Mounjaro supply issues in the UK: causes, current status and your options

Why has the UK faced Mounjaro supply problems in the first place?

The short answer is that demand arrived faster than Eli Lilly's production lines could scale. Mounjaro received its UK licence for weight management in November 2023, and when NICE recommended tirzepatide (TA1026) in December 2024 (making it the first injectable weight-loss medicine to receive a positive NICE appraisal based on its own trial evidence) the prescription volume climbed sharply. Manufacturing a biological medicine at this scale takes considerable lead time; Lilly cannot simply turn up production overnight.

The picture has been complicated further by a separate pricing change. From 1 September 2025, Lilly raised its UK list price substantially across the dose range, which shifted prescribing patterns and, in turn, altered which strengths were moving most quickly through the supply chain. If you want a fuller picture of how availability has evolved, our page covering Mounjaro supply in the UK explains the background in more detail. The result has been uneven availability: some doses have been consistently obtainable while others disappear from certain wholesalers for weeks at a time.

The MHRA maintains a Drug Safety Updates index that covers communications on GLP-1 medicines, and official shortage information is published through DHSC and NHS England channels. Checking these rather than forum reports gives you a more reliable picture of where things actually stand.

Which Mounjaro doses have been most affected by stock shortages?

Not every pen on the six-dose ladder has been equally hard to find. The 2.5mg and 5mg starter strengths have generally remained more available, partly because a smaller proportion of patients are at those doses at any one time and partly because demand for them has been more predictable. Mid-range doses, particularly 7.5mg and 10mg, have seen the most frequent gaps; the higher doses (12.5mg and 15mg) have had periods of tightness too, though availability shifts from month to month.

This uneven pattern creates a practical problem. Someone who has titrated up to, say, 10mg and then cannot source it faces a genuine clinical dilemma: step down temporarily, pause entirely, or try to source from elsewhere. None of those paths should be taken without talking to a prescriber first. Stepping down a dose isn't simply a commercial decision, it affects the appetite-regulation effect you've built up, and restarting after a gap may require re-titration. You can read more about what a three-month Mounjaro supply arrangement can mean for continuity of treatment.

A regulated pharmacy with direct relationships in the licensed UK supply chain is better placed to anticipate and navigate these gaps than a patient searching independently. That is worth factoring in when you choose where to get your prescription.

What should you actually do if you can't get your current dose?

The first step is to contact whoever issued your prescription before doing anything else. If you're with a private provider, reach out to their aftercare team. If your prescription comes via a GP, call the practice. The worst responses to a supply gap are the ones taken without clinical input: ordering from an unverified seller, switching to a different medicine mid-titration, or simply stopping abruptly. Our dedicated page on common Mounjaro issues covers these scenarios and what your options are if things don't go to plan.

The MHRA has issued clear warnings about counterfeit tirzepatide pens circulating in the UK through social media and unregistered sellers. In October 2025, the first illegal UK manufacturing site producing fake tirzepatide pens was raided in Northampton, and investigators found approximately 20 million doses of illegally traded weight-loss medicines worth around £45 million had been intercepted across 2025. A pen bought from an unverified source may contain the wrong substance, the wrong concentration, or nothing therapeutic at all. If you come across what looks like a bargain or a seller who can supply pens that legitimate pharmacies can't, that disparity is itself a warning sign.

You can verify any online pharmacy is GPhC-registered at the GPhC pharmacy register before handing over payment or personal details. For broader context on accessing tirzepatide safely through regulated channels, our tirzepatide supply guide covers the landscape in more detail.

Is there anything that can legitimately bridge a supply gap?

Your prescriber may consider a temporary dose adjustment, a structured pause, or, in some clinical situations, whether a different licensed weight-management medicine is appropriate for you. These are individual decisions. What works for one person won't be right for another, and the right answer depends on how long you've been on treatment, how you've responded, and whether any other health factors are in play. It is also worth being aware that some patients report visual changes while using tirzepatide, so if you notice anything unusual with your sight, our page on Mounjaro and eye issues sets out what to look out for and when to seek advice.

One practical thing that does help: if you collect your prescription the same week it's issued rather than letting it sit, you give the pharmacy a better chance of fulfilling it from current stock. Similarly, maintaining a short buffer (one pen ahead rather than leaving it until you've used the last dose) gives you a few weeks of flexibility if your usual supplier runs short. Our prescribers hear this suggestion from patients who've found it genuinely useful, usually after they've experienced a gap once.

For context on how pricing and availability interact, the Mounjaro cost page covers what drives price variation across the private market. And if you're weighing up whether to stay on tirzepatide or explore other options, our weight-loss treatment overview sets out what's currently licensed in the UK.

If you have questions about your specific situation or want to understand how a clinical review could help, you can get in touch with our team directly. When you're ready to take the next step, starting a free consultation means a GPhC-registered prescriber reads your details the same day, a real clinician, not an automated queue.