Mounjaro Units and In-Between Doses Explained (October 2026)

01 · The core answer

Is there a unit conversion for an in-between Mounjaro dose?

No, there is not a safe or licensed conversion, because the Mounjaro KwikPen does not work in units. It is a pre-filled multi-dose pen that you set by turning the dose knob until the indicator shows the correct dose in the window.¹¹³

That rules out the popular workaround of dividing a target figure by the pen strength and multiplying by a click count. It may look tidy on a calculator, but it is not a method the manufacturer or any UK regulator supports.

Mounjaro is available in six strengths, and the licensed dose steps are fixed. An in-between figure does not match any of them. If a number you have seen online is not one of the six licensed strengths, it is not a dose you will be prescribed.

Every pen is labelled with its strength, and each pen holds four weekly doses of that strength. That is why the ladder moves pen by pen, not in custom amounts.¹

02 · What to do next

What should you do if your dose doesn't match the ladder?

Check the strength printed on your pen, then talk to the prescriber who reviews your treatment. If the figure came from a forum, a social post or a chart, treat it as unverified until a clinician confirms it applies to you.

If you are weighing up a first prescription, the Mounjaro pen product page shows live availability, and the starter pen's standard price is £169.99. Every dose is in stock. If you are already on treatment and unsure about a dose, our wider weight loss clinic guidance explains how reviews work.

03 · Why units confuse people

Why do people ask about units for Mounjaro?

People ask because many injectable medicines are measured in units or millilitres, and online discussion often mixes the formats together. Mounjaro does not follow that pattern. It is a once-weekly pen, set by dialling the dose in mg.¹

The pen is not a vial and syringe set-up. You do not draw up a quantity and you do not read lines on a barrel. The window shows the dose, and the pen will not let you dial past the medicine left inside.¹³ That built-in safeguard is part of why unit conversions are the wrong tool.

04 · How the KwikPen dial works

How does the KwikPen dial work?

The KwikPen is set by turning 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.¹³

Each pen contains four weekly doses. 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.¹³

That last point answers a common worry. If your pen runs short at the end, you do not top up with a partial amount and you do not stretch it. You stop, and you contact the pharmacy or prescriber about the next pen.

05 · Why click counting is risky

Why is counting clicks not recommended?

Counting clicks is not recommended because the pen is built for you to read the window, not to tally sounds. A miscount can mean an unintended dose, and nothing in the product information supports it.¹³

It is a community habit, not a manufacturer instruction. There is no safety data behind it and no assurance of dosing accuracy.

Another point: a pen strength is not a sliding scale you can subdivide at will. Each pen is made for its labelled dose, taken as a full weekly dose. That is the design the licence rests on.¹

People who ask how many clicks a dose is on a higher-strength pen are asking a question the pen was not built to answer. The answer is to use the pen whose labelled strength matches the dose your prescriber has set.

06 · Microdosing and partial doses

What is the safety position on partial doses?

The safety position is clear: "microdosing", meaning 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

The licensed dose ladder already starts low at 2.5mg for tolerability. If side effects are the concern, your prescriber can hold a dose longer or step down within the licence.¹

Altering doses outside the licence means unknown dosing accuracy and no safety data.

If you feel the next licensed step is too big a jump, that is a useful thing to tell your prescriber. It is a reason to talk, not a reason to improvise.

07 · The licensed dose ladder

How does the licensed dose ladder work?

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, depending on how you respond and tolerate it.¹¹¹

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

Notice what is missing from that ladder: any step between the listed strengths. Each rung is a full labelled pen. If you want to see how the middle rungs read, we have pages on the 7.5mg step and the 12.5mg step. The same logic applies to the generic name, as our page on tirzepatide units at the starting strength shows.

08 · Holding or stepping down

Can you stay on a dose longer or step down?

Yes, within the licence your prescriber can hold a dose for longer or step down if side effects are the concern.¹ That is the licensed answer to wanting a gentler pace, and it means you never need a made-up intermediate figure.

The same idea answers questions such as how long to stay on 5mg. The ladder gives a minimum gap before stepping up, not a required step. Many people settle at 5mg, and your prescriber guides the pace based on how you respond and tolerate treatment.¹

Is 5mg strong? It is the first step above the starting dose and a recognised maintenance dose. Whether it is right for you depends on your response and tolerance, which is why reviews matter.

What about taking a week off? That is a prescriber conversation. If a dose is simply late, take it as soon as you can within 4 days (96 hours) of the scheduled time.

09 · Missed doses, day changes, storage

What are the practical rules for timing and storage?

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 the missed dose entirely and take the next one on your normal day. Never take two doses within 3 days of each other.¹

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

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. Many people choose a weekend morning so early side effects fall on days off.¹

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 pen cap on to protect it from light, and never use a pen that has been frozen.¹¹³

10 · What results to expect

Does the dose affect the results you can expect?

Dose and results are linked, but trial averages do not predict your own result. 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

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. Think in months, not days, and judge progress by trend, not individual weigh-ins.

Not losing weight on 5mg? 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. A made-up intermediate dose is not part of that conversation.

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 and private access

How do you get Mounjaro on the NHS or privately?

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.

Privately, the journey is: a free online consultation, a review by a GPhC-registered prescriber, dispensing by our registered pharmacy, then free next-day tracked delivery in temperature-controlled packaging. Orders placed by 3pm are dispatched the same day. Declined consultations are refunded automatically, and ongoing monthly reviews are included.

Our Mounjaro comes from official LillyDirect supply, so you receive genuine KwikPens in the licensed strengths. New customers save £40 on their first order with code FIRST40, and an automatic £25 reorder discount applies to every future order (code DOSE25). Prices checked 12 October 2026.