Didn't Get Full Dose of Mounjaro? What To Do Next (October 2026)

01 · Start here

What to do if you didn't get your full dose of Mounjaro

The safest first step is to stop, avoid a repeat injection, and get advice. Mounjaro is a once-weekly medicine, and the licensed missed-dose rule is clear: never take two doses within 3 days of each other.¹¹³ A 'top-up' injection straight after a doubtful one would break that rule.

Work through these steps in order:

• Keep the pen. Do not throw it away. Your prescriber or pharmacist may want to know which pen, which dose and how it looked.
• Write down what happened. Date, time, the dose you dialled, the injection site and anything unusual, such as the pen not turning or you being interrupted.
• Do not inject again to compensate. Wait for your normal injection day unless a clinician tells you otherwise.
• Contact your prescribing team or pharmacy. Customers can reach us Monday to Friday, 9am to 5pm, on 0333 207 0413 or at support@everydaymeds.co.uk, and our prescribing team can talk through your next dose.

If you are not yet a customer and want a clinician to look at your situation, you can start your free consultation; it is reviewed by a GPhC-registered prescriber.

02 · Match your case

Which situation are you in?

The right action depends on what actually went wrong.

03 · Cost and supply

Replacing a pen or ordering the next one

If a pen turned out to be short or faulty, tell us promptly. Dispensed prescription medicines cannot be returned except where they are faulty, damaged or the wrong item, and you need to contact us within 3 days.

For a normal reorder, the Mounjaro pen costs £169.99 at the 2.5mg starting dose and £218.99 at 5mg. Prices were checked 11 October 2026, and all six doses are in stock. A new customer's first order is £40 off with code FIRST40, and an automatic £25 reorder discount applies to every future order (code DOSE25). Repeat orders re-check suitability, and there is no auto-shipping, so you control when the next pen arrives. You can see every strength on our Buy Mounjaro page.

04 · Reading the pen

How the KwikPen shows your dose

The pen shows your dose in the window, and the number there is what counts. Many people worry about clicks because they hear them while dialling, but they are not a measure of dose. Our guides on how many clicks is a full dose and clicks on the 2.5mg KwikPen explain this in more detail.

05 · Missed versus partial doses

Missed dose rule versus an uncertain injection

A missed dose and a doubtful dose are treated differently. If you missed a dose, take it as soon as you can within 4 days (96 hours) of the scheduled time, then carry on with your usual day.¹ If more than 4 days have passed, skip it entirely and take the next one on your normal day. Never take two doses within 3 days of each other.¹

An injection you are unsure about is not a missed dose, because you did inject. Because the same 3-day spacing rule applies, repeating it soon afterwards would put two doses closer together than the licence allows. That is why the answer is to get advice rather than to guess. Your prescriber knows your dose, your history and how you have tolerated treatment.

If you want to move your injection day afterwards, you can, provided at least 3 days (72 hours) have passed since your last dose.¹

06 · Why not top up or microdose

Why you should not top up or microdose

Topping up or splitting doses is not a safe workaround. It is not licensed, not supported by the pen's design and not endorsed by any UK regulator.¹ Altering doses outside the licence means unknown dosing accuracy and no safety data.

The licensed ladder already protects tolerability. Everyone starts on 2.5mg once a week, and the dose goes up after at least 4 weeks to 5mg, then in 2.5mg steps at a minimum of 4-week intervals, to a maximum of 15mg.¹ Our pages on the smallest Mounjaro dose and upping your dose cover how titration works.

07 · Feeling no effect

If the real worry is that it is not working

Feeling little after a dose does not mean you missed part of it. The 2.5mg starting weeks are about adjustment: some people notice appetite change and early loss in week one, others feel little until a higher dose, and both are normal.¹ Early loss includes water weight, so the trend over weeks matters more than any single weigh-in.

Weight loss on Mounjaro is gradual by design, and most measurable progress builds from 5mg onward, month by month.¹ In the SURMOUNT-1 trial of 2,539 adults, people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.² These are trial averages, individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity.

Your prescriber reviews response: 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.¹ If you are asking whether it works at all, read Mounjaro didn't work for me and our guide to the beginner dose.

08 · Storage and handling

Check how the pen was stored

Poor storage is worth ruling out if a dose seemed to go wrong. Keep pens in a fridge at 2 to 8°C and never freeze them. Once in use, a pen can be kept out of the fridge not above 30°C for up to 30 days, after which it should be discarded.¹³ Keep the cap on to protect it from light, and never use a pen that has been frozen.

Unopened pens should stay in the fridge and keep until the expiry date printed on the box. If an unopened pen has been out of the fridge, check with the pharmacy before using it rather than relying on a remembered day limit, because figures circulating online often come from other countries' labels.¹³ If you travel, carry pens in hand luggage, not the hold, where it can fall below freezing.

09 · When to seek advice

When to contact a clinician

Contact your prescriber or pharmacy whenever you are unsure how much you received, the pen behaved unexpectedly, or you are considering any extra injection. Do the same if you have symptoms you are worried about after a dose. 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 or eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing. The commonest early effects are mild nausea, altered appetite and tiredness in the first days after each injection, and these usually settle.¹

You can report suspected side effects through the MHRA Yellow Card scheme.¹⁹ Our aftercare includes ongoing monthly reviews, dose-titration support and side-effect support from the prescribing team, and our free GLPTrackr app helps you log injection dates and doses so you always have a record. Our weight loss treatments page lists the other options.

This page is information, not a substitute for medical advice. Mounjaro is a prescription-only medicine supplied after an online consultation reviewed by a GPhC-registered prescriber.