# Mounjaro: a five-day half-life, six dose steps and your shot day > Mounjaro (tirzepatide) half-life is about 5 days per the label. Track your weekly shot, 2.5 mg step-ups, the 4-day missed-dose window and sites in Peppy. Source: https://peppytracker.com/compounds/tirzepatide-mounjaro/ Last updated: 2026-08-30 Mounjaro is Eli Lilly's once-weekly tirzepatide pen approved for type 2 diabetes, a dual GIP/GLP-1 receptor agonist with strong effects on glycemic control and body weight. The Peppy catalog lists it as a pen dosed in mg, weekly, with a half-life of about 120 hours. Peppy keeps the shot day, advances the 2.5 mg step-ups and charts what is still active. ## Tracking Mounjaro: what matters The Mounjaro half life is about 5 days per the label, a little shorter than semaglutide's week. That shows up in the rules you live with: a 4-day window for a missed shot instead of 5, a 72-hour minimum between shots if you move your day, and an "active in your system" curve that dips more noticeably before the next shot. Peppy draws that curve from the catalog's 120-hour figure as an estimate; the calendar and the Today countdown are the parts you use every week. Mounjaro's ladder is the longest in the GLP-1 catalog: 2.5, 5, 7.5, 10, 12.5 and 15 mg, each held at least 4 weeks on the label. Dose step-ups (Pro) put your prescriber's version on the calendar, so the dose on the card, the reminder and the Log shot sheet is always the one for this week. If a step is held longer, you edit one duration. The [titration tracker guide](https://peppytracker.com/guides/glp-1-titration-schedule-tracker/) shows the setup. Pens are the inventory unit. Single-dose pens are one dose each; if you use a multi-dose pen or vial, enter its dose count. Inventory (Pro) turns that into "~ 3 doses left, runs out around Oct 3" and a refill reminder. Nausea and constipation often shift with each step, so the daily check-in, with weight pulled from Apple Health, is what makes the Progress chart (Pro insights) worth looking at before an appointment. ## Schedule and cycles The Peppy catalog lists Mounjaro as weekly with a dose ladder of 2.5, 5, 7.5, 10, 12.5 and 15 mg (catalog listing, not a recommendation). The label describes one shot a week on a consistent day, any time, with or without meals, with the 4-day missed-dose window and the 72-hour rule for changing days. Peppy computes missed and overdue from the schedule rather than storing them, so a late shot appears once, on the day you took it, and the [weekly reminder](https://peppytracker.com/guides/weekly-injection-reminder/) resets from there. There is no cycling on the label; use Pause if your prescriber stops you for a while. ## How to do this in Peppy 1. Open **Protocols**, tap **+**, search "Mounjaro". Pen, mg, weekly and the half-life come from the catalog. 2. Enter the current dose, weekday and time. 3. Add the rungs under **Dose step-ups** (Pro), 4 weeks each unless told otherwise. 4. Enter pens and doses per pen in **Inventory** (Pro). 5. On shot day, tap the countdown on **Today** or the Next Shot widget (Pro), pick the suggested site on the body map and log. 6. Do the **check-in** daily and review **Progress** for step-up markers on the weight trend. The [Mounjaro tracker page](https://peppytracker.com/trackers/mounjaro-tracker/) covers the full weekly routine; [Zepbound](https://peppytracker.com/compounds/tirzepatide-zepbound/) is the same molecule under its weight-management label. ## Frequently asked ### What is the Mounjaro half life? The Mounjaro label reports an elimination half-life of approximately 5 days, which is what enables once-weekly dosing. The Peppy catalog lists 120 hours and uses it for the "active in your system" chart, an estimate rather than a measurement. ### What if I miss a Mounjaro shot? The label says to take a missed dose as soon as possible within 4 days (96 hours), and if more than 4 days have passed, to skip it and take the next dose on the regular day. Peppy shows the missed shot and the next due date; the decision is your prescriber's. See the [missed dose guide](https://peppytracker.com/guides/missed-glp-1-dose/). ### How does the Mounjaro dose step-up work? The label starts at 2.5 mg weekly for 4 weeks, then 5 mg, with further 2.5 mg increases after at least 4 weeks on the current dose, up to 15 mg. Peppy's dose step-ups (Pro) model that ladder and advance the dose on the card and reminder. Your prescriber sets the actual steps. ### Can I change my Mounjaro shot day? The label allows the weekday to change as long as the two doses are at least 3 days (72 hours) apart. In Peppy, edit the weekday on the protocol; future shots move, past logs stay put. ### Where do you inject Mounjaro? The label lists abdomen, thigh or upper arm, rotating sites. Peppy's body map suggests the next site and shows when each was last used. See the [rotation guide](https://peppytracker.com/guides/injection-site-rotation/). ### How long does Mounjaro stay in your system? The Peppy catalog lists a half-life of about 5 days for Mounjaro. After roughly five half-lives, about 3.6 weeks, most of a single dose has cleared. That is an estimate from the half-life, not a measurement, and individual clearance varies. ### Can I track Mounjaro in Peppy? Yes. Mounjaro is one of 123 compounds built into Peppy, with its form, unit and typical frequency prefilled. Add it as a protocol, set your schedule, and Peppy handles the countdown, the log and the reminders (Pro). ### Where should I inject Mounjaro? Follow your prescriber's instructions. For subcutaneous shots the GLP-1 labels list the abdomen, thigh and upper arm and say to rotate. Peppy's body map has 13 sites, suggests the next one, and shows when each was last used. Read the [site rotation guide](https://peppytracker.com/guides/injection-site-rotation/). --- Peppy is a tracking tool, not medical advice. Dose calculations are mathematical conversions only. Always follow your prescriber's instructions and verify every draw-up yourself. Peppy is a free iPhone app (Pro subscription optional). App Store: https://apps.apple.com/us/app/peptide-tracker-peppy/id6775005514