Mounjaro Pen Tutorial: How to Use Your KwikPen (October 2026)

01 · The short version

Mounjaro pen tutorial: the short version

Mounjaro (tirzepatide) is a once-weekly injectable prescription medicine made by Eli Lilly. It comes as a pre-filled multi-dose pen (KwikPen) in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹ You do not draw anything up or mix anything. You dial a dose, place the pen on the skin and inject, following the device instructions in the leaflet that comes with your pen.¹³

02 · Next steps

Getting a prescription

If you are still deciding, you can read how the process works on our Mounjaro KwikPen prescription guide. Mounjaro is a prescription-only medicine, supplied after an online consultation reviewed by a GPhC-registered prescriber.

When you are ready, the Mounjaro pen starts at a standard £169.99 per month for the 2.5mg starting pen, with new customers saving £40 on their first order with code FIRST40. Needles, a sharps bin and injection guidance come with every order. Our wider weight loss clinic page covers the full programme.

Prefer to watch rather than read? Our Mounjaro tutorial video page shows the same routine on screen.

03 · Dialling the dose

Dialling the dose and the question of clicks

Each KwikPen contains four weekly doses.

Before every injection, look at the number in the window and check it matches the strength your prescriber has told you to take that week. If you are unsure, stop and contact the pharmacy rather than guessing. Our Mounjaro pen dimensions page describes the physical pen, useful if you want to know what to expect before it arrives.

The leaflet in your box carries the full device instructions, including how to prepare the pen. Follow those instructions exactly as printed.¹³

04 · Where to inject

Where to inject: stomach, thigh or arm

Mounjaro is injected under the skin (subcutaneously), not into muscle.¹ 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 answers the common question about injecting in the arm. The back of the upper arm is a licensed site, but only when another person gives the injection, because you cannot safely reach and see it yourself. Most people who inject alone choose the stomach or thigh.

Rotate the site with each dose.¹ A simple habit is to move to a different area or a fresh spot within the same area each week, so the same patch of skin is not used repeatedly. If a spot looks bruised, sore or lumpy, choose another and mention it at your next review.

If you buy through a regulated pharmacy, you also receive injection guidance with your order.

05 · Your weekly routine

Building a weekly routine

There is no best time of day to take Mounjaro. It 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.

Setting a recurring phone reminder helps, as does linking the injection to something else you do weekly. Our free companion app, GLPTrackr (iOS and Android), can help you log each dose and keep track of your journey.

Changing your injection day

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 Tell your prescriber at your next review.

Following the dose ladder

Everyone starts Mounjaro on 2.5mg once a week. This starting dose is about letting your body adjust, not about weight loss itself. 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 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.¹¹

Each strength comes as its own pen, so a new strength means a new pen and a fresh check of the number in the window. Our how to take Mounjaro KwikPen guide goes further into week-by-week use.

06 · Missed doses

What to do if you miss a dose

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

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 Do not double up to make up for a forgotten injection.

If you have missed several doses in a row, or are unsure whether your dose should change after a gap, contact your prescriber before restarting. We support customers through monthly reviews, dose-titration and follow-up assessments with the prescribing team, and repeat orders re-check suitability.

07 · Storage and travel

Storing your pen and travelling

Keep Mounjaro pens in a fridge at 2–8°C and never freeze them.¹ 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 — useful for short trips — and must then be thrown away. Do not use a pen that has been above 30°C. Keep the pen cap on to protect it from light, and never use a pen that has been frozen.¹

Unopened pens should be kept 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 — figures circulating online often come from other countries' labels.¹³

Flying with your pen

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. 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. Check destination rules for travelling with prescription injectables before you fly.¹

08 · First weeks

How you may feel when you first start

The 2.5mg starting 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.

Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle.¹³ Most side effects are digestive, and for most people they ease within days to a few weeks as the body adjusts. If you notice a new symptom that worries you, speak to your prescriber, and you can report suspected side effects through the MHRA Yellow Card scheme.¹⁹

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. Trials measured results at 72 weeks — think in months, not days, and judge progress by trend, not individual weigh-ins.²

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. These are trial averages — individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.²

09 · What to avoid

What to avoid while on Mounjaro

Never share a pen with another person.

Modified or unofficial pens

Only use pens supplied through a regulated pharmacy and prescribed to you. We supply genuine KwikPens through official LillyDirect supply, sourced directly from Eli Lilly. Our modified Mounjaro KwikPen page explains why altered or unofficial pens are a risk. Anyone offering to supply without a consultation or prescription should be treated with suspicion, and suspected counterfeits can be reported through the MHRA.⁷

Food and alcohol

There is no direct interaction between Mounjaro and alcohol, but drinking on a reduced appetite and emptier stomach can hit harder than usual. No food is banned on Mounjaro — including bananas — but smaller, slower meals tend to work better.

10 · Reviews and support

Support when something does not feel right

Using an injectable pen for the first time can feel daunting, and that is normal. Our service includes ongoing monthly reviews, side-effect support and dose-titration by the prescribing team, so you are not left to work things out alone. Support is available Monday to Friday, 9am to 5pm, by email at support@everydaymeds.co.uk, through the account portal chat, or by phone on 0333 207 0413.

The consultation is free and the price shown is the price paid, with no hidden fees. Treatment is reviewed by a GPhC-registered prescriber, and we are registered with the GPhC (9012878).

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.

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