Mounjaro KwikPen 2.5 mg: How to Use It, With Video Guidance (October 2026)

01 · Step by step

How to use the Mounjaro KwikPen 2.5mg

The pen is a pre-filled, multi-dose device that delivers one weekly dose at a time. Every pen contains four weekly doses, so one 2.5mg pen covers your first four weeks.¹ The pen's patient information leaflet contains the full illustrated instructions for use, and you should follow those for the mechanical steps.¹³

• Get ready: pick your weekly injection day and have your pen, a new needle and your sharps bin to hand. Needles, a sharps bin and injection guidance come with every order.
• Set the dose: turn the dose knob until the dose indicator shows the correct dose in the window. You confirm the dose by the number in the window, never by counting clicks.¹
• Choose a site: 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. Rotate the site with each dose.¹
• Inject: the injection goes under the skin (subcutaneously). Follow the pen's instructions for how to press and how long to hold.
• Finish: put the used needle in the sharps bin and replace the pen cap, which protects the pen from light.¹

If you prefer to watch rather than read, see our Mounjaro pen video guide. Our written 2.5mg how-to guide covers the same ground in text.

02 · Getting your pen

Getting a 2.5mg pen and what it costs

Mounjaro is prescription-only, so you start with a free online consultation reviewed by a GPhC-registered prescriber. Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full.

The Mounjaro pen at 2.5mg has a standard price of £169.99 for four weeks. New customers save £40 on their first order with code FIRST40, and an automatic £25 reorder discount applies to every future order (code DOSE25). All six doses are in stock, and we dispatch the same day when you order by 3pm, with free next-day tracked delivery in temperature-controlled packaging. For the full price picture, see our 2.5mg price guide.

Ready to begin? Start your free consultation. Our pens come through official LillyDirect supply, direct from Eli Lilly's UK distribution.

03 · Clicks and the dose window

How many clicks are in a Mounjaro pen?

There is no click count to follow. The KwikPen is set by turning the dose knob until the dose indicator shows the correct dose in the window.¹

The pen will not let you dial past the medicine left inside. If the window will not turn to a full dose, the pen does not contain enough for one and should not be used for a partial injection.¹ Contact the pharmacy if that happens.

04 · Timing and missed doses

Best day, time and missed doses

There is no best time of day: Mounjaro works the same in the morning or evening, with or without food. What matters is using the same day each week.¹ Many people choose a weekend morning so early side effects fall on days off.

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. If more than 4 days have passed, skip it and take the next dose on your normal day. Never take two doses within 3 days of each other.¹

You can change your injection day if at least 3 days (72 hours) have passed since your last dose.¹

05 · Storage and travel

Storing and travelling with your pen

Keep pens in a fridge at 2–8°C and never freeze them. 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. Do not use a pen that has been above 30°C or has been frozen.

You can fly with Mounjaro. Carry pens in hand luggage, because hold luggage can fall below freezing, ideally in a cool bag with the prescription label or a copy of your prescription. For hot climates use an insulated pouch.¹

Unopened pens belong in the fridge and keep until the printed expiry date. If an unopened pen has been out of the fridge, check the leaflet and ask the pharmacy rather than relying on a day limit you have seen online, as such figures often come from other countries' labels.¹³

06 · What 2.5mg is for

What to expect at 2.5mg

Everyone starts on 2.5mg once a week, and this dose is about letting your body adjust, not weight loss itself. After at least 4 weeks the dose rises to 5mg, then can step up by 2.5mg at minimum 4-week intervals to a maximum of 15mg, depending on response and tolerance.¹

Experiences differ widely. Some people notice appetite change in week one, others feel little until a higher dose, and both are normal. Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle.¹ Read more in our guide to 2.5mg side effects.

In the SURMOUNT-1 trial of 2,539 adults, people lost on average 15% of body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, versus 3.1% with lifestyle changes alone. Trial averages do not predict your own result, and treatment works alongside a reduced-calorie diet and more physical activity.² Think in months, not days.

07 · 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