How Many 5mg Doses in a 15mg Mounjaro Pen? (October 2026)

01 · The answer

How many 5mg doses are in a 15mg Mounjaro pen?

There are none in licensed use. Mounjaro comes as a pre-filled multi-dose KwikPen in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹ Every pen contains four weekly doses, and each dose is the strength named on the pen.¹³ A 15mg pen therefore gives four injections of 15mg across four weeks.

The same logic applies at every strength. The same logic applies to the 10mg pen and the 2.5mg pen: each holds four doses of its own strength.

The pen is built and licensed to deliver four doses of its labelled strength. Using it any other way is outside the licence, and the pen's design does not support it.¹³

02 · What to do

What to do if you need a 5mg dose

If your prescriber has you on 5mg, you need the 5mg pen. It holds four weekly 5mg doses, so one pen covers four weeks. You can see the current Mounjaro pen prices and options on the product page. The 5mg pen costs £189.99 per month at the standard price, which works out at £47.50 per week. All six doses are in stock.

An automatic £25 reorder discount applies to every future order (code DOSE25). The price shown is the price paid, and the consultation is free.

Many people who find a pen strength awkward are really asking about their dose plan. If you have a higher-strength pen left over and your prescriber wants you on a lower dose, do not try to make the pen do something it was not designed for. Contact the prescriber who issued it. Within the licence, a prescriber can hold you at a dose for longer or step you down.¹

03 · Ordering

How ordering the right pen works

Mounjaro is prescription-only, so every order starts with a consultation. There are four steps:

• Free online consultation. A short health questionnaire with no charge and no obligation.
• Prescriber review. A GPhC-registered prescriber reviews your answers. 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 and dispatch. Our registered pharmacy dispenses your pen. Orders placed by 3pm are dispatched the same day.
• Delivery. Free next-day tracked delivery in discreet, temperature-controlled packaging. Saturday delivery is £14.99.

Needles, a sharps bin and injection guidance come with every order. Repeat orders re-check your suitability, and we never auto-ship. Ready to begin? Start your free consultation. Our supply comes through official LillyDirect channels, directly from Eli Lilly's UK distribution, so you receive genuine KwikPens.

For the cost over a longer horizon, the first four pens (2.5mg, 5mg, 7.5mg and 10mg pens, four pens in total) cost £879.96 at standard prices. A first year of 13 pens costs £2,399.88 if you settle at 5mg, up to £3,279.88 at 15mg. A new customer's first order is £40 less, and every later order is £25 less. For the starting price in detail, see our Mounjaro starter pen price guide.

04 · Why a pen holds four doses

Why every Mounjaro pen holds four doses

Every Mounjaro KwikPen is a pre-filled pen containing four weekly doses, and the strength on the label is the dose each injection delivers.¹³ That design is why one pen lasts four weeks on a once-weekly schedule. It is also why the question "how many 5mg doses are in a 15mg pen?" has a plain answer: the pen was never intended to deliver 5mg.

It helps to think of the pen as a fixed-purpose device. A 2.5mg pen is for the starting dose. A 5mg pen is for the first step up. Each strength is calibrated for its own dose, and you do not choose a pen by the volume of medicine it contains. You choose it by the dose your prescriber has set.

Where does the confusion come from? People may assume one big pen should supply many small doses, like a larger bottle of liquid medicine. A KwikPen is not a measuring jug. It is a dose-setting device, and the licensed use is one pen, four doses, one strength.

That rule is a safeguard. It stops you using up the last of a pen to make a short or uneven dose.

There is a practical side too. Your dose is chosen by a prescriber who looks at your health, how you tolerate the medicine and your response. That judgement is built into the licensed ladder of strengths. When your prescriber moves you to a different dose, you move to a different pen. You do not adapt the pen you already have.

If you are not sure which pen you have, read the strength printed on the label and on the box. If it does not match the dose your prescriber told you to take, stop and ask. Our prescribing team can help current customers on the support line, Monday to Friday, 9am to 5pm. You can also read about how the dial works in our guide on how many turns a Mounjaro pen takes.

In short: one pen, four weekly doses, one strength. Treat the strength on the label as the dose, and do not try to turn a high-strength pen into a source of lower doses.

05 · Clicks and the dose window

Clicks, the dial and the dose window

You turn the dose knob until the dose indicator shows the correct dose in the window. Follow the pen's instructions for the injection itself.

Why not count clicks? The audible click is a mechanical feedback feature, and it is not a measurement you can rely on. Counting leaves you open to losing count and misjudging a dose, with no way to check the result. The number in the window is the one thing the pen and its patient leaflet tell you to rely on. If you want a deeper explanation, see our pages on 15mg pen clicks and the 15mg click question.

Common click questions answered plainly:

• How many clicks does a Mounjaro pen make? Do not count them. Use the number in the window.
• How many clicks for 5mg from a 7.5mg pen? A 7.5mg pen is not designed to give 5mg. You need the 5mg pen.
• How many clicks is 4mg on a 5mg pen? 4mg is not a strength on the licensed ladder. Speak to your prescriber.
• How many clicks are in a 12.5mg pen? It holds four 12.5mg doses. Again, rely on the window.

Notice the pattern. Each question tries to turn a pen into something it is not. The answer is the same each time: use the pen prescribed for your dose.

If you are worried that a pen is not dialling correctly, or the window will not show a full dose, do not force it. Keep the pen and contact the pharmacy that dispensed it. Dispensed prescription medicines cannot normally be returned, but if an item is faulty, damaged or wrong, contact us within 3 days and we will help.

Finally, never use a pen you suspect has been frozen or damaged. Keep the pen cap on, and do not use a pen that has been above 30°C or frozen.

06 · Why splitting doses is unsafe

Why splitting a pen or microdosing is not safe

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

First, the dose you took would be unverifiable. Second, there is no safety or efficacy evidence for unlicensed regimens. The licensed ladder already starts low for tolerability, with 2.5mg as the first dose.¹

People look at splitting for understandable reasons. Some want to ease side effects. Some find prices hard to manage. Some have a higher-strength pen after being moved up and then down again. Each of these has a safer route:

• Side effects at a dose.
• Cost worries. Talk to your prescriber rather than adjusting the pen yourself. The Mounjaro pen product page shows live prices, and there is a first-order and reorder discount.
• Leftover or wrong-strength pen. Ask your prescriber what to do. Do not use it for a different dose.

Also remember that a prescriber looks at the whole picture: your BMI, medical history and current medicines.¹ Dose decisions made at home skip that assessment.

If a seller, forum or video tells you it is fine to draw doses from a different pen, treat it as unsafe advice. There is no regulator-approved method for it. Our advice is simple: use the pen prescribed for your dose, once a week, and talk to your prescriber about anything that concerns you. If you have a side effect, you can also report it to the MHRA Yellow Card scheme.¹⁹

07 · The dose ladder explained

What are the different doses of Mounjaro?

Mounjaro comes in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg, taken once a week.¹ Everyone starts on 2.5mg. That starting dose is about letting your body adjust, not about weight loss itself. After at least 4 weeks the dose increases to 5mg, and it 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

This ladder explains the original question. Your prescriber moves you through strengths, and each step uses a pen of that strength. A person on 5mg uses a 5mg pen. A person on 15mg uses a 15mg pen. There is no step on the ladder where a 15mg pen delivers 5mg.

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 Some people reach their goal at a lower strength and never need the top dose.

The four-week minimum is a floor, not a target. A prescriber may hold you at a dose for longer.

If you step up after 4 weeks on each dose, your first four pens (2.5mg to 10mg) cost £879.96 at standard prices, before discounts. Your first order is £40 less with code FIRST40, and every later order is £25 less than the standard price. Your own path may be slower or stop earlier, depending on how you respond.

Beyond that, 12.5mg costs £289.99 per pen and 15mg costs £299.99 per pen at standard prices. Switching to us at a high dose from another provider? Your first order of the 15mg pen is £259.99, a first-order price with code FIRST40.

One more point on pen sizes: because each pen has four doses, ordering is simple to plan. One pen per four weeks, at your current dose, with a repeat order before the pen runs out.

08 · Keeping your pen safe

Storage and in-use limits for your pen

Keep Mounjaro pens in a fridge at 2–8°C and never freeze them.¹³ 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. Keep the pen cap on to protect it from light, and never use a pen that has been frozen.

Unopened pens should be kept in the fridge and keep until the expiry date printed on the box.¹³ 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.

Travelling is straightforward. 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. 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, and check destination rules for travelling with prescription injectables before you fly.¹³

Our deliveries arrive in temperature-controlled packaging by free next-day tracked delivery. Put your pen in the fridge as soon as it arrives, unless you are about to use it.

What about the injection routine around the pen? Mounjaro is injected under the skin once a week, on the same day each week, at any time of day, with or without food. Licensed 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. Rotate the site with each dose.¹³

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 and take the next one on your normal day. Never take two doses within 3 days of each other.¹ You can change your injection day, as long as at least 3 days (72 hours) have passed since your last dose.

None of these rules involve using one pen to cover several strengths. The routine is the same at every dose: one pen, four weekly injections, store correctly, discard after the in-use window.

09 · What results to expect

What results look like at each dose

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.

At 72 weeks, 85% of participants on 5mg, 89% on 10mg and 91% on 15mg had lost at least 5% of their body weight. Half of participants on 10mg and 57% on 15mg lost at least 20% of their body weight.² As a worked example only, for someone starting at 100 kg, 20.9% is about 21 kg.

The answer to "which dose do I need?" is not "the biggest pen". The trial figures show benefit at 5mg, and many people settle there.¹ Your dose is a decision about response and tolerability, made with your prescriber. A pen should match that decision.

Results arrive gradually 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, so think in months, not days, and judge progress by trend, not individual weigh-ins.² Experiences in the first weeks differ widely: some people notice appetite change and early loss in week one, others feel little until a higher dose. Both are normal. Early loss includes water weight, and mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle.

Your prescriber reviews your response. 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.² That review depends on knowing exactly what dose you took, and unlicensed splitting would make that impossible. Reliable records help your prescriber advise you well.

Our free companion app, GLPTrackr, lets you track your doses and progress on iOS and Android. Ongoing monthly clinical reviews are part of the service, so you do not have to work out dose changes alone.

10 · Eligibility and NHS access

Who can be prescribed Mounjaro, and NHS access

Mounjaro is licensed for weight management in adults with a BMI of 30 or above, or a BMI between 27 and 30 with at least one weight-related condition such as high blood pressure, high cholesterol, obstructive sleep apnoea, cardiovascular disease, prediabetes or type 2 diabetes.¹ It must be used alongside a reduced-calorie diet and increased physical activity. A prescriber will assess your BMI, medical history and current medicines before deciding whether it is suitable for you.

On the NHS, Mounjaro is available, 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.

Whether you are treated on the NHS or privately, the pens work the same way. A pen holds four weekly doses of the strength on its label, and your clinician decides your dose. The NHS information page for tirzepatide is a good neutral reference.⁵

If you are private, here is what our service involves. The consultation is free, and a GPhC-registered prescriber reviews it. The pharmacy is GPhC-registered (number 9012878), and you can check the register yourself.¹² Aftercare includes ongoing monthly reviews, dose-titration and follow-up assessments, and side-effect support. Payment options include Visa, Mastercard, Klarna and pay-monthly options, with no subscriptions.

The MHRA publishes counterfeit medicine alerts and runs the Yellow Card scheme.⁷ Be wary of anyone offering to supply Mounjaro without a consultation or prescription, or offering unusually cheap pens, vials or "split" doses. Our supply comes directly from Eli Lilly's UK distribution through LillyDirect, so you receive genuine KwikPens in all six strengths.

Not sure which route is right? Compare options on our weight loss treatments page, or begin with the free consultation. Either way, a prescriber chooses your pen, and you take it as prescribed.

This page is information, not a substitute for medical advice. Mounjaro (tirzepatide) is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. Individual results vary.

11 · Side effects and long-term safety

Side effects, long-term questions and who to ask

The commonest early effects of Mounjaro are mild nausea, altered appetite and tiredness in the first days after each injection, and they usually settle.² The most common effects, affecting more than 1 in 10 people, are nausea, diarrhoea, vomiting, constipation and abdominal discomfort. People often ask about long-term side effects too. Your prescriber can go through the full side-effect list in the patient information leaflet with you.

Why does this tie into pen use? Because dose accuracy is part of safety. If you take the licensed dose from the pen prescribed for you, you know what you have taken, and your prescriber can read your side effects against a known dose. If you split a pen or count clicks, you cannot tell whether a side effect came from the medicine, the dose or an error.

Practical points for managing early effects:

• Note which day you inject and how you feel over the following days. A consistent day each week helps.
• Tell your prescriber if effects are troublesome.
• Choose an injection day that suits you. Many people pick a weekend morning so early effects fall on days off, and there is no best time of day.

Tirzepatide has a half-life of about five days, so after a final dose it takes roughly 4–5 weeks to clear the system.¹ There is no way to speed this up, and nothing needs doing while it clears.

Contraception is worth knowing about. The medicine can reduce absorption of oral contraceptives because stomach emptying slows, so discuss this with your prescriber and see the MHRA guidance.⁷ The SmPC advises switching to a non-oral method, or adding a barrier method (such as condoms), for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.¹ If you take insulin or sulfonylureas, doses may need adjusting because of the risk of low blood sugar, so tell your prescriber about all your medicines.

If you notice a new symptom, speak to your prescriber, and report suspected side effects through the Yellow Card scheme.¹⁹ Reports help regulators monitor medicines and take a few minutes to submit. Our support team is available Monday to Friday, 9am to 5pm, by email at support@everydaymeds.co.uk, through the account portal chat or on 0333 207 0413.

12 · 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