclear.

What to expect in the weeks after starting or stepping up

Reduced appetite is often noticed within the first days to two weeks of treatment. Measurable weight loss usually begins around weeks 4 to 8, then builds over the following months — which is to say it is a slow, cumulative process rather than something that turns on at a particular strength.

The label does not set out a separate timeline for each individual step, so treat week-by-week comparisons between doses with some suspicion. What the medicine is doing is easier to see across a couple of months than across the fortnight after a new pen.

The six-month review point NICE describes

There is one formal checkpoint worth knowing about before you get to it. NICE advises reassessing if less than 5% of starting weight is lost 6 months after reaching the highest tolerated dose.

Read that carefully, because two details do a lot of work. The clock starts when you reach your highest tolerated dose — not when you started treatment, and not necessarily at 15mg, since the highest dose you tolerate may well be 5mg or 10mg. And "reassess" means a prescriber reviews whether the medicine is doing enough to be worth continuing, in the round, alongside diet and physical activity. It is a conversation, not an automatic stop.

On the NHS in England, access follows TA1026's phased rollout; privately, the thresholds are a BMI of 30 or more, or 27 or more with a weight-related condition. Our FAQ covers UK access in more detail.

Staying on a lower dose that works is a real outcome

It is easy to absorb the idea that treatment is a climb to 15mg and anything less is unfinished. It is not. 15mg is the maximum the licence allows, and 5mg and 10mg are maintenance doses in their own right — the dose is meant to be tailored to the person, not raised until the pens run out of numbers.

Someone who is losing weight steadily, tolerating the injection well and comfortable with their routine has a perfectly good reason to stay where they are. Someone whose side effects bite at a higher dose has a perfectly good reason to raise it with their prescriber. Both are ordinary results, and both are decisions to make with a prescriber rather than alone.

New to the injection? Our first-time injection guide walks through the pen step by step, and our using and storing the pen page covers the fridge and in-use rules.

Frequently asked questions

Related reading

• Mounjaro first week: what to expect on the 2.5 mg starter dose
• Missed a Mounjaro dose? What to do, and the 4-day rule
• How to inject Mounjaro the first time: a calm step-by-step