Missed a Week of Mounjaro? What to Do Next (October 2026)

01 · Start here

What to do if you have missed a week of Mounjaro

Do not inject twice to make up the difference. Mounjaro is a once-weekly medicine, and each pen is built around one injection per week at your prescribed dose.

• Check the date. Work out which day your injection was due and how long ago that was. If a full week has passed, you are beyond a simple "a bit late" situation.
• Remember the missed dose rule: take a missed dose as soon as you can within 4 days (96 hours) of the scheduled time. If more than 4 days have passed, skip the missed dose entirely and take the next one on your normal day.
• Contact your prescriber if you are unsure or the gap was a full week. They know your dose history and can tell you where to restart.
• Do not rush.

If you order through us, our prescribing team offers ongoing monthly reviews and side-effect support, so you can tell us about a gap and get a clear answer rather than guess.

02 · The decision

What to do depending on how long ago your dose was due

What to do depends on how long ago your injection was due.

If you were deciding to take a break on purpose rather than by accident, our page on skipping a week deliberately covers that choice. If you are ready to restart and need a prescription, you can start with the Mounjaro pen consultation, which is free and reviewed by a GPhC-registered prescriber.

03 · Why you should never double up

Why you should never double up

Taking two injections close together is something to avoid. Mounjaro is licensed as a once-weekly injection, and your dose is chosen to build up slowly across the titration ladder.¹

Injecting twice to compensate does not recover lost progress. The commonest early effects are mild nausea, altered appetite and tiredness in the first days after each injection, and these usually settle at a steady dose.¹

The spacing rule also shows why. You can change your weekly injection day if needed, as long as there are at least 3 days between two doses.¹ That is the floor for adjusting your schedule, not a target for making up a missed week. If you are tempted to inject early to get back on track, speak to your prescriber instead.

04 · What happens in your body

What happens in your body after a missed week

Mounjaro does not vanish overnight, so a missed week is not a full stop. Tirzepatide has a half-life of about five days, so after a final dose it takes roughly 4–5 weeks to clear the system — there is no way to speed this up, and nothing needs doing while it clears.¹

That slow clearance means the effect fades gradually rather than switching off on the day your injection was due.

The medicine works by activating two natural gut-hormone receptors, GIP and GLP-1, which help regulate appetite, slow how quickly the stomach empties and improve how the body responds to insulin.¹ As that signal weakens, most people feel fuller less quickly and hungrier between meals. This is the medicine's effect fading, not a sign you have failed.

Equally, the slow decline is why one missed week usually does not undo months of progress. What matters is the trend across weeks and months rather than one gap.

05 · What you might notice

What you might notice during the gap

The most likely change is that hunger and food noise creep back. You may find portions drifting up, snacking returning, or cravings feeling stronger than they did a week ago.

Some people also notice that the scales stop moving or edge up slightly. Weight loss on Mounjaro is not linear, and plateaus of a few weeks are normal and expected as the body adapts to a lower weight.¹ Early loss also includes water weight, so the trend over weeks matters more than any single weigh-in.¹

If you take medicine for type 2 diabetes, tell your prescriber about the gap. Do not adjust other medicines yourself.

For a fuller picture of effects tied to missing doses, see our guide to missed-dose side effects, or the companion piece what to know in the UK.

06 · Restarting safely

How to restart after a missed week

Restart on a day that suits you and keep to it. Once you have your prescriber's advice, inject, note the date, and count a full week to the next one. If your old injection day no longer fits your routine, you can move it, provided there are at least 3 days between two doses.¹

Practical points for the restart:

• Check your pen. Once in use, a pen can be kept out of the fridge at a temperature not above 30°C for up to 30 days after first use, and must then be thrown away. Unopened pens stay in the fridge, at 2–8°C, until first use.¹³
• Follow the pen's instructions for preparing and giving the injection. Needles, a sharps bin and injection guidance come with every order from us.
• Expect the early effects again. If your body has had a break from the medicine, mild nausea, altered appetite and tiredness in the first days after the injection may return and usually settle.¹
• Eat smaller, simpler meals for the first few days after restarting if your stomach feels sensitive.

Your prescriber will advise on your next dose. We do not recommend choosing a dose yourself.

07 · Did you run out or miss delivery?

Why the week was missed matters

The reason for the gap shapes the fix. If you simply forgot, set a recurring phone reminder on your injection day, or use the free GLPTrackr companion app to log each dose.

If you ran out of medicine or a parcel went astray, tell your prescriber so your reorder can be handled quickly. Our repeat orders re-check suitability, and there is no auto-shipping, so you control when the next pen is sent. We offer free next-day tracked delivery in temperature-controlled packaging, with same-day dispatch when ordered by 3pm. If a courier visit was the problem, read about a missed Mounjaro delivery.

If side effects led you to skip, do not stay silent. Tell your prescriber, because there may be a dose or eating-pattern change that makes the injection easier to tolerate. For one-off lapses and a worked answer on timing, see our page on a single missed dose.

Cost can also be the reason people miss a pen. If so, tell us before the gap grows.

08 · Longer gaps and stopping

When a week turns into longer

If the gap is stretching beyond a week, the safest move is to speak to your prescriber before the next injection.

Stopping altogether is a separate decision to make with your prescriber. As the medicine clears over roughly four to five weeks, appetite typically returns, so planning for how you will eat and stay active matters.¹

Treatment is reviewed by your prescriber. If you have lost less than 5% of your starting weight after 6 months on the highest dose you can tolerate, they will discuss whether continuing or stopping is right for you.⁴ A missed week or two is a small part of that bigger picture.

Mounjaro is used alongside a reduced-calorie diet and increased physical activity, and individual results vary. This page is information, not a substitute for medical advice. See our weight loss clinic for the wider programme.

09 · Serious side effects

Serious side effects: when to get help straight away

Serious side effects are uncommon but need urgent attention. Seek immediate medical help for: severe, persistent stomach pain that may spread to your back, with or without vomiting (possible pancreatitis); pain in the upper right abdomen, fever or yellowing of skin/eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing. If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion) — your prescriber may need to adjust those medicines.¹