How should pharmacies handle GLP-1 shortages and substitutions?

Is there a GLP-1 shortage right now?

No. As of April 2026 there is no national shortage of semaglutide or tirzepatide in the UK, and the last one ended more than a year ago. That matters for how you handle a gap: a missing strength today is a local supply problem, not a rationing problem, and the tools for it are ordinary ones.

The national shortage ran from 2023 into 2024. A DHSC and NHS England patient safety alert in July 2023 told prescribers to limit new starts on GLP-1s for type 2 diabetes and not to prescribe them off-label for weight loss. On 3 January 2024 the alert was extended to the end of 2024, as The Pharmacist reported. Byetta was discontinued in March 2024 and Victoza was out of stock. Wegovy and Saxenda stayed available through specialist services.

The picture since then has been about demand and price, not manufacturing. In August 2025 Lilly limited orders ahead of its 1 September price rise. The Department of Health and Social Care said it was not aware of supply issues with any strength of Mounjaro. When Bydureon BCise was discontinued in October 2025, the DHSC notice said alternative GLP-1 and dual GIP/GLP-1 agonists remained available. The table sets out the events that shape supply now.

The demand side is the thing to watch. NICE's type 2 diabetes update on 19 February 2026 opened GLP-1 and tirzepatide treatment to people diagnosed before 40, people living with obesity and people with cardiovascular disease. Its final draft guidance on 1 April 2026 recommends Wegovy 2.4 mg for people with a history of heart attack, stroke or peripheral arterial disease and a BMI of 27 or more. About 1.2 million people could be eligible. ICBs must fund it within 90 days of the final publication. Two demand shocks of that size, on top of a private market of well over a million users, are how the next shortage would start.

What can you change without a new prescription?

Almost nothing about the medicine itself. Regulation 214(1) of the Human Medicines Regulations 2012 says a person may not sell or supply a prescription-only medicine except in accordance with a prescription given by an appropriate practitioner. For NHS prescriptions there is a second rule. Paragraph 8(1) of Schedule 4 to the NHS (Pharmaceutical and Local Pharmaceutical Services) Regulations 2013 says drugs must be provided in accordance with the order on the prescription form.

There is no generic substitution in UK law, and a GLP-1 has no generic anyway. The molecule, the brand, the strength and the form on the prescription are what you may supply. What you may vary is limited to quantity and, under a protocol, to the specific alternatives the protocol names.

Parliament has looked at widening this. In May 2024 the Health and Social Care Committee urged ministers to let community pharmacists make dose and formulation substitutions for out-of-stock medicines within three months. The government said it had not decided. As of April 2026 the law has not changed, and the position for GLP-1s is the one in the table.

Is there a Serious Shortage Protocol for GLP-1s?

No. Regulation 226A of the Human Medicines Regulations 2012, in force since 9 February 2019, lets ministers issue a Serious Shortage Protocol when the UK faces a serious shortage of a named medicine. The NHSBSA publishes every protocol issued under it. None has ever covered semaglutide, tirzepatide, liraglutide or dulaglutide.

The protocols in force in April 2026 are for Estradot patches in four strengths (SSP079 to SSP082) and Creon 10000 and 25000 capsules (SSP060 and SSP061). A protocol only lets you supply the specific alternative, strength, form or quantity it names, and only if you judge that supply reasonable and appropriate for the patient. The patient must agree. If you decide the alternative is not appropriate, you refer the patient back to the prescriber. Our guide to when pharmacists can substitute under an SSP covers the mechanics.

One point trips up private clinics. Community Pharmacy England confirms that SSPs apply to any valid prescription that meets the requirements of the 2012 Regulations, so they cover private prescriptions as well as NHS ones. That would matter for a GLP-1 protocol if one were ever issued. Until then, the answer to a patient who asks you to "just give me the other one" is the same on both sides of the counter.

What to do when the strength is out of stock

Treat it as a prescriber problem you are solving, not a dispensing decision you are making. The sequence below keeps you inside regulation 214 and gets the patient a dose on time. It is the GLP-1 version of the routine in our shortages workflow guide.

Do not improvise on dose. A prescriber may reasonably decide that a patient on 10 mg should drop to 7.5 mg for a month rather than miss doses. They may decide a patient on 2.4 mg Wegovy should hold at 1.7 mg. Those are prescribing decisions with a licensed dose behind them. Doubling pens of a lower strength is not the same medicine as the higher pen, and it is not yours to authorise.

Can you switch between Mounjaro and Wegovy?

Only the prescriber can, and only with a new prescription. Tirzepatide is a dual GIP and GLP-1 receptor agonist; semaglutide is a GLP-1 receptor agonist. They are different molecules with different titration ladders. Neither SmPC gives a dose equivalence, and the Wegovy SmPC says co-administration with any other GLP-1 receptor agonist is not recommended.

In practice a switch means a new start. Mounjaro begins at 2.5 mg for four weeks and rises in 2.5 mg steps at least four weeks apart to a maintenance dose of 5 mg, 10 mg or 15 mg. Wegovy climbs from 0.25 mg through 0.5 mg, 1 mg and 1.7 mg to 2.4 mg over 16 weeks. The prescriber chooses whether the patient re-titrates from the bottom or starts part way up, and takes responsibility for the gastrointestinal risk of doing so. Your job is to confirm the last dose taken and the date, and to make sure the patient understands the new pen is not a like-for-like replacement.

For a private patient this usually means a fresh consultation, not a phone call. The GPhC's February 2025 guidance on services at a distance requires the prescriber to independently verify weight, height or BMI and to check the medical history before supplying a weight-management medicine. A switch is a new supply decision, so those checks apply again. See our summary of the verification duties.

Missed doses, gaps and dose stretching

The SmPCs give you the script for a short gap. Mounjaro: a missed dose can be taken within four days; after that, skip it and take the next dose on the usual day. Wegovy: within five days; after that, skip it. The Wegovy SmPC adds that if more doses are missed, a lower dose for re-initiation should be considered. That decision belongs to the prescriber, which is another reason to make the call early rather than after the patient has been off treatment for a month.

The bigger risk is what patients do to stretch supply. A LloydsPharmacy Online Doctor survey of 2,000 adults, reported on 28 January 2026, found that among those who had used a GLP-1, 47% had changed their dosing to save money. 24% had taken smaller doses than prescribed and 23% had combined leftover product from pens to make extra doses. 28% had knowingly bought from an unlicensed seller. A pharmacy facing a stock gap is talking to exactly the patients most likely to do this.

Private prescriptions and online supply

The law is the same; the logistics are different. Regulation 214 does not distinguish NHS from private prescriptions, and SSPs cover both. A private prescriber can authorise a change by phone and follow with a prescription within 72 hours, exactly as a GP can. The difference is that many private patients get their prescription and their medicine from the same online provider. When that provider is out of stock, they turn up at a local pharmacy with no prescription at all.

Regulation 225 exists for that patient. You must interview them and be satisfied on three points: there is an immediate need, a prescription cannot be obtained without undue delay, and a UK prescriber has prescribed the medicine before. If so, you may make an emergency supply of up to 30 days' treatment. For a four-dose Mounjaro KwikPen that is one pen. You must record the supply under regulation 253 and label it as an emergency supply. Ask to see the previous prescription or the provider's dispensing label, confirm the current dose, and record how you verified it.

What you should not do is become the second prescriber. A patient who is titrating with one clinic and wants a top-up prescription from your own prescriber is asking you to take on a supply you cannot see the history of. The GPhC guidance expects a two-way consultation, verified measurements and a check of the medical history, including contact with the GP or regular prescriber with consent. Our guide to what to tell patients during shortages has wording for the conversation.

The alternative the patient is weighing is the illegal market. The MHRA seized £45 million of illegally traded medicines in 2025, nearly 20 million doses, including more than 5,000 GLP-1 units, as The Pharmaceutical Journal reported on 26 January 2026. Andy Morling, the MHRA's deputy director of enforcement, put it plainly: if something looks or feels wrong, it probably is, and patients should always use a registered pharmacy. A pharmacy that can offer a lawful bridge, a prescriber call and a date is the reason they do.

Key takeaways

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