How Many Clicks for 5mg Mounjaro From a 12.5 Pen? (October 2026)

01 · The short answer

Can you take 5mg from a 12.5mg pen by counting clicks?

No. The Mounjaro KwikPen is set by turning the dose knob until the indicator shows the correct dose in the window, and you confirm the dose by that number, never by counting clicks.¹³

Each pen contains four weekly doses, and the pen will not let you dial past the medicine left inside.¹³ 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.¹³

02 · Safety

Why a click count is not safe

Taking smaller or more spread-out doses than the pen is designed to deliver 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.¹

03 · Next steps

What to do if you need 5mg

Use a pen of the strength you were prescribed. Mounjaro comes in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹ A 5mg Mounjaro pen costs £218.99 per four-week pen at the standard price, and all six doses are in stock.

If you have been given a higher strength and think you should be on a lower one, speak to your prescriber. They can hold a dose longer or step down within the licence if side effects are the concern.¹ If you are new to us, you can start your free consultation, reviewed by a GPhC-registered prescriber.

04 · How the dose ladder works

How the licensed dose ladder works

Everyone starts Mounjaro on 2.5mg once a week. This starting dose is about letting your body adjust, not about weight loss itself.¹ 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.¹

Many people settle at 5mg, 10mg or 15mg. Higher is not automatically better, and your prescriber guides the right pace.¹¹ Related questions are covered in our guides on 5mg from a 7.5 pen.

05 · Pen doses and the window

How many doses are in a pen and what the window shows

Each KwikPen contains four weekly doses, so one pen covers four weeks.¹³ You inject under the skin once a week, on the same day each week, at any time of day, with or without food. Rotate the site with each dose.¹³

Whatever the strength, you read the dose from the window. Guides such as 5mg from a 15mg pen and 2.5 from a 12.5 pen ask the same question, and the answer is the same: follow the window, not a count.

06 · Priming and pen problems

Priming, a stuck dial and a forgotten cap

The exact priming steps are in the patient information leaflet supplied with your pen. Follow the pen's instructions, and if you forgot a step, such as priming or removing the cap, do not guess and do not give a second injection to compensate.¹³

If the dial will not turn to a full dose, the pen does not contain enough for one and should not be used for a partial injection.¹³ Contact our support team on 0333 207 0413 (Monday to Friday, 9am to 5pm) or your prescriber for advice.

If you have missed a dose, take it as soon as you can within 4 days (96 hours) of the scheduled time. After more than 4 days, skip it and take the next on your normal day, never two doses within 3 days of each other.¹³

07 · If 5mg is not working

Why 5mg may feel like it is not working

Weight loss on Mounjaro is gradual by design. The first weeks on 2.5mg are an adjustment phase, and most measurable progress builds from 5mg onward, month by month.¹¹ In SURMOUNT-1, people lost on average 15% of body weight on 5mg over 72 weeks, versus 3.1% with lifestyle changes alone. Individual results vary.²

For someone starting at 100 kg, 15% is about 15 kg. Judge progress by trend, not single weigh-ins. 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.¹¹ See also how many clicks a 5mg pen has.

08 · Storage of in-use pens

Storing 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 not above 30°C for up to 30 days, after which it should be discarded. Keep the cap on to protect it from light.¹³

You can also read our notes on 2.5mg from a 5mg pen and intermediate doses on a 5mg pen. Mounjaro is prescription-only and supplied after an online consultation reviewed by a GPhC-registered prescriber. This page is information, not a substitute for medical advice. See all weight loss treatments.