Anyone starting Mounjaro (tirzepatide) quickly discovers that the medicine is not a single dose but a ladder. You start low, climb in fixed steps, and settle at a maintenance level that balances weight-loss results against side effects. The ladder exists for good reason, yet it is one of the most misunderstood aspects of treatment. People wonder why they are “only” on 2.5 mg when they feel fine, why a friend is on 15 mg while they are on 7.5 mg, or whether they can skip a rung to speed things up.
This guide explains the schedule as it appears in the UK licence, what is happening at each level, how prescribers decide when to move up, and what to do when doses are missed or side effects bite.
The six strengths
Mounjaro is supplied in the UK as a multi-dose KwikPen containing four weekly doses. There are six pen strengths:
- 2.5 mg
- 5 mg
- 7.5 mg
- 10 mg
- 12.5 mg
- 15 mg
Each pen delivers one fixed strength; you do not adjust the dose on the pen itself. Moving up means switching to a new pen. The injection is given once a week, on the same day each week, under the skin of the abdomen, thigh or upper arm, at any time of day and with or without food.
The standard titration schedule
The licensed starting dose is 2.5 mg once weekly for four weeks. This is explicitly a starting dose for tolerability, not a treatment dose; it is there to let the digestive system adapt before the medicine reaches levels that drive meaningful weight loss.
After four weeks the dose is increased to 5 mg once weekly. From here, the dose can be increased in 2.5 mg increments after a minimum of four weeks on the current dose, as far as a maximum of 15 mg once weekly.
Laid out, the fastest possible path is:
- Weeks 1 to 4: 2.5 mg
- Weeks 5 to 8: 5 mg
- Weeks 9 to 12: 7.5 mg
- Weeks 13 to 16: 10 mg
- Weeks 17 to 20: 12.5 mg
- Week 21 onwards: 15 mg
That is roughly five months to reach the top dose. Many people never go that far, and there is nothing wrong with that.
Why the steps are four weeks long
Tirzepatide has a half-life of about five days, which means it takes around four weeks of weekly dosing for blood levels to reach a steady state at any given strength. Assessing tolerability before that point is premature: side effects that appear in week one of a new dose often fade by week three. Increasing again too early stacks a new rise on top of an unsettled baseline and is the most common cause of severe nausea and vomiting.
The four-week minimum is therefore a floor, not a target. There is no clinical reason not to stay at a dose for eight or twelve weeks if that is where you feel well and the weight is moving.
What “maintenance dose” means
The licence describes 5 mg, 10 mg and 15 mg as maintenance doses, with 7.5 mg and 12.5 mg as intermediate steps. In practice, any dose from 5 mg upwards can be a maintenance dose if it is working. The clinical trials that supported the weight-management licence (the SURMOUNT programme) tested 5 mg, 10 mg and 15 mg and found that all three produced substantial weight loss, with higher doses producing more on average but also more gastrointestinal side effects.
The right maintenance dose is the lowest one that gives you a good rate of weight loss with side effects you can live with. That is different for everyone and it is a discussion to have with your prescriber every time you consider moving up.
How a prescriber decides whether to increase
A good review at the end of each four-week block looks at:
- Tolerability. Are nausea, reflux, constipation or diarrhoea manageable? Are they improving or worsening?
- Weight change. A loss of around 0.5 to 1 kg a week is typical once above the starting dose. If weight is still moving well, there may be no need to increase.
- Appetite control. If hunger has returned and weight loss has stalled for a few weeks, an increase is more likely to help.
- Hydration and nutrition. Signs of dehydration or very low food intake are a reason to hold or step back, not to increase.
- Other medicines. Anyone on insulin or a sulfonylurea needs blood-glucose monitoring and possible dose reductions of those medicines as tirzepatide increases.
Registered online pharmacies are expected to repeat a short consultation before supplying a higher strength for exactly this reason. It is not a sales hurdle; it is the point at which someone qualified decides that the next rung is safe for you.
Stepping down
The schedule is not one-way. If a dose increase brings side effects that do not settle within a few weeks, prescribers commonly drop back to the previous strength for another month before trying again. Some people find that 7.5 mg or 10 mg is their ceiling and stay there long-term. Reducing dose is not a failure; it is part of how the medicine is meant to be used.
Missed doses
The rule in the UK product information is simple: if you miss a dose and it is within four days (96 hours) of when it was due, take it as soon as possible and then carry on with your usual day. If more than four days have passed, skip the missed dose entirely and take the next one on the normal day. Never take two doses within three days of each other.
If you have missed two or more consecutive doses, particularly on the higher strengths, speak to your prescriber before restarting. Tolerance to the gastrointestinal effects fades after a few weeks off, and restarting at 12.5 mg or 15 mg after a gap can cause the side effects you experienced at the start of treatment to return. It is often safer to restart one or two steps lower.
Changing your injection day
You can move your weekly injection day as long as there are at least three days (72 hours) between the last dose and the new one. If you want to move from Monday to Saturday, for example, you could inject on Monday, then again on Saturday of the same week, and continue every Saturday thereafter.
Common questions about dose
I feel no different on 2.5 mg. Is it working?
Some people notice reduced appetite even at 2.5 mg; many do not. This is expected. The starting dose is about preparing your body, not delivering the full effect.
Can I stay on 2.5 mg?
The licence positions 2.5 mg as an initiation dose only. If you are losing weight on it and have no wish to increase, discuss it with your prescriber; some will support staying there for a period, but it is not a licensed maintenance dose.
Is 15 mg always better?
On average it produces the greatest weight loss, but averages hide a lot of variation. Plenty of people achieve excellent results at 5 mg or 7.5 mg with far fewer side effects. More is not automatically better.
Can I split a higher-strength pen to make a lower dose?
No. KwikPens are fixed-dose devices and are not designed to be partially dosed. Attempting to do so gives an unknown dose and is unsafe.
Does the schedule differ for type 2 diabetes?
The titration is the same, but the target dose is guided by blood-glucose control rather than weight alone, and it usually involves the GP or diabetes team because other diabetes medicines may need adjusting.
Getting the right pen at the right time
Because each strength is a separate pen and each step needs a prescriber’s sign-off, the supply chain has to keep pace with the schedule. This is one of the practical advantages of buying from a registered UK pharmacy that stocks all six strengths. You can obtain a Mounjaro KwikPen from a GPhC-registered UK pharmacy such as Cured Pharmacy, which lists every strength from 2.5 mg to 15 mg and requires an online clinical consultation before supply, with a review before each increase.
Whichever pharmacy you use, plan ahead: order the next pen a week or so before your current one runs out so that a delivery delay does not become a missed dose. Keep unused pens in the fridge, and note the date you first use each one; a pen in use can be kept at room temperature for up to 21 days.
Storing and handling the pen through the schedule
- Store unopened pens at 2 to 8 °C. Do not freeze; a frozen pen must be discarded.
- Once in use, a pen may be kept below 30 °C for up to 21 days.
- Use a new needle for every injection and dispose of it in a sharps bin.
- Rotate injection sites to avoid lumps or irritation.
- Check the liquid is clear and colourless before each injection.
Summary
Mounjaro’s dosing schedule is a deliberate, gradual climb: four weeks at 2.5 mg to adapt, then steps of 2.5 mg no more often than every four weeks, stopping wherever results and tolerability meet. Missed doses have a four-day catch-up window, injection days can be moved with a three-day gap, and stepping down is a normal part of finding the right level. Every increase should be a clinical decision, made with a prescriber who knows how you have tolerated the current dose, and Cured Pharmacy builds that review into the ordering process for each strength.
This article is for general information and is not a substitute for advice from your prescriber or pharmacist. Mounjaro is a prescription-only medicine; dosing decisions should always be made with a registered healthcare professional.
