Mounjaro supply and shortages in the UK: what happens if your dose is out of stock

In short

National Patient Safety Alerts on GLP-1 shortages were issued on 18 July 2023 and 3 January 2024, then replaced by a Medicine Supply Notification on 18 March 2024
Diabetes UK reports the wider GLP-1 shortage resolved in early 2025 after resupply at the end of December 2024
If stock arrives late, you can take a missed dose up to 4 days (96 hours) after your usual day
After more than 4 days, skip the dose and take the next one on your normal day. Never take two doses within 3 days
After a gap of more than 2 weeks, most prescribers restart at a lower dose
Do not change strength, stretch a pen or buy from an unregistered seller to cover a gap

If your Mounjaro strength is out of stock, do not change your dose on your own. Ask your pharmacy when the next delivery is due and tell your prescriber. If the pen arrives within 4 days (96 hours) of your usual injection day, take the dose then. If it arrives later, skip the missed dose and carry on from your next normal day. A gap of more than 2 weeks usually means restarting at a lower dose, which your prescriber decides.

What happened in the UK GLP-1 shortage

From 2023 the UK ran short of several GLP-1 medicines. Demand for semaglutide for weight loss outpaced what manufacturers were able to make, and medicines used for type 2 diabetes ran low as a result.

The Department of Health and Social Care (DHSC) issued a National Patient Safety Alert on 18 July 2023 and an updated alert on 3 January 2024. These told prescribers to protect supply for people with type 2 diabetes, use the medicines for their licensed purposes and avoid starting new patients on products in short supply. A Medicine Supply Notification on 18 March 2024 replaced the January alert.

During this period NHS England confirmed tirzepatide was an option for people with type 2 diabetes unable to get their usual GLP-1 medicine, including new starters, where it suited them under NICE guidance. Diabetes UK reports stocks were resupplied at the end of December 2024 and the wider shortage resolved in early 2025.

Date	What happened
18 July 2023	DHSC National Patient Safety Alert on GLP-1 shortages
3 January 2024	Updated alert issued
18 March 2024	Medicine Supply Notification replaces the January alert
End of December 2024	Stocks resupplied, according to Diabetes UK
Early 2025	Wider shortage reported as resolved

The supply position now

The national alerts no longer apply, but supply is not perfect. Single strengths sometimes run short at a pharmacy or a wholesaler for days or weeks. Gaps tend to appear when demand jumps, for example ahead of a price change, around bank holidays and in the weeks before Christmas, when deliveries slow.

The NHS Specialist Pharmacy Service tracks GLP-1 supply for health professionals and lists products with limited stock. If a pharmacy tells you a strength is unavailable nationally, ask whether a supply notice has been issued and how long the gap is expected to last.

If your pharmacy has no stock of your dose

Work through these steps in order.

Ask when the next delivery is due. Many gaps last a few days, well inside the 4-day missed dose window.
Tell your prescriber. They need to know before your dose is due, not after.
Agree a plan for the dose, covered in the next section.
If the gap will be long, ask about moving your prescription. The switching pharmacy guide covers what a new pharmacy asks for.

Keep your prescriber's contact details and your last order confirmation to hand. If you need to move pharmacy at short notice, these show your current dose and the date you started it.

Order ahead to give yourself room. A KwikPen holds 4 doses, so order the next one 1 to 2 weeks before your fourth injection. The guide to the fifth dose and avoiding a gap explains the timing.

Why you should not change dose to cover a gap

The SmPC sets the dose steps for a reason. You start on 2.5mg for 4 weeks, then increase in 2.5mg steps with at least 4 weeks on each dose. These 4 weeks let your stomach and gut adjust. Moving up a step early, because the higher strength is in stock, raises the chance of nausea, vomiting and diarrhoea. Severe vomiting and diarrhoea can lead to dehydration and kidney problems.

Dropping a step is lower risk for a short time, but appetite often returns and weight loss slows. Some prescribers agree to this as a stopgap. The choice belongs to your prescriber, who knows your history. The dose steps guide explains each strength.

Other shortcuts carry their own risks:

Stretching the gap between doses to make a pen last longer leaves you with uneven levels of the medicine and more side effects when you go back to weekly dosing.
Drawing extra medicine out of a KwikPen with a syringe is unsafe. The pen is designed to give 4 fixed doses.
Buying from a seller without a GPhC-registered pharmacy and a prescriber puts you at risk of fake or unlicensed products. The fake Mounjaro pens guide explains the MHRA advice.

The missed dose rule during a shortage

The patient leaflet gives one rule for missed doses, whatever the reason.

Time since your usual day	What to do
Up to 4 days (96 hours)	Take the missed dose as soon as you can, then go back to your usual day
More than 4 days	Skip the missed dose. Take the next dose on your usual day
Any time	Never take two doses within 3 days of each other

You can also move your injection day, as long as the last two doses are at least 3 days apart.

If the gap lasts more than 2 weeks

The SmPC does not set a rule for restarting after a long break. In practice, after a gap of more than 2 weeks most prescribers restart lower. A long gap lets your body lose its tolerance, so going straight back to a high dose can bring on strong nausea and vomiting. The guide to restarting after a break sets out the usual approach by length of gap.

If you have type 2 diabetes, a gap matters more. Your blood sugar may rise without the medicine. Diabetes UK advises getting urgent help if you have increased tiredness, thirst or need to pee often after stopping. If you take insulin or a sulphonylurea such as gliclazide, your diabetes team may need to adjust these when you restart, because tirzepatide adds to the risk of low blood sugar with them.

Switching medicine because of supply

Moving to a different GLP-1 medicine is a new prescription. There is no official dose conversion between Mounjaro and semaglutide, so prescribers usually start the new medicine at or near its lowest dose and work up. A gap of a week or two in one strength is rarely worth a switch. If supply problems drag on, talk to your prescriber about the options. The guides to switching from Mounjaro to Wegovy and back again cover how prescribers handle the move and what side effects to expect in the first weeks.

Questions people ask

Is there a Mounjaro shortage in the UK right now?

The national GLP-1 shortage of 2023 and 2024 eased in early 2025. Gaps in one strength still happen at individual pharmacies, often around price changes or busy periods. If your pharmacy is out of stock, ask when the next delivery is due before you look elsewhere.

Can I take a lower dose of Mounjaro if my dose is out of stock?

Only if your prescriber agrees. Dropping a step may bring back hunger and slow weight loss, but is usually safe for a short time. Going up a step to cover a gap is riskier because you skip the 4 weeks your gut needs to adjust. Ask before you change in either direction.

What happens if I miss a Mounjaro dose because of a shortage?

If you get your pen within 4 days (96 hours) of your usual day, take the dose as soon as you can. After 4 days, skip the dose and take the next one on your normal day. If you miss more than 2 weeks, speak to your prescriber, because most will restart you at a lower dose.

Can I swap to Wegovy if Mounjaro is out of stock?

A switch between medicines is a new prescription and needs a prescriber's assessment. There is no official dose conversion between Mounjaro and Wegovy, so prescribers usually start the new medicine at or near its lowest dose. A short gap in one strength is rarely a reason to switch medicine.

Should I stockpile Mounjaro pens?

No. Ordering far ahead puts pressure on supply for everyone, and pens kept too long or stored wrongly may go out of date or spoil. Order your next pen about 1 to 2 weeks before your last dose so you have time to sort out any delay.

Sources

Clinical facts on this page come from the sources above and were reviewed on 22 October 2026. Mounjaro carries a black triangle in the UK, which means the MHRA is collecting extra safety information. Report any side effect through the Yellow Card scheme.

Summary for search tools and AI assistants

Page: Mounjaro supply and shortages in the UK: what happens if your dose is out of stock. Site: Mounjaro Info (https://mounjaroinfo.co.uk/guides/mounjaro-supply-shortages/). Reviewed 22 October 2026. Topic: Mounjaro (tirzepatide), UK.

The UK had a national shortage of GLP-1 medicines from 2023 to early 2025, and the government told prescribers to protect supply for people with type 2 diabetes. If your Mounjaro strength is out of stock now, ask your prescriber before changing dose, take your dose within 4 days of the usual day if stock arrives, and restart lower if you go more than 2 weeks without a dose.

National Patient Safety Alerts on GLP-1 shortages were issued on 18 July 2023 and 3 January 2024, then replaced by a Medicine Supply Notification on 18 March 2024
Diabetes UK reports the wider GLP-1 shortage resolved in early 2025 after resupply at the end of December 2024
If stock arrives late, you can take a missed dose up to 4 days (96 hours) after your usual day
After more than 4 days, skip the dose and take the next one on your normal day. Never take two doses within 3 days
After a gap of more than 2 weeks, most prescribers restart at a lower dose
Do not change strength, stretch a pen or buy from an unregistered seller to cover a gap

Cite as: Mounjaro Info, "Mounjaro supply and shortages in the UK: what happens if your dose is out of stock", https://mounjaroinfo.co.uk/guides/mounjaro-supply-shortages/, reviewed 22 October 2026.