Starting the Mounjaro 5mg Bundle: What Actually Happens Next

You've just finished your first pen and your prescriber has moved you up

A month ago you injected your first 2.5mg dose and, if things went to plan, not very much happened, which was the point. The starter pen is about getting your digestive system used to tirzepatide, not about dramatic results. If you want to revisit how that opening phase works, the guide to the 2.5mg starting dose covers what to expect in that first month. Now your prescriber has given the go-ahead for 5mg, and the question most people have at this stage is: will the side effects be worse?

Broadly, GI symptoms (nausea, loose stools, constipation, reflux, burping) can return or intensify when you step up. They are usually most noticeable in the first few days after the new dose, then settle. The NHS medicines page for tirzepatide on the NHS lists the full side-effect profile and is worth a read before you inject for the first time at the new strength. Injection-site reactions, fatigue and headache are also reported, though less commonly.

A simple habit worth building: after each injection, note the date and any symptoms in your phone's notes app. Takes under a minute, and it gives your prescriber something concrete to work from at your next review rather than a vague "felt a bit rough for a bit."

If you experience severe, persistent stomach pain that spreads to your back, get urgent medical help and do not wait for a routine review. Acute pancreatitis is a known but infrequent risk with GLP-1 medicines, and speed matters.

What the 5mg pen is and is not doing for your weight

At 5mg you are in genuinely therapeutic territory. Some people notice appetite changes as early as the first or second injection at this dose; others take longer. Results vary because weight is shaped by biology as much as behaviour, the medicine works with your physiology, not instead of it.

The headline trial figures (around 20–21% average body-weight reduction in SURMOUNT-1 at 15mg) come from participants who titrated all the way up over many months. Arriving at 5mg is not the end of the schedule for most people; it is, depending on how you tolerate it, a stepping stone. The 15mg pen sits at the top of the licensed range and is where the most substantial trial data sits, but getting there is a clinical decision taken one step at a time.

NICE reviewed tirzepatide's evidence base as part of TA1026, published in December 2024, that appraisal covers adults with BMI ≥35 plus at least one weight-related condition (thresholds adjusted for some ethnic backgrounds), which is the NHS commissioning frame. Private eligibility, per the licensed prescribing criteria, extends to BMI ≥30, or from 27 with a qualifying condition such as high blood pressure, type 2 diabetes or obstructive sleep apnoea. BMI alone does not decide approval; your prescriber reads the whole picture.

If you want a broader look at where 5mg sits across the full dose range, the guide to the 5mg dose covers the clinical detail in more depth.

Storage, supply and what to check before your pen arrives

Mounjaro pens are refrigerated medicines, 2°C to 8°C, away from the freezer compartment. Once you have removed a pen from the fridge, there is a limited window during which it can be kept at room temperature before use. The exact duration is in the Patient Information Leaflet inside the box; the Mounjaro SmPC on the eMC carries the same information in full and is the authoritative source. Do not rely on memory or social media for storage timing.

Rotate your injection site each week, abdomen, thigh and upper arm are all licensed sites. Reusing the same spot repeatedly can cause skin changes that affect absorption.

On the question of cost: private treatment pricing varies by dose and provider, and if you are weighing up your options it helps to understand how Mounjaro is prescribed and supplied as a complete treatment pathway. The 2.5mg and 5mg starter bundle is often how people begin their journey before moving to single-dose pens, and the 5mg pen page sets out what is included at this stage of treatment. For a clear picture of what treatment costs and what is included, the treatment overview page sets out current pricing without the small print.

One thing worth knowing: at nume, every repeat prescription goes through a fresh clinical review. Your next pen is not issued automatically, a real prescriber checks your progress, not a system clock. If you want to understand how the overall process works before committing, the FAQs cover the most common questions, and our clinical approach explains why we do it this way.

If you are ready to check whether you are a candidate for treatment, or if you are already a patient and want to discuss moving to 5mg, a free consultation is the right next step. Our prescribers review it the same day, and if treatment is clinically suitable, dispatch goes out the same working day by DPD.