Mounjaro (tirzepatide) is taken once weekly, and the dose is usually increased gradually to improve tolerance (especially nausea and other stomach side effects). The UK dosing schedule follows a simple rule:

Start low (2.5mg weekly),
increase after 4 weeks,
then (if needed) increase by 2.5mg steps, staying on each dose for at least 4 weeks.

This guide explains the full titration ladder (2.5mg → 15mg), how to plan it week-by-week, and the key rules for missed doses and changing your injection day.

If you need the main hub first, use Mounjaro weight loss injection pen:

Table of Contents

Quick summary (the official UK titration rule)

From the UK SmPC and patient leaflet:

Starting dose: 2.5mg once weekly
After 4 weeks: increase to 5mg once weekly
If needed: increase by 2.5mg increments, after a minimum of 4 weeks on the current dose
Maximum dose: 15mg once weekly

The weekly dose ladder (2.5mg → 15mg)

Standard titration schedule (most common pattern)

Weeks	Weekly dose	What this dose is for
Weeks 1–4	2.5mg	Starter dose to help your body adjust
Weeks 5–8	5mg	First treatment dose after starter phase
Weeks 9–12 (if needed)	7.5mg	Optional step-up if clinically needed
Weeks 13–16 (if needed)	10mg	One of the recommended maintenance doses
Weeks 17–20 (if needed)	12.5mg	Optional step-up if clinically needed
Week 21 onward (if needed)	15mg	Max dose + recommended maintenance option

Key rule: you stay on each dose for at least 4 weeks before moving up.

Starter dose vs maintenance dose (what “most people stay on”)

The starter dose (2.5mg)

2.5mg is the starting dose for the first 4 weeks. It’s there to help tolerance before you move to a higher dose.

Recommended maintenance doses

The UK SmPC lists recommended maintenance doses as:

5mg, 10mg, and 15mg.

That doesn’t mean everyone must reach 15mg. In real prescribing, the “right” maintenance dose is the dose that balances:

weight loss benefit,
side effects,
medical conditions and other medicines.

If you have medical conditions that change risk (kidney disease, severe GI issues, insulin use, etc.), review Mounjaro and Medical Conditions: When You Need Extra Caution:

When should you increase the dose?

The official “minimum time” rule

Dose increases (if needed) are done in 2.5mg steps, and only after at least 4 weeks on the current dose.

Practical rule (what clinicians do)

Most prescribers follow this logic:

If you’re tolerating your current dose and weight loss response needs improvement → consider increasing.
If side effects are significant → stay on the same dose longer (don’t rush upward).
If side effects are severe or you get red flags → stop and seek clinical advice (see the red-flag guide below).

For MedCare’s screening and how they decide dose suitability, see:
Online Weight Loss Consultation: What MedCare Asks & Why

How to pick your injection day (and keep it consistent)

The SmPC and patient leaflet both confirm:

You inject once weekly,
at any time of day,
with or without meals.

Best practice: choose one consistent day (e.g., every Monday) and build a simple reminder system.

Rules box: missed dose + changing injection day (UK rules)

If you miss a dose

If it has been 4 days or less since you should have injected, take the missed dose as soon as you remember.
If it has been more than 4 days, skip the missed dose and take the next dose on your regular day.

Never double dose to make up for a missed injection.

If you want to change your weekly injection day

You can change the day as long as there are at least 3 days between two doses.

Where to inject (and how to rotate sites)

Mounjaro is injected under the skin (subcutaneous) into:

abdomen (stomach),
thigh,
or upper arm.

Rotate injection sites with each dose (and if you also inject insulin, use a different injection site).

The “6-month checkpoint” (important for weight management plans)

For weight management, the UK SmPC includes a clear review concept:
If a patient hasn’t lost at least 5% of initial body weight 6 months after titrating to the highest tolerated dose, a decision is needed on whether to continue, based on individual benefit/risk.

This is one reason the dosing schedule matters: you don’t just escalate blindly; you build toward a dose you can tolerate, then evaluate response properly.

Safety note: dose schedule is not the same as suitability

Even if you understand the titration schedule perfectly, you should not start or increase doses without clinical review if you have:

pregnancy possibility / breastfeeding,
history of pancreatitis,
severe digestion disorders,
insulin or sulfonylurea use (higher hypoglycaemia risk),
severe kidney or liver disease,
surgery/anaesthesia planned soon.

Use this safety page to pre-check red flags:
Who should NOT use Mounjaro? (Contraindications + Red Flags)

FAQs

Is 2.5mg a “real dose” or just a starter?

It’s the official starting dose for once-weekly use for 4 weeks, then you increase to 5mg.

Do I have to reach 15mg?

No. 15mg is the maximum dose, and maintenance doses commonly used are 5mg, 10mg, or 15mg. Your clinician chooses based on response and tolerance.

Can I increase faster than every 4 weeks?

UK guidance says dose increases (if needed) are done after a minimum of 4 weeks on the current dose.

What if I forget my injection?

If it’s within 4 days, take it as soon as possible; if more than 4 days, skip and take the next dose on your normal day.

Can I switch my injection day?

Yes only if there are at least 3 days between doses.