Why Mounjaro keeps running out of stock — and what to do about it

What is actually causing the Mounjaro shortage?

The short answer is that far more people want tirzepatide than Eli Lilly's global production lines can currently supply. When NICE recommended Mounjaro for weight management in December 2024 (confirming its place in UK clinical practice) interest surged well beyond what had already been a rapidly growing private market. Manufacturing the active ingredient at scale, filling and quality-testing each KwikPen, and moving product through licensed distribution channels all take time. Eli Lilly has publicly committed to expanding capacity, and some investors tracking that commitment have looked into how to buy shares in Mounjaro as the company scales production over the coming years.

Shortages tend to cluster around specific dose strengths. Higher doses such as 10mg and 12.5mg have been affected more often, partly because they represent the later stages of treatment for people who have already titrated up over many months. Starter doses (2.5mg and 5mg) have generally been more available, though this shifts. The current Mounjaro stock picture changes frequently, so checking directly with a registered pharmacy gives you a more accurate read than news headlines from weeks ago.

It is also worth knowing that the NHS rollout of tirzepatide through GP practices, which began in April 2026, adds further volume to UK demand. More patients now qualifying for treatment through the NHS means more pens are needed across the whole system, tightening private-market availability in parallel.

What the shortage means for your treatment (the decision you're actually facing

A question our prescribers hear most weeks is some version of: "My pharmacy can't get my dose) should I skip it, take a different strength, or switch medicines?" None of those options is straightforward, and none should be made without talking to a prescriber first.

Skipping doses isn't recommended. Tirzepatide's appetite-regulating effect builds steadily; an unplanned gap can disrupt progress and increase the likelihood of side effects when treatment restarts. Taking a different strength without clinical guidance carries its own risks, dropping to a lower dose to maintain continuity is sometimes clinically appropriate, but it is a decision that belongs to your prescriber, not to the pharmacy shelf. Switching to a different GLP-1 medicine is sometimes considered, though the two available injectable options work differently and the right choice depends on your individual medical history.

If you are currently on treatment and your supply has been disrupted, contact your prescribing pharmacy or prescriber before doing anything else. If you are considering starting for the first time and wondering whether shortage makes that pointless, it is worth noting that lower doses used at the start of treatment have generally remained more accessible. You can check which Mounjaro strengths are currently available to understand what a new course might look like right now.

How to find genuine Mounjaro safely during a shortage

Shortage creates pressure, and pressure is exactly when counterfeit products find a market. The MHRA has warned repeatedly about fake tirzepatide pens circulating online and through social media channels, in 2025 alone, enforcement operations seized approximately 20 million doses of illegally traded weight-loss medicines worth around £45 million, including the UK's first illicit manufacturing site for counterfeit tirzepatide pens, discovered in Northampton. Fake pens have been found to contain insulin and other unlabelled substances.

The only safe way to buy Mounjaro is through a pharmacy you can verify on the GPhC pharmacy register. Red flags include sellers offering pens without requiring a prescription, prices conspicuously below the market range, and payment via informal channels. Any pharmacy offering Mounjaro without first conducting a clinical assessment is operating outside the law. For context on what legitimate private treatment typically costs, the Mounjaro cost page sets out the realistic market range and what a transparent price should cover.

If you want to understand broader stock patterns (which pharmacies tend to hold which doses and how availability has moved recently) a guide to where Mounjaro is in stock covers the practicalities in more detail. The MHRA's Yellow Card scheme also allows you to report suspect sellers: yellowcard.mhra.gov.uk.

What comes next, and how to start treatment through a regulated service

Shortages will ease as manufacturing scales. In the meantime, the safest path is to work with a GPhC-registered prescribing service that has direct relationships with licensed UK suppliers and can tell you, honestly, what is and isn't available before you pay anything.

At nume, every order begins with a free consultation reviewed by a GPhC-registered Independent Prescriber (a real clinician, not automated decision software) on the same day. We source only through the licensed UK supply chain, and we will tell you upfront if a particular dose is unavailable rather than substituting without your knowledge. If you are ready to explore whether treatment is clinically suitable for you, start your free consultation and our prescribers will take it from there. You can also read more about how to buy Mounjaro online through a regulated pharmacy, or visit our Mounjaro overview for a fuller picture of how the medicine works. Our about us page explains the pharmacy and clinical infrastructure behind every prescription we issue.