How Many Doses Does Each Mounjaro Pen Contain?

Why does each pen give you exactly four doses?

Mounjaro is injected once a week, so a four-dose pen maps directly onto a four-week cycle, and if you want to understand exactly how many Mounjaro injections you have per month, that one-injection-per-week rhythm is the key to it. Eli Lilly designed the KwikPen this way deliberately: you start a new pen at the beginning of each month rather than tracking individual cartridge levels or counting remaining units from a vial. It keeps things simple and reduces the chance of dosing errors.

Each dose is pre-set inside the pen. You cannot adjust the amount delivered per injection, and the pen is not refillable. Once all four doses have been used, the pen is spent. If you are ever unsure how much remains in a pen you have already started, our page on checking what's left in a Mounjaro pen walks through the practical signs to look for.

Storage matters across that four-week window. The pen should be kept refrigerated between 2°C and 8°C. For the exact room-temperature window and what to do if the pen has been out of the fridge, the Mounjaro Summary of Product Characteristics on the electronic Medicines Compendium (eMC) is the definitive reference, follow that rather than anything you read on a forum.

How does the four-doses-per-pen fact affect what you pay each month?

Because one pen equals one month, private providers price Mounjaro per pen. The dose strength affects the price: a 2.5 mg starter pen costs considerably less than a 15 mg maintenance pen. That pricing gap widened significantly from September 2025 when Eli Lilly raised UK list prices, the highest dose moved from around £122 to around £330 per pen at list price, with typical private prices across the market now reported in a range of roughly £149 to £375 per month depending on dose and provider. Those figures are widely reported and worth knowing, though actual prices vary.

What those headline figures sometimes omit is everything around the medicine itself. A legitimate prescription-only medicine requires a prescriber to assess you before you receive it. Some providers charge separately for consultation, prescription, delivery and follow-up support. Our breakdown of Mounjaro costs by dose looks at the full picture across the titration schedule, which is worth reading before you compare any two quotes side by side.

If you want to understand why the list price jumped when it did, this page on why Mounjaro's price increased covers the background in detail.

Is the price genuinely all-inclusive, or are there extras to watch for?

This is a question a lot of people have, and rightly so. The honest answer is that it depends entirely on the provider. Some clinics list a low per-pen price and add consultation fees, prescription charges, delivery costs and aftercare as separate line items. That can be fine if each element is clearly disclosed upfront; it becomes a problem when the total only becomes visible at checkout.

At nume, one price covers your consultation, the prescription, the treatment itself, next-working-day delivery and seven-day aftercare. There are no add-ons and no subscription that auto-renews when you're not expecting it, for example, if you order in December and don't want another pen arriving over the Christmas break, you simply don't place a repeat order. Every repeat is clinically re-reviewed first. We are not the cheapest option on the market, and that's a deliberate choice: our infrastructure (identity verification, live weight checks on video, Summary Care Record access, same-day prescriber review) costs money to run properly.

For a full picture of what private treatment typically costs across the titration journey, our Mounjaro price page is the clearest starting point. You can also explore how many pens you'll use per month if you're planning ahead, the answer is almost always one, but there are edge cases worth knowing about.

Should 'cheapest per pen' be the deciding factor?

For an everyday purchase, price is a perfectly sensible filter. For a prescription medicine supplied via an online pharmacy, it's the wrong question to lead with. The MHRA has seized around 20 million doses of illegally traded weight-loss medicines (roughly £45 million worth) including fake pens that have contained insulin rather than tirzepatide. Some of those pens were found circulating in the UK after being advertised at prices well below the legitimate market. A low price from an unverified seller is a warning sign, not a bargain.

The right filter is legitimacy. Any online pharmacy dispensing Mounjaro must be registered with the General Pharmaceutical Council. You can verify a pharmacy's registration directly at the GPhC register, nume's premises registration number is 9012878. Treatment must also follow a genuine clinical assessment: a prescriber reviewing your health, not a checkbox form that approves everyone automatically.

If you're wondering whether prices might come down over time, this page on the future of Mounjaro pricing looks at what the evidence suggests. And if you're ready to take the next step, starting a free consultation with our prescribers is the practical place to begin.