Trying to get 5mg from a 7.5mg Mounjaro pen? Here is what actually happens

Step 1: Understand what the 7.5mg pen is and is not designed to do

Mounjaro's KwikPen is a pre-filled, fixed-dose device. Each strength (2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg) delivers that exact amount per injection, and the pen mechanism does not allow partial doses. So the short answer to whether you can extract 5mg from a 7.5mg pen is: no. The pen is not adjustable, and attempting to interfere with it would compromise sterility and accuracy alike.

Tirzepatide's dosing ladder exists because the early weeks of treatment are about tolerability as much as anything else, the body adjusts gradually, which is why the schedule typically moves in 4-week increments under prescriber supervision. The 7.5mg pen is the third rung of that ladder; if it feels like a step too far, that is a clinical signal worth raising with your prescriber. The Mounjaro treatment overview explains how the titration schedule works and why each stage matters.

If you were recently on 5mg and are wondering how the move to 7.5mg felt for others, the transition from a 5mg to 7.5mg pen is covered in detail, including what side effects tend to surface at that step and why they usually settle. Some patients also find it helpful to read about getting 2.5mg out of a 5mg Mounjaro pen, which explains why splitting doses from a fixed-dose device is not straightforward at any strength, and similarly, how the 5mg pen is constructed makes clear why partial extraction is not a safe or reliable option. For those earlier in the titration who have wondered about getting 5mg out of a 7.5mg Mounjaro pen, the same principle applies, the device simply is not designed to deliver anything other than its labelled dose.

Step 2: Talk to your prescriber before touching anything

In the UK, Mounjaro is a Prescription-Only Medicine regulated under the Human Medicines Regulations 2012. The dose on your prescription is the dose your prescriber assessed you for. Changing it (even by staying at 5mg when you have been prescribed 7.5mg) is a medical decision, not a practical one. The NHS medicines page for tirzepatide sets out clearly that missed or altered doses should be discussed with the prescribing team rather than self-managed.

The situations that prompt a dose-change conversation are entirely normal. Nausea that is not settling after a couple of weeks, a feeling that the current dose is not yet working, or a clinical review flagging that your weight trajectory has stalled, all of these are reasons to contact your prescriber. At nume, that contact is available seven days a week; you do not have to wait for a scheduled appointment.

What your prescriber can do that a re-labelled pen cannot: they can issue a revised prescription at the appropriate strength, document the clinical rationale, and monitor your progress from there. A prescription for 5mg, if clinically indicated, is the proper route. You can find out more about getting 7.5mg Mounjaro through a regulated service or, if a step down is appropriate, the process for returning to a lower dose.

Step 3: How to get the right Mounjaro dose through a legitimate UK service

The only legal route to Mounjaro in the UK is a prescription issued following a genuine clinical assessment. That means a registered prescriber reviews your health history, current weight, any relevant conditions, and whether the requested dose is clinically suitable. No legitimate pharmacy can supply it any other way.

For an online pharmacy, the first check is whether it is registered with the GPhC. You can look up any pharmacy's registration (including ours) at the GPhC pharmacy register. nume's registration number is 9012878. If a seller cannot be found on that register, stop.

The MHRA has issued repeated warnings about counterfeit weight-loss pens sold through social media and unregistered websites, fake pens have contained insulin rather than the labelled medicine, and in 2025 the first illicit UK manufacturing site producing counterfeit tirzepatide was raided. Sellers offering these medicines without a prescription, or at prices well below what clinical assessment and genuine supply chain costs, are a serious red flag. Report anything suspicious at the MHRA's Yellow Card service.

When you start a consultation with nume, a GPhC-registered Independent Prescriber reviews your submission personally. Photo ID and live weight verification are part of the process. For dose increases or transfers from another service, clinical evidence is required before a higher strength is prescribed. Once approved, your pen arrives via DPD the next working day, tracked, in a plain box, with the Patient Information Leaflet inside.

Step 4: Check whether you are eligible before you consult

Mounjaro is licensed in the UK for adults managing their weight alongside a reduced-calorie diet and increased physical activity. The licensed criteria cover a BMI of 30 or above, or a BMI of 27 or above where at least one weight-related condition is present, for example, high blood pressure, high cholesterol, obstructive sleep apnoea, or prediabetes. For some ethnic backgrounds, BMI thresholds under UK guidance sit 2.5 kg/m² lower. NICE's appraisal of tirzepatide (TA1026) sets out the full clinical criteria that inform prescribing decisions.

A BMI that meets the threshold is a starting point, not a guarantee. The prescriber looks at the whole picture: your current health, any conditions that would make treatment unsuitable, and which dose is appropriate for where you are in treatment. If you are already on Mounjaro elsewhere and want to transfer your prescription, the process is straightforward, bring evidence of your current dose and recent weight. Our weight-loss treatment page outlines the options, and the consultation page is the place to start.

Pregnancy, breastfeeding and trying to conceive are situations where Mounjaro is not recommended. Tirzepatide is not licensed for anyone under 18. If any of those apply to you, or if you have questions about a specific condition, the consultation is the right place to raise them, our prescribers field exactly these questions regularly.