Mounjaro Injection Instructions: UK Guide (October 2026)

01 · The short version

How do you inject Mounjaro? The core answer

You inject Mounjaro under the skin once a week using a pre-filled KwikPen. It goes in on the same day each week, at any time of day, with or without food.¹

The detail that trips people up is not the injection itself. It is choosing a site, setting the dose correctly on the dial, remembering what to do after a missed dose, and storing the pen sensibly.

Every order we dispatch includes needles, a sharps bin and injection guidance. The physical press-and-hold sequence differs slightly between pen designs, so follow the pen's own instructions and the patient information leaflet for that part.¹³ For a closer walk through the device itself, see our Mounjaro injection pen instructions.

02 · What you actually need to decide

The decisions you are really facing

Which day of the week suits you? Which injection site will you start with? What do you do if the schedule slips? And where will the pen live between doses? Getting these right in advance makes the routine boring, which is exactly what you want from a weekly medicine.

Choosing the day. What matters is the same day each week. Many people pick a weekend morning so that early side effects fall on days off, but that is a convenience, not a rule. If your circumstances change you can move the day, as long as at least 3 days (72 hours) have passed since your last dose.

Choosing the site. There are three licensed areas, and the back of the upper arm only works if someone else gives the injection. Pick one area, then move around within it and between areas so the same patch of skin is not used dose after dose.

Coping when it goes wrong. A forgotten dose, a delayed delivery, a holiday or a warm car are all ordinary events. The licensed rules are clear and short, and none involve improvising with the pen.

Storage. The fridge is the default home for the pen. A pen that has been started has a more forgiving in-use window, which makes travel straightforward.

If you are already prescribed Mounjaro and need a pen, the Mounjaro pen with prices and consultation page shows the live range. As an example, your first 2.5mg pen costs £129.99 with code FIRST40 (standard price £169.99), and all six strengths are in stock. Ordering follows a free online consultation reviewed by a GPhC-registered prescriber, and our wider weight loss clinic page explains the wider service.

03 · Is this relevant to me

Your leaflet and prescriber come first

General information is not a replacement for the leaflet in your box or the advice of your prescriber. Mounjaro is a prescription-only medicine used alongside a reduced-calorie diet and increased physical activity, and individual results vary.¹

If anything in your pen, leaflet or prescriber's advice differs from a general guide, follow the pen leaflet and your prescriber. If you notice a new symptom that worries you, tell your prescriber, and you can report suspected side effects through the Yellow Card scheme.¹⁹

For readers comparing GLP-1 medicines generally, our Glp 1 instructions page covers how the class is usually injected.

04 · Weekly routine and timing

Weekly routine: day, time and food

The routine is deliberately simple. Mounjaro is injected under the skin (subcutaneously) once a week, on the same day each week, at any time of day, with or without food.¹ There is nothing to time around meals, no fasting requirement and no need to inject at a particular hour. That flexibility is why most people find the weekly rhythm easier than a daily medicine.

A frequent question is whether to inject in the morning or at night. There is no "best" time of day — Mounjaro works the same morning or evening, with or without food. What matters is the same day each week.¹ Pick a day and time you will remember, and stick to it. Many people choose a weekend morning so early side effects fall on days off, but if your weekends are unpredictable, a fixed weekday evening may suit you better.

Habit does most of the work here. Link the injection to something you already do weekly: a particular television programme, the day the bins go out, or the end of a Sunday shop. Set a repeating phone reminder. The free GLPTrackr companion app, available on iOS and Android, can also help you log doses and keep track of your journey.

Preparing for the injection

Before your day arrives, check that you have a pen with the correct strength for your current step, a fresh needle, and your sharps bin nearby. Look at the label to confirm the strength matches what your prescriber told you. If the label and your instructions do not match, pause and contact the pharmacy rather than guessing.

Take the pen from the fridge, as your leaflet directs, and follow the preparation steps printed in the pen's own instructions.¹³

Changing your injection day

Life shifts, and the licence allows for it. You can change your weekly injection day if needed, as long as at least 3 days (72 hours) have passed since your last dose.¹ In practice that means you can move to a later day without difficulty, but you should not pull the next injection forward so that two doses land close together. Once you have moved, keep the new day each week.

What the weekly cycle looks like over a pen

Each KwikPen contains four weekly doses.¹ That means a pen covers roughly a month of Mondays, or whichever day you choose. When the pen is finished you move on to your next pen, which may be the same strength or a higher one, depending on the plan agreed with your prescriber. Repeat orders re-check suitability, and there is no auto-shipping, so you stay in control of when the next pen arrives.

If you want the dosing side of the story in more depth, our Mounjaro dosage instructions page covers how the steps are paced. Keep your routine steady, keep the day consistent, and the injection becomes a few quiet minutes in your week rather than an event.

05 · Injection sites and rotation

Where to inject Mounjaro and how to rotate

There are three licensed injection areas. Licensed injection sites are the stomach area (at least 5cm from the belly button), the front of the thigh, or the back of the upper arm if someone else gives the injection.¹ That is the whole list. If you are injecting yourself, the stomach and thigh are the practical choices, because you cannot comfortably reach or see the back of your own upper arm.

Rotation matters too. Rotate the site with each dose.¹ Moving the exact spot each week, even within the same area, keeps the skin healthier and the routine comfortable.

A simple rotation plan

Rather than trying to remember where you last injected, build a pattern. One approach is to move between the left and right side of your stomach on alternating weeks, then include a thigh now and then. Another is to note the site in your phone or in GLPTrackr after each dose. Whichever you choose, the pattern should be easy enough that you follow it without thinking.

Keep a sensible distance from your previous spot. If a patch of skin is still tender, bruised or marked from a recent injection, choose a different area that week. Skin that looks healthy and feels normal is the right target.

The stomach area

The stomach is the most popular site because it is easy to see and reach. The licensed instruction is to stay at least 5cm from the belly button, which means choosing a spot clearly to the side or below rather than right next to it. Follow the pen's own instructions for how to place and use the device.

The front of the thigh

The front of the thigh suits people who prefer to sit down for their injection and want a flat, visible surface. Use the front, not the inner or back of the leg, and alternate between left and right thighs across weeks.

The back of the upper arm

The upper arm is licensed only when someone else gives the injection. If you are on your own, do not try to inject the back of your arm. A partner, friend or relative can help, as long as they have read the pen's instructions and handle the needle safely.

Sharps and needle safety

Needles and a sharps bin are included with every order, and the leaflet explains safe disposal.¹³ Never leave a used needle loose or put it in household bins. Keep the sharps bin out of reach of children and pets, and ask your pharmacy or local council how full bins are collected in your area.

For a dedicated look at positioning, see our page on Mounjaro injection locations. If you have any doubts about technique, ask your prescriber during your monthly review rather than experimenting. Comfortable, rotated injections are the goal, and the licensed sites give you plenty of room to achieve it.

06 · The pen dial and clicks

The KwikPen dial: why you never count clicks

People often ask how many clicks are in a Mounjaro pen, or how many clicks give a particular dose. The licensed answer is that clicks are the wrong measure. Any guide that tells you a click count for a strength is not following the product information.

What the window tells you

The window is your confirmation. Before you inject, look at it and check that the number shown matches the strength printed on your pen and the dose your prescriber has set. If it matches, proceed using the pen's own instructions. If it does not, stop and re-read the leaflet.¹³

Why a pen can only deliver what is inside

This is a built-in safeguard. It stops you dialling a dose larger than the remaining medicine, and it is why the last dose in a pen behaves differently from the first.

In other words, if the dial stops short, the pen is finished for dosing purposes. Do not top up from another pen, and do not inject a partial amount. Contact the pharmacy if you think a pen has not delivered the doses it should.

What does a pen look like after four doses?

After the fourth weekly dose the pen is used up. You will not be able to dial a full dose, and the leaflet explains what to do with the finished pen and needle. Rather than judging by sight or by a click count, rely on the window and the stop in the dial. A pen that will not dial to a full dose is simply empty for your purposes.

Can you take a smaller amount from a bigger pen?

Readers sometimes ask how to get a lower dose, such as 2.5mg, from a higher-strength pen, or 5mg from a 7.5mg pen. The answer is that you do not. Each KwikPen comes in a set strength, and the pen is not designed to be used as a variable measuring device.

Altering doses outside the licence means unknown dosing accuracy and no safety data. If you feel a dose is too strong, tell your prescriber, who can adjust the plan safely.

Our Mounjaro injection pen instructions page goes further into the device itself. Whatever the strength, the principle never changes: trust the number in the window, follow the leaflet, and never improvise with the dial.

07 · Missed doses and timing

What to do if you miss a Mounjaro dose

A missed dose is common and has a clear rule. If you miss 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 The key phrase is carry on with your usual day. You do not shift your whole schedule because of one late injection.

The rule has a second half. If more than 4 days have passed, skip the missed dose entirely and take the next one on your normal day — never take two doses within 3 days of each other.¹ This protects you from stacking doses too close together, which is the main safety concern when a schedule slips.

Working through the decision

When you realise you have missed an injection, work out how long ago the scheduled time was. If you are still inside the licensed window, inject as soon as you can, and then return to your normal day the following week. If you are outside it, leave that dose and wait for your normal day. In both cases, never double up to make up for lost time.

The same logic applies if a delivery is delayed or you are away from home. Contact the pharmacy or your prescriber if you are unsure how long it has been or whether the window applies, rather than guessing.

Moving your day on purpose

If a missed dose reveals that your chosen day no longer suits you, you can change it deliberately. You can change your weekly injection day if needed, as long as at least 3 days (72 hours) have passed since your last dose.¹ Pick a new day that fits your week and keep it.

Why consistency matters

A fixed day and an automatic reminder are the simplest fixes.

If you stop altogether

If you decide to stop treatment, after a final dose it takes roughly four to five weeks to clear the system. There is no way to speed this up, and nothing needs doing while it clears.¹ Discuss any plan to stop with your prescriber first so they can talk through what to expect. Mounjaro manages weight; it does not cure the biology behind it. In SURMOUNT-4, people who stopped tirzepatide after 36 weeks regained on average 14% of body weight over the following year, while those who continued treatment lost a further 5.5% on average. Stopping should always be planned with your prescriber, with diet and activity habits ready to carry the load.

Talking to your prescriber

Repeated missed doses are worth mentioning. Your prescriber is there to adjust the plan within the licence, and our monthly reviews exist for exactly this kind of practical issue. If you often forget, a different injection day or a reminder system may be better than pushing through. Our Mounjaro dosage instructions page explains how doses are paced when a plan needs to be adjusted.

08 · Storage and travel

Storing and travelling with your pen

Storage is the other half of using Mounjaro well. Keep Mounjaro pens in a fridge at 2–8°C and never freeze them.¹ That applies to pens you have not yet started, which keep until the expiry date printed on the box.

Once a pen is in use

Once in use, a pen can be kept out of the fridge not above 30°C for up to 30 days — useful for short trips — after which it should be discarded.¹ Keep the pen cap on to protect it from light, and never use a pen that has been frozen.¹ A pen near the back of the fridge or against an ice compartment can freeze, so keep it on a shelf away from the coldest surfaces.

A pen that is nearly finished at the end of its in-use window should be discarded rather than stretched. Sterility and potency are no longer assured outside the tested window. For a fuller walk through, see our Mounjaro storage instructions.

Unopened pens that have been out of the fridge

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 — figures circulating online often come from other countries' labels.¹ Your patient information leaflet and the pharmacy are the right sources, and we are happy to look at the circumstances with you.¹³

Flying with Mounjaro

You can fly with Mounjaro. Carry pens in hand luggage (hold luggage can fall below freezing), ideally in a cool bag with the prescription label or a copy of your prescription.¹ Check destination rules for travelling with prescription injectables before you fly, as they differ between countries.

In-use pens tolerate up to 30 days not above 30°C, so most holidays need no special arrangements; for hot climates use an insulated pouch.¹ Plan your injection day around the trip, and if you will cross time zones, try to inject at a similar local time on your usual day. A small cool bag is a sensible, low-cost accessory if you travel often.

Deliveries

Your order arrives by free next-day tracked delivery in temperature-controlled, discreet packaging, with same-day dispatch when ordered by 3pm. Saturday delivery is £14.99. When your parcel arrives, put pens you are not about to use straight into the fridge, as the leaflet advises.¹³

Everyday storage habits

Keep pens in their carton in the fridge so the label and expiry date stay visible and the pen stays protected from light. Keep them out of sight and reach of children. Write the date you started a pen on the carton or log it in GLPTrackr, so the in-use window never relies on memory. If you are ever unsure whether a pen has been stored correctly, do not inject; contact the pharmacy first.

09 · Dose ladder and pens

The dose ladder: which pen you inject and when

The injection technique stays the same at every strength, but the pen you hold changes as you move up the ladder. Mounjaro is the brand name for tirzepatide, a once-weekly injectable prescription medicine made by Eli Lilly, and it comes as a pre-filled multi-dose pen (KwikPen) in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹

Where everyone starts

Everyone starts Mounjaro on 2.5mg once a week. This starting dose is about letting your body adjust, not about weight loss itself.¹ Treat the early weeks as a rehearsal for the routine: learning the dial, choosing your sites and settling on your day.

How the steps work

After at least 4 weeks the dose increases to 5mg, and can then step up by 2.5mg at a minimum of 4-week intervals (7.5mg, 10mg, 12.5mg) up to a maximum of 15mg weekly, depending on how you respond and tolerate it.¹ The minimum is a floor, not a target.

Many people settle at a maintenance dose of 5mg, 10mg or 15mg — higher is not automatically better, and your prescriber will guide the right pace.¹

Is 7.5mg stronger than 5mg?

Yes, 7.5mg is a higher dose than 5mg and sits one step above it on the ladder. Higher is not automatically better, and your prescriber will guide the right pace. Your prescriber will decide whether to step up, hold or step back within the licence.

What changes when you change pen

When you move to a new strength, the injection steps do not change. What changes is the number you should see in the window. Check it carefully on the first day of every new pen, and read the leaflet again if anything looks unfamiliar.¹³ Our dedicated pages on the Mounjaro 2.5 mg pen instructions and Mounjaro 5mg pen instructions cover those two common starting pens.

How it works, briefly

Tirzepatide is the first treatment of its kind to activate two natural gut-hormone receptors at once: GIP and GLP-1. Together these help regulate appetite, slow how quickly the stomach empties, and improve the way the body responds to insulin.¹ In practice, most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet.

Cost planning

Each dose has its own monthly price, and moving up the ladder changes the cost. For example, the standard 5mg pen is £189.99 per month and the 10mg pen is £274.99. 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). Prices were checked 25 October 2026.

10 · First weeks and results

The first weeks: what is normal after injecting

The early weeks are about adjustment, and experiences differ widely. Some people notice appetite change and early loss in week one, others feel little until a higher dose — both are normal.¹ Early loss includes water weight, so the trend over weeks matters more than any single weigh-in.

How long does Mounjaro take to kick in?

There is no single moment when it switches on. Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle.¹

Realistic pace

Weight loss on Mounjaro is gradual by design. The first weeks on 2.5mg are an adjustment phase and losses are usually modest; most measurable progress builds from 5mg onward, month by month.¹ Trials measured results at 72 weeks — think in months, not days, and judge progress by trend, not individual weigh-ins.

Treatment response 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, your prescriber will discuss whether continuing or stopping is right for you.¹

What the main trial found

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, not instead of them.² Trial averages do not predict your own result.

Side effects and support

If side effects feel stronger than expected, tell your prescriber rather than changing the dose yourself. Our team supports you through monthly reviews, dose-titration and follow-up assessments, and you can reach support by email, portal chat or phone during weekday office hours. You can also report suspected side effects via Yellow Card.¹⁹

The practical advice is to keep the routine boring: same day, rotated sites, correct number in the window, and patience. Our Mounjaro application page explains what happens when you apply for treatment.

11 · 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

12 · NHS, private and ordering

NHS or private: how you get a pen to inject

Instructions are only useful once you have a pen. Mounjaro is available on the NHS, but access is being phased in over several years. NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition, and the NHS primary-care rollout began in June 2025 with the highest-need groups first (initially BMI 40+ with four or more qualifying conditions).⁴⁶ Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment rather than waiting.

Private route with EverydayMeds

EverydayMeds is a GPhC-registered UK online pharmacy (registration 9012878) supplying genuine KwikPens through official LillyDirect supply, direct from Eli Lilly's UK distribution. All six strengths are in stock.

The journey has four steps:

• A free online consultation, a short health questionnaire with no charge and no obligation.
• Review by a GPhC-registered prescriber, not a scoring script. Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full.
• Dispensing by our registered pharmacy, with same-day dispatch when ordered by 3pm.
• Free next-day tracked delivery in temperature-controlled, discreet packaging.

The consultation is free, and the price shown is the price paid, with no hidden fees. Payment options include Visa, Mastercard, Klarna and pay-monthly plans, with no subscriptions. Browse the Mounjaro pen page for live strength-by-strength prices.

What it costs over time

If you step up after 4 weeks on each dose, your first four pens (2.5mg to 10mg) cost £879.96 at standard prices. A first year costs £2,399.88 if you stay on 5mg after your 2.5mg starting pen, up to £3,279.88 if you step up through every dose to 15mg. These are before discounts: a new customer's first order is £40 less with code FIRST40, and every later order is £25 less (code DOSE25). Across the UK pharmacies we track, Mounjaro pens ranged from £143.96 to £319.99 per month as of 25 October 2026.

Aftercare

Ongoing monthly reviews, dose-titration and follow-up assessments by the prescribing team are included, along with side-effect support. Repeat orders re-check suitability, and nothing ships automatically. Needles, a sharps bin and injection guidance are included with every order.

Spotting unsafe supply

Be cautious of any seller offering to supply without a consultation or prescription, or promising specific results. Mounjaro is a prescription-only medicine, and counterfeit alerts are published by the MHRA.⁷ Check any pharmacy on the GPhC register.¹²

Mounjaro (tirzepatide) is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. It is used alongside a reduced-calorie diet and increased physical activity. Individual results vary. This page is information, not a substitute for medical advice.