Trying to get the rest of the Mounjaro out of the pen? Here's what's actually happening

Is there really medicine left in the pen after the last dose?

Yes, almost certainly, but it's not an extra dose. Eli Lilly designs each Mounjaro KwikPen with what's called overfill: a small volume of liquid that sits beyond the point the pen mechanism can reliably deliver. It's there to guarantee you receive four complete, accurately measured doses, not as a bonus injection. If you're curious about how to get the last bit out of a Mounjaro pen, the short answer is that attempting to extract that residual liquid is not recommended and could mean injecting an unknown, unmeasured quantity rather than the calibrated amount your prescriber has approved for your treatment plan.

If you're concerned you may have received an incomplete dose due to a bent needle, interrupted injection, or pen malfunction, that's a different matter. In that case, don't attempt a second injection from the same pen, contact your prescriber for guidance. Our clinical team at nume support is available seven days a week if you're a current patient with a question like this.

The NHS tirzepatide information page and the Patient Information Leaflet inside every box both cover what to do if a dose is missed or appears incomplete. Always check those first.

What does the legal route to Mounjaro in the UK actually look like?

Mounjaro (tirzepatide) is a prescription-only medicine under the Human Medicines Regulations 2012. That means there is one legal route to obtaining it: a prescriber assesses your health, decides it's appropriate for you, and issues a prescription. No other route exists under UK law.

In practice, this means either your GP refers you through the NHS (where access is currently phased and criteria are strict, as explained on our page about when Mounjaro is available on the NHS) or you go through a regulated private pharmacy service. With the private route there's no waiting list, but the clinical assessment is equally real. A prescriber reviews your consultation, your medical history, and your current dose evidence before anything is issued. That's not optional admin; it's what keeps you safe.

If you're sourcing repeat treatment or wondering about buying Mounjaro online, the same rules apply: a prescription from a qualified prescriber must precede every supply.

How do you check whether an online pharmacy is legitimate before you order?

Every pharmacy operating legally in the UK must be registered with the General Pharmaceutical Council. You can verify any pharmacy, including ours, directly on the GPhC register, nume's registration number is 9012878. That link takes you straight to our entry. If a pharmacy you're considering isn't listed there, don't order from them.

The MHRA has issued repeated warnings about counterfeit weight-loss pens sold online and via social media, fake pens have in some cases contained insulin rather than tirzepatide. In October 2025, a site in Northampton producing counterfeit tirzepatide pens was raided, and around 20 million doses of illegally traded medicines (worth roughly £45 million) were seized across 2025 enforcement action. The red flags to watch for: sellers offering Mounjaro without a clinical assessment, prices far below anything a regulated pharmacy can sustain, and discount codes or social-media offers, none of those belong near a prescription medicine. Report suspect sellers at the MHRA's Yellow Card service.

For a wider look at what a reputable supply process involves, our about us page sets out how nume operates, including our clinical infrastructure and GPhC registration.

Who can get Mounjaro prescribed privately, and how does nume's process work?

Privately, Mounjaro is licensed for adults with a BMI of 30 or above, or 27 and above where at least one weight-related condition is present, conditions such as high blood pressure, type 2 diabetes, high cholesterol, or obstructive sleep apnoea. Lower BMI thresholds may apply for some ethnic backgrounds under UK clinical guidance. A BMI figure alone doesn't determine the outcome; a prescriber weighs up the full picture.

At nume, the process is straightforward. You complete a free clinical consultation, questions about your health, current medicines, and weight history. A GPhC-registered Independent Prescriber reads that in full the same day. Not a triage algorithm: a named clinician. If treatment is clinically suitable, they issue a prescription and your pen ships the same day you order, provided you order before 12pm on a working day. It arrives by DPD the next working day, tracked, in packaging that gives nothing away, useful if it's sitting in the fridge door alongside the usual household contents.

Existing patients transferring from another provider, or requesting a dose increase, are asked to provide evidence of their current treatment first. That step exists for your safety. Our prescribers, including our lead clinician, oversee every case personally. To see the full range of treatments available and to start your free consultation, visit our weight-loss treatments page. For practical guidance on making the most of your treatment once it's in hand, our pages on how to get the best from Mounjaro, how to get the most out of Mounjaro, and how to get the Mounjaro jab are all good next reads, alongside our existing guide on getting the best out of Mounjaro.