The 15 mg Mounjaro Pen: What It Is and How to Track Your Dose

Mounjaro (tirzepatide) is a once-weekly injectable medicine that acts on both GLP-1 and GIP receptors. It is supplied in a range of pre-filled pen strengths, and treatment typically begins at a low starting dose before being adjusted upward over time. The 15 mg pen sits at the top of that range.

The available dose strengths

According to the electronic Medicines Compendium (eMC), Mounjaro is available in the following strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg — each supplied as a separate, single-use pre-filled pen. You can read more about how the different strengths fit together on the Mounjaro pen dose overview page.

Each pen delivers a fixed dose

A common question is whether it is possible to extract a lower dose from a higher-strength pen — for example, drawing 5 mg from a 7.5 mg pen. Each Mounjaro pen is a single-use, pre-filled device designed to deliver one fixed, pre-set dose. It is not possible to reliably dose 5 mg from a 7.5 mg pen; doing so would involve manipulating the device in a way it is not designed for, and would not give an accurate or safe dose. If you are on a 5 mg dose, a dedicated 5 mg pen is the appropriate device.

Titration is prescriber-led

Moving from one strength to the next — including reaching the 15 mg pen — is a decision made by your prescriber based on your response and tolerability. Some people stay at a lower maintenance dose; others progress to higher strengths. Neither path is better in the abstract; what matters is what your prescriber determines is right for you. If you have questions about where you are in your titration, that conversation belongs with your prescribing clinician.

For context on neighbouring dose stages, see the pages on the 7.5 mg Mounjaro dose and the 12.5 mg Mounjaro dose, which sit just below 15 mg in the titration schedule.

Any side effects you notice — which are commonly reported during dose increases — should be logged and discussed with your prescriber or doctor. If anything feels severe or persistent, contact your healthcare professional promptly rather than waiting for your next appointment.

Staying consistent with a once-weekly injection schedule matters — and at any dose stage, keeping a clear record of when each pen was used is genuinely useful, both for your own peace of mind and for discussions with your prescriber.

GLP Trackr's dose logging feature lets you record each injection as you go: the dose strength, the date, and the time. At 15 mg — the top of the titration ladder — having an accurate log means you always know exactly when your last dose was given, which is especially helpful if your schedule shifts around travel or other commitments.

Beyond dose logging, the app's side-effect tracker lets you note anything you experience after an injection and spot patterns over time. That kind of record is exactly what your prescriber needs to make informed decisions about your ongoing treatment — the app even generates a doctor report you can bring to an appointment.

You can explore the full picture of managing your Mounjaro treatment on the Mounjaro dosing hub.

GLP Trackr is available free on the App Store and Google Play, with a 7-day free trial. Log your dose the moment you inject, and build a record that actually supports your journey — download it free and start your trial today.

GLP Trackr is an informational tracking tool. It does not provide medical or dosing advice. All decisions about your dose — including whether to continue, adjust, or pause — should be made with your prescriber or doctor, who knows your full medical history.